Vapor phase thermoset composite recycling to recover carbon fiber

Abstract

Aspects of the disclosure apply a reactive vaporized solution in a reaction chamber to a component including hardened resin encapsulated fiber strands or fiber fabric (e.g. carbon fiber) that is to be recycled wherein cured resin removal occurs using a reactive vaporized chemical solution that is held at one or more specified reaction temperatures, pressures, and times to allow sufficient breakdown and removal of the harden resin to occur without thermal degradation of the hardened resins or its reaction products to yield at least one bare continuous carbon fiber strand or fabric segment that is wound or otherwise stored for subsequent use as a continuous strand or fabric segment which has a strength approaching that of newly formed strands or fabric segments (e.g. within 20% of the original strength). The reactive vaporized solution includes at least one component that provides a catalytic and a swelling function for removing hardened resin.

Description

Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTVAPOR PHASE THERMOSET COMPOSITE RECYCLING TO RECOVER CARBON FIBERCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 752,189, filed January 31, 2025, which is incorporated herein by reference in its entirety.STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT

[0002] This invention was made with Government support under Contract DE-AC0576RL01830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.TECHNICAL FIELD

[0003] The disclosure generally relates to the field of recycling composite materials and more specifically to the field of recycling epoxy-carbon fiber composites, even more specifically to recycling such composites using catalyst containing vapor where the vapor degrades the epoxy without degrading the carbon fibers or attaching degraded epoxy by products to allow carbon fiber recovery.BACKGROUND

[0004] Composite recycling can take three forms: 1) mechanical, 2) thermal, and 3) chemical. Furthermore, composite material waste comes from different sources: (a) dry composites where formation occurs via fibers being placed in a mold or otherwise positioned without pre-impregnated resin with resin being thereafter added during manufacturing; (b) pre-impregnated composites wherein fibers are saturated with resin prior to shaping or manufacturing which may lead to waste formation (and need for recycling) prior to manufacturing due to degradation resulting from prolonged delay in using the pre-impregnated material (i.e., expired waste) or during manufacturing as excessAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTmaterial is removed or trimmed away (i.e., trim waste), or (c) post processing of composites or from used composite components or parts (i.e., cured waste).

[0005] A need exists for improved methods and systems for recycling carbon fibers, glass fibers, and other high-value reinforcing fibers of a similar nature from resin / fiber composite systems.SUMMARY

[0006] It is an object of some aspects of the disclosure to provide an improved method for composite material recycling that provides for recycling of continuous carbon fiber strands (e.g. having lengths >= 25 mm, >= 10 cm, >= 1 m, >= 10 m, or >= 100m. and / or having lengths >=25%. >=50%, >=70%.>=85%, >=90%, >=95%, =100% of lengths of the wrapped strands that were encapsulated, e.g., originally forming part of a component that is being at least partially recycled). In some aspects recycled strands may be on the order of tens of meters to hundreds of meters or even more. In other aspects other types of fibers (e.g. glass fibers) may be recycled from composites having hardened resin encapsulants.

[0007] It is an object of some aspects of the disclosure to provide an improved method for composite material recycling that provides for recycling of large area carbon fiber fabric segments (e.g. > 20 cm2. > 200 cm2. > 200 cm2. > 2000 cm2, > 2 m2, and / or >=25%, >=50%, >=70%, >=85%, >=90%, >=95%, =100% of the area of the carbon fiber fabric segments prior to removal or as originally formed as part of a component).

[0008] It is an object of some aspects of the disclosure to remove resin from carbon fiber strands or carbon fiber fabrics using a vaporized solutions to degrade and remove encasing solidified thermoset resin, e.g. solidified epoxy resins, without damaging carbon fibers either from degrading them or by causing products of the thermoset resin to permanently attach or react with the fibers which might occur, for example, by thermal degradation of the solidified resins as opposed to chemical degradation.

[0009] It is an object of some aspects of the disclosure to break bonds of solidified crosslinked resin without damaging encased carbon fibers to allow separation of the degraded resin from the fibers wherein the bond breaking andAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTseparation use a vapor phase reactive material at a temperature that is above the vaporization temperature of the solution but below a pyrolysis temperature for the solidified resin such that char production is eliminated along with any negative impacts it would have on pristine carbon fiber recycling.

[0010] Some aspects of the disclosure apply a reactive vaporized solution (alternatively a “reactive vapor” or catalyst-containing vapor)) in a reaction chamber (e.g. an autoclave) to the component or components that are being recycled where the vaporized solution is held at a desired temperature (i.e., a single temperature or a plurality7of different temperatures) and a pressure (i.e., single pressure or plurality of different pressures) for a desired period of time (i.e., predefined period of time or time period that is determined via identification of the state of removal (e.g., either from detection of the component itself or change in degradation product removal rate)) to allow sufficient breakdown and removal of the resin to occur yielding a stripped or bare carbon fiber component for further processing.

[0011] In some aspects the stripped or degraded resin is captured and undergoes further processing to complete its recycling for reuse and to remove any catalyst or other solution components, for potential reuse, that were captured in the resin degradation products .

[0012] In some aspects, the vaporized solution may be held in a static or fixed quantify manner while in other aspects the vaporized solution may be flowed, filtered, monitored, and / or refreshed based on estimated changes in composition over time or based on sensed changes in composition such that processing conditions are maintained within a defined process parameter range.

[0013] In some aspects, resin components may be eliminated from the reactive vapor by condensation within the reaction chamber (e.g. at a condensation surface, or container) or may be moved or flowed to a separate condensation chamber for degraded solidified resin product removal and capture (e.g. for recycling). The condensation may result in condensation and separation of reaction products only, the reaction products and part of the vaporized solution, or both of the products and vaporized solution which can then be separated and reconditioned or recycled as appropriate.

[0014] In some aspects, the solution in liquid and / or vapor form may beAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTmoved from the condensation station to a vapor generation station that may or may not include a reconditioning function in preparation for reintroduction of reactive vapor into the reaction chamber.

[0015] After spending a predefined time in the reaction chamber, or a period of time at least partially defined by sensor data coming the component or coming the vapor surrounding the component, the component including wrapped carbon fiber is deemed ready to move to a next stage of the recycling. Sensing may include optical or SEM detection, spectrographic analysis of changes in solidified resin on the component or solidified resin reaction product levels in the vapor or condensed liquid solution, other chemical, or electrical properties of the vapor or condensed liquid, or the like. Sensing may be supplemented with operator analysis and decision making or may proceed in an automated fashion. In some variations decision making may occur via use of a trained machining learning algorithm.

[0016] After resin removal in the reaction chamber, the component including resin stripped carbon fiber may be subjected to further cleaning via a cleaning agent which may include a highly polarized solvent such as (1) water, (2) glycerol, (3) an alcohol, (4) methanol, (5) ethanol, (6) dimethyl sulfoxide, or (7) dimethylformamide. In some aspects the solvent may be (1) water, (2) acetone, (3) alcohol, (4) dimethylformamide, or a combination thereof. This cleaning may target the removal of any residual resin reaction or degradation products and may occur via immersion in a tank containing the cleaning agent, a flow of the cleaning agent, or other gentle relative movement. This cleaning may occur within the reaction chamber or at a separate cleaning station.

[0017] After any supplemental cleaning process in some embodiments, before any supplemental cleaning process in some embodiments, or without any supplemental cleaning process, the carbon fiber of the component is subjected to removal. In the case of a wound carbon fiber (such as that from a high pressure tank, the carbon fiber will be unwound from a liner that it strengthened and then wound on to a spool, tube, or other holder for storage and eventual reuse. In some aspects, the fiber may be directly applied to a new component liner either with or without initial application of a fresh liquid resin binder. In some aspects that winding may occur at a winding station that can handle more than oneAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTstrand, with the winding station also potentially including an unwinding roller or holder for allowing liner or other component rotation, an unwinding guide, a winding roller, a rinse tank with one or more rollers that guide the strand(s) through a rinse tank, NIP roller that provides for rinse agent (e.g. water) removal, potentially other dry ing aids, an actuatable wrapping guide, and a carbon fiber holder or spool roller. The winding station may also include sensors for detecting winding issues, actuators and a controller for providing a desired winding speed or tension, movement control of the wrapping guide, sensor monitoring. Identification and initial grasping of a strand to pull may be handled manually by an operator or automatically by robotic identification, grasping, and control. Spool removal and replacement may also be handled manually or in a robotic manner.

[0018] In the case of recycling carbon fiber sheets, the sheets may have a variety' of sizes and positioning locations, which may require identification of sheet ends that are graspable as well as identification of an optimized removal order. If the sheet locations, sheet sizes, and removal order is known, manual operator grasping and removal may occur, manual grasping and automated removal (with or without supplemental grasping may occur), or automated preprogrammed grasping and removal may occur. If sheet location, size, and removal order is not pre-known, manual operator identification and manipulation may occur, manual identification and robotic manipulation may occur, or automatic identification and robotic manipulation may occur possibly with the aid of a trained machine learning algorithm. Once removed or as part of the removal, individual sheets or fabric segments may be rolled, laid out, or even stacked. Stacking or rolling may potentially include separators located between individual sheets, and potentially7with grasping locations marked for future use.

[0019] In some aspects the elevated temperature may be in the range of 150 °C to 300° C while in others the temperature may be in a narrower range of 180 °C to 250 °C; or even in a narrower range of 180 °C to 200 °C . In some aspects elevated pressure may be in the range of 400 psi to 1000 psi, while in others the pressure may be in the range of 500 psi to 800 psi or even in a narrower range of 500 psi to 600 psi. In still other aspects the pressure may be lower and potentially even as low as atmospheric pressure. In some aspects theAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTspecified reaction duration may be set to a specific value that may fall within a range of, for example: 1 - 48 hours, 2 to 12 hours, or 4 - 8 hours. In some embodiments, longer or shorter reaction durations may be used.

[0020] Some aspects, in addition to treating the component that is to be stripped of hardened resin using a vaporized reactive chemical solution, the component may be contacted with or immersed, in whole or in part, in a liquid reactive chemical solution one or more times to aid in the removal process.

[0021] It is anticipated that some aspects of the disclosure may achieve separation of carbon fibers from encasing hardened resin without use of elevated pressure.

[0022] Some aspects of the disclosure provide separated carbon fibers by winding or spooling them for storage and subsequent usage while others may use a direct unwinding to new component winding or other application process.

[0023] Some aspects provide separated carbon fibers with strengths that are comparable to their original strength, for example the recycled carbon fibers may have strengths that exceed 80% of that of new fibers or even exceeding 85% or 90% while other may be more tolerant of potential fiber damage where strength reductions may as much as 75% but still high enough to allow for high value recycling.

[0024] In some aspects, recycled carbon fibers are collected in continuous lengths where the strands have lengths greater than 25% to 99% of the original carbon fiber length. In some aspects the fibers may have lengths extending from a fraction of a meter (e.g., >= 25 mm, >= 100 mm, or more), to meters (e.g., >= 1 meter, >= 5 meters or more) to tens of meters (e.g. >=10 meters to >=100 meters, or more).

[0025] Some aspects provide for recycling of high pressure vessels and other high pressure storage components whether formed with wound strands or fabrics, as well other components or structures that include encased wound strands or groups of strands or single layers or multiple layers of fabrics whether formed over a permanent base structure or a temporary' base structure (e.g. a liner, mandrel, or other shape preform) that may be retained or removed.

[0026] During work on evaluating resin removal using an autoclave, it was discovered that in the head space of the autoclave, resin degradation wasAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTbeing accomplished with similar results or better results compared to that associated with immersion stripping. This vapor headspace region provided very good quality fiber recovery and with less disruption of the fiber that increased entanglement.

[0027] These vaporized reactive chemical solution aspects provided enhanced ability to effectively work with both larger and smaller components, parts, or structures. The ability to recycle large structures or components eliminates or reduces the need to cut down these elements prior to recycling thus maximizing the ability to recover longer fibers and large fabrics segments bringing higher value and increased reuse possibilities.

[0028] Some aspects of the disclosure provide for catalytic depolymerization of cured epoxy systems using mild chemistries (e.g. weak acids, e.g. weak organic acids, used as swelling agents with potentially the same weak acids or different materials being used as catalysts) within a vapor space (e g. the head space of an autoclave without being submerged in a liquid solution. It is believed that some aspects may operate at ambient pressure with elevated temperature. Some aspects may operate in a continuous process. Some aspects may also provide for recovery7and reuse of the reactive vapor phase material.

[0029] Some aspects provide methods of recycling while others provide recycling systems. Some aspects may be executed manually while others may be implemented with varying degrees of automation including use of sensors, actuators, pumps, heaters, coolers, filters, other material separators, and manipulators in conjunction with manual operation or programed controllers operating in an open loop manner, a partially closed loop manner, or in a fully closed loop manner.

[0030] Some aspects may provide for recycling of only long strand carbon fibers or large fabric segments of carbon fiber sheets while other aspects may also provide for recycling of degraded solidify resin reaction products, capturing and reusing of catalysts, reactive chemicals, and the like.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings illustrate generally, by way of example, but not byAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTway of limitation, various embodiments of the present invention.

[0032] FIG. 1 is a schematic view of a system for winding a epoxy¬ coated fiber strand onto a pressure vessel or other component.

[0033] FIG. 2 provides a photograph of a pressure vessel after winding an epoxy coated fiber strand around it and curing the epoxy.

[0034] FIG. 3 provides a schematic depiction of a reaction chamber for stripping epoxy from a carbon fiber composite.

[0035] FIG. 4 provides a photograph of a composite epoxy pressure vessel after stripping epoxy from the wound carbon fiber revealing the carbon fiber.

[0036] FIG. 5 provides a schematic illustration of a washing station used for removed residual catalyst and swelling agent from a carbon fiber composite after the epoxy has been stripped away.

[0037] FIG. 6 is a schematic view of a fiber strand unwinding and winding system that includes an intermediate resin washing station.

[0038] FIG. 7 provides a photograph of a recycled carbon fiber wrapped around a cardboard tube that was prepared by using the system of FIG. 6 on a vessel like that shown in FIG. 4.

[0039] FIG. 8 is a graph showing tensile strength data of a pristine fiber compared to a recycled fiber.DETAILED DESCRIPTION

[0040] Various advantages and novel features of the present disclosure are described herein and will become further readily apparent to those skilled in this art from the following detailed description. In the preceding and following descriptions the preferred aspect of the disclosure is shown by way of illustration of the best mode contemplated for carrying out the disclosure . As will be realized, the disclosure is configured to be modified in various respects without departing from the spirit of the disclosure as will be understood by those of skill in the art from the claims set forth herein, the aspects set forth herein, and the variations in the aspects.

[0041] The following terms have the following meaning when used in this application except at those locations wherein such terms are used inAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTcombination with additional information that unambiguously provides a different meaning:

[0042] “About”, “about”, or “substantially” when referring to defined, measurable, or controllable amounts or values are intended to encompass variations of and from the amounts or values that are up to + / - 15% or less, + / -10% or less, + / - 5% or less, + / - 1 % or less to the extent that such variations allow for the disclosure or aspect of the disclosure to meet functional, configurational, compositional, and any other operational requirements.

[0043] Continuous carbon fiber strand means a carbon fiber with a length > 25 millimeters (mm), > 10 centimeters (cm), => 1 meter (m), => 10 m, or => 100 m.

[0044] Continuous carbon fiber fabric segment means a carbon fiber fabric sheet with an area >= 20 cm2, >= 200 cm2, >= 2000 cm2, or >= 2m2.

[0045] Degraded solidified resin products, degradation products, reaction products, and the like means oligomers extracted from a polymer where the oligomers have a weight average molecular weight of less than 2000 Da.

[0046] In an undamaged state of a fiber means the retention of one or more original intrinsic mechanical properties (e.g. strength, stiffness) of the fiber that is >= 50%, >= 70%, >85%, >= 90%, or >= 95% of that of an equivalent new fiber. Generally stronger or stiffer carbon fibers can withstand more damage during recycling and still be usefulness as higher value recycled products.

[0047] Existing recycling methods include various pros and cons. For example, mechanical recycling is low cost and involves low energy processing; however, long high quality fibers are reduced to short fibers and fillers which offer minimal high performance value in reuse. Thermal recycling uses pyrolysis which reduces organic resin material to carbon (ash) to recover the fibrous material. Pyrolysis is more energy intensive and can damage the fiber depending the fiber type and pyrolysis conditions; however, the process can be continuous and can be performed on large parts or components. Finally, chemical or solvolysis recycling may or may not use more energy than mechanical recycling but has limits on what can be done with cured resins. Solvolysis is moreAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTcommonly used on uncured resin systems with the resin being cleaned from the fiber. The state of the art in practice when resins are cured usually involves use of aggressive bases and acids that can damage fibers.

[0048] Some resin removal / recycling processes have been proposed that use fairly mild liquid catalysts solution that do not tend to chemically damage fiber structures but can lead to other issues that make continuous strand or fabric form recycling of fibers less efficient or effective. Such teachings are found, for example, in US Patent 10,696,815, issued June 30, 2020, by Zhang et al. of Washington State University which teaches use of chemical degradation of epoxies using aqueous liquid solutions containing organic salts as cataly sts. The patent provides example solutions and chemistries and is incorporated herein by¬ reference as if set forth in full.

[0049] An aspect of the recycling processes described herein involves the use of vaporized reactive chemical solutions to degrade solidified thermoset resins while preserving the structural integrity of embedded fibers. This vapor phase approach represents a departure from conventional liquid immersion techniques and offers distinct advantages in terms of fiber quality, process efficiency, and scalability. The vapor phase environment allows for substantially uniform exposure of composite components to reactive chemicals while minimizing fiber entanglement and mechanical disruption that can occur with liquid phase processing.

[0050] The vapor phase recycling process may be conducted in a reaction chamber of a system for the process, which in various configurations may include an autoclave, a sealed vessel, a pressurizable container, or other suitable enclosure configured to maintain controlled temperature and pressure conditions. The reaction chamber provides a space where composite components can be exposed to reactive vapor without requiring submersion (either partial or complete) in liquid. In certain configurations, the composite component may be suspended in a headspace region above a reservoir of reactive chemical solution, with the vapor generated from the reservoir filling the headspace and contacting the component surfaces.

[0051] The discovery that resin degradation in the vapor headspace of a reaction chamber can achieve results comparable to or superior to liquidAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTimmersion represents an advancement. Fiber components processed in vapor phase environments may demonstrate superior fiber quality, compared to other recovery means, and may include comparatively reduced fraying, less fiber entanglement, and more complete resin removal. The vapor phase approach also facilitates processing of larger components without requiring sectioning or disassembly, thereby maximizing the length of recoverable continuous fibers. This vapor headspace processing, where the component is positioned above or at least not completely submerged in the liquid reactive chemical solution and exposed predominantly or exclusively to reactive vapor rather than being immersed in liquid, provides unexpectedly beneficial results that form the foundation of the recycling approaches described throughout this disclosure.

[0052] The recycling processes and systems described herein may be applied to a wide variety of composite components. Pressure vessels represent one category' of suitable components, including composite overwrapped pressure vessels (COPVs) used for storage of compressed gases such as hydrogen, natural gas, or other fluids. These pressure vessels, as an example, may include continuous carbon fiber strands wound in helical, hoop, or combined winding patterns over a liner, which may be metallic such as aluminum or steel, or polymeric such as high-density polyethylene or other suitable materials. The substantial carbon fiber content of these vessels, combined with their defined service lives and the growing market for hydrogen storage infrastructure, makes pressure vessel recycling particularly valuable.

[0053] High pressure tubes and pipes constitute another category' of components amenable to the recycling processes described herein. These tubular structures may incorporate filament wound fibers or fabric layers and find application in fluid transport systems, structural supports, or other engineering applications. Wind turbine blade components represent yet another category , which typically comprise large fabric layups or unidirectional fiber arrangements embedded in epoxy or other thermoset resins. The large size of wind turbine blades, which can exceed 50 meters or even reach 80 meters or more in length, makes the ability to process large components without extensive sectioning particularly advantageous.

[0054] Automotive components including body panels, structuralAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTreinforcements, drive shafts, and other parts may also be processed using the described recycling techniques. The automotive sector's growing use of composites for lightweighting, particularly with the expansion of electric vehicle production, creates an expanding source of composite waste for recycling. Aerospace components, sporting goods, marine structures, and infrastructure elements such as bridge reinforcements or building structural members may also serve as suitable feedstock for the recycling processes.

[0055] The processing may be applied to composite manufacturing waste including expired prepreg materials, trim scrap from component fabrication, or out-of-specification components in addition to end-of-life components from service. Manufacturing waste often contains uncured or partially cured resin that may be even more readily removed than fully cured resin, though the vapor phase processes work effectively with fully cured thermoset resins as well. The ability to recycle manufacturing waste provides value even in ongoing production environments and reduces the environmental footprint of composite manufacturing operations. This manufacturing waste recycling capability complements end-of-life component recycling, providing composite manufacturers with options for managing multiple waste streams through a common recycling approach. None of these examples is to be construed as limiting.

[0056] The components may vary in size from small parts measuring centimeters in dimension to large structures measuring meters or tens of meters in their longest dimension. Components may incorporate single layers or multiple layers of fiber reinforcement, with layer counts ranging from 1 layer to 2 layers, 3 layers, 4 layers, 5 layers, 10 layers, 20 layers, 50 layers, 100 layers, or more than 100 layers, depending on the application requirements. The vapor phase processing approach accommodates this wide range of component sizes and configurations, providing flexibility in feedstock acceptance.

[0057] Carbon fibers represent one fiber type for recovery using the described processes. Carbon fibers suitable for recovery may include polyacrylonitrile (PAN)-based carbon fibers, pitch-based carbon fibers, rayonbased carbon fibers, or other carbon fiber ty pes. The carbon fibers may have various tensile strengths, moduli, and diameters depending on their grade andAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTintended application. High strength carbon fibers, intermediate modulus carbon fibers, high modulus carbon fibers, and ultra-high modulus carbon fibers may all be successfully recovered through the vapor phase degradation approach.

[0058] The carbon fibers may be configured as continuous strands, also referred to as tows, which comprise bundles of individual carbon filaments. In non-limiting examples, tow sizes may range from IK (1,000 filaments) to 3K, 6K, 12K, 24K, 48K, 50K, 80K, 100K, or even larger tow sizes exceeding 100K filaments. The specific example of AS4C-12K carbon fiber tows, comprising 12,000 filaments per tow, represents one commonly used industrial carbon fiber format. Individual fiber diameters may, in non-limiting examples, range from 3 micrometers to 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers. 8 micrometers, 9 micrometers, 10 micrometers, 12 micrometers, 15 micrometers, or fall within ranges such as 3 to 15 micrometers, 4 to 12 micrometers, 5 to 10 micrometers, or 6 to 8 micrometers.

[0059] In addition to continuous strand configurations, carbon fibers may be arranged in fabric forms including woven fabrics, non-woven fabrics, unidirectional fabrics, braided fabrics, or knitted fabrics. Fabric architectures may include plain weave, twill weave, satin weave, or more complex three-dimensional woven structures. In non-limiting examples, fabric areal weights may range from 25 grams per square meter (gsm) to 50 gsm, 100 gsm, 200 gsm, 300 gsm, 400 gsm, 600 gsm, 800 gsm, 1000 gsm, 1500 gsm, 2000 gsm, or fall within ranges such as 50 to 2000 gsm, 100 to 1500 gsm, 200 to 1000 gsm, or 300 to 600 gsm.

[0060] While carbon fibers represent a focus area, the processes may also be applied to other fiber types including glass fibers such as E-glass, S-glass, C-glass, or other glass compositions. Aramid fibers such as Kevlar or Nomex, basalt fibers, natural fibers including flax or hemp, or hybrid combinations of different fiber t pes may also be processed. The versatility of the vapor phase approach allows adaptation to various fiber chemistries provided the processing conditions are selected to avoid fiber degradation. Each fiber type may have different thermal and chemical resistance characteristics, and processing parameters can be adjusted accordingly to optimize resin removal while maintaining fiber integrity.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0061] The solidified thermoset resins subject to degradation and removal in the described processes encompass various resin chemistries. Epoxy resins represent one category, including bisphenol A epoxies such as DGEBA (diglycidyl ether of bisphenol A), bisphenol F epoxies, novolac epoxies, aliphatic epoxies, cycloaliphatic epoxies, and glycidyl ester epoxies. The example of Epon 826 epoxy resin represents one commercially available epoxy system. Epoxy resins may be cured with various curing agents including aliphatic amines such as Jeffamine T-403 as exemplified, aromatic amines, cycloaliphatic amines, polyamides, anhydrides, or catalytic curing systems. The crosslink density of cured epoxy systems may vary widely depending on the epoxy functionality and curing agent selection, with higher functionality’ monomers and curing agents producing more highly crosslinked networks.

[0062] Polyurethane thermosets are another example of a category of resins applicable to the described recycling processes. Polyurethanes may be formed from reactions of polyols with isocyanates, with crosslinking achieved through the selection of multifunctional reactants. Other thermoset systems that may be processed include unsaturated polyesters, vinyl esters, phenolic resins, bismaleimides, polyimides, cyanate esters, or benzoxazines. The resin systems may be formulated with various additives, including toughening agents, flame retardants, UV stabilizers, colorants, or other functional additives, all of which become part of the degradation product stream during processing.

[0063] The degree of cure in the thermoset resin may vary’ from partially cured states to fully cured states. In certain cases, the resin may have undergone post-curing treatments that result in highly crosslinked networks with elevated glass transition temperatures. In non-limiting examples, the glass transition temperature of the cured resin may' range from 40°C to 60°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, 220°C, 250°C, 280°C, 300°C, 350°C, or fall within ranges such as 50°C to 300°C, 100°C to 280°C, 150°C to 250°C. or 180°C to 220°C. Higher glass transition temperatures generally indicate more highly crosslinked or more rigid network structures, which may require longer processing times or more aggressive processing conditions for complete degradation and removal.

[0064] The reactive chemical solutions (which become the reactiveAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTvapor) employed in the vapor phase recycling processes comprise catalyst solutions and may also include polymer swelling materials that, when together, work synergistically to degrade the crosslinked thermoset networks and leave the fiber. In some examples, the reactive chemical solution may only include the catalyst and not include the polymer swelling material. The catalyst solutions include catalysts dissolved in suitable solvents at concentrations that provide effective catalytic activity' while maintaining processability. Catalyst concentrations may range from 10 wt.% to 60 wt.%, 15 wt.% to 40 wt.%, 20 wt.% to 30 wt.%, or 18 wt.% to 25 wt.% 5 wt.% to 10 wt.%, less than, equal to, or greater than about 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, or 60 wt.%, based on the total weight of the catalyst solution.

[0065] Catalysts suitable for use include metal salts wherein the metal cation provides Lewis acid character that facilitates cleavage of bonds in the crosslinked resin network. Zinc salts such as zinc acetate, zinc chloride, zinc formate, zinc propionate, or zinc octoate may be employed. The use of zinc acetate in aqueous solution represents one demonstrated formulation. Iron salts including ferric acetate, ferric chloride, ferrous acetate, or ferrous sulfate represent alternatives that may provide different catalytic activities or selectivities. Copper salts such as cupric acetate, cupric chloride, cuprous acetate, or cuprous chloride may also function as catalysts. Additional suitable metal cations include chromium in +2 or +3 oxidation states, manganese in +2 or +3 oxidation states, cobalt in +2 or +3 oxidation states, nickel in +2 or +3 oxidation states, tin in +2 or +4 oxidation states, and lead in +2 or +4 oxidation states, each offering potentially different catalytic behavior that may be advantageous for certain resin types.

[0066] The anion component of the metal salt may be selected from acetate, formate, propionate, butyrate, octoate, ethanedioate (oxalate), or organic sulphonic acid ions such as methanesulfonate or p-toluenesulfonate. The anion selection may influence both the solubility of the metal salt in the chosen solvent and the overall effectiveness of the catalytic system. In certain configurations, inorganic salts such as aluminum chloride, boron trifluoride, or titanium tetrachloride may serve as catalysts, offering strong Lewis acidity. Base catalysts such as sodium hypochlorite (NaOCl) or tripotassium phosphate may beAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTemployed in alternative formulations where base-catalyzed degradation mechanisms are advantageous. In other configurations, the catalysts may include organic acids, and more particularly weak organic acids or weak carboxylic acids such as acetic acid or formic acid which may be directly supplied and mixed into a solvent or be formed from, for example acetate being mixed in a solvent, e.g. water, to form acetic acid. In some examples, the weak organic acids may be in glacial form or anhydrous form. As generally understood, a weak organic acid is an acid that contains carbon in its structure and only partially dissociates in water, meaning it does not release all of its hydrogen ions. This results in a relatively low concentration of free protons compared to strong acids. In some examples, it is possible for the catalysts to include a weak inorganic acid.

[0067] Solvents for the catalyst solutions include highly polarized solvents that facilitate dissolution of the catalyst and provide a medium for vapor generation. Water represents one solvent choice due to its polarity, availability, safety profile, and environmental compatibility. The use of water as the primary solvent in the demonstrated formulation exemplifies this approach. Glycerol may serve as an alternative or supplementary7solvent, offering higher boiling point and different solvation properties. Alcohols including methanol, ethanol, propanol, isopropanol, butanol, or higher alcohols may be employed, either alone or in combination with water. Dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) represent additional polar aprotic solvent options that may be particularly effective for certain resin types. Mixed solvent systems comprising combinations of two or more solvents may also be utilized to tailor vapor pressure, boiling point, and solvation characteristics to specific processing requirements.

[0068] The solvent component may range from about 50 wt.% to 95 wt.%, 60 wt.% to 90 wt.%, 70 wt.% to 85 wt.%, 75 wt.% to 85 wt.%, or 78 wt.% to 82 wt.%, less than, equal to, or greater than about 50 wt.%, 60 wt.%, 70 wt.%, 75 wt.%, 80 wt.%, 85 wt.%, 90 wt.%, 95 wt.% of the catalyst solution. In some examples, an aqueous zinc acetate solution may comprise about 80 wt.% water and about 20 wt.% zinc acetate, or may comprise water in a range of 75 wt.% to 85 wt.%, 77 wt.% to 83 wt.%, or 78 wt.% to 82 wt.% and zinc acetate in a rangeAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTof 15 wt.% to 25 wl.%, 17 wl.% to 23 wt.%, or 18 wl.% to 22 wl.%.

[0069] Polymer swelling materials function to swell the crosslinked resin network of the polymer, thereby facilitating penetration of the catalyst into the resin matrix and enhancing the rate of bond cleavage. Acetic acid represents a suitable polymer swelling material that exhibits good miscibility with aqueous catalyst solutions and effective swelling behavior with epoxy resins. The demonstrated use of acetic acid at about 10 wt.% in the overall reactive chemical solution exemplifies this approach. In some examples, citric acid may serve as an alternative, providing multifunctional acid groups that can interact with the resin network through multiple sites. Formic acid, being a smaller molecule, may provide enhanced penetration into tightly crosslinked networks where steric effects limit access of larger molecules. Nitric acid (HNOJ) represents another option, though care may be taken to avoid concentrations or conditions that might lead to fiber damage, particularly with certain fiber types that may be sensitive to strong oxidizing conditions.

[0070] The polymer swelling component may range from about 10 wt.% to 70 wt.%, 15 wt.% to 50 wt.%, 20 wt.% to 40 wt.%, 8 wt.% to 12 wt.%, or 9 wt.% to 11 wt.%, 5 wt.% to 10 wt.%, less than, equal to, or greater than about 15 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, of the total reactive chemical solution. The catalyst solution component may range from about 30 wt.% to 90 wt.%, 50 wt.% to 85 wt.%, 70 wt.% to 80 wt.%, 68 wt.% to 72 wl.%, or 85 wt.% to 90 wt.%, less than, equal to, or greater than about 30 wt.% to 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, 80 wl.%, 90 wt.%, as of the total reactive chemical solution depending on the desired balance between catalyst loading and swelling agent loading. In some variations a single material may be used as a swelling agent and as the catalyst, such as for example acetic acid or formic acid with the amount of the material supplied at such a level being selected to effectively provide both functions.

[0071] In some examples, the reactive chemical solution may comprise about 70 wt.% water, about 20 wt.% zinc acetate, and about 10 wt.% acetic acid. This formulation has been demonstrated to provide effective resin degradation with good fiber recovery and quality. Alternative formulations may comprise water in a range of 60 wt.% to 80 wt.%, 65 wt.% to 75 wl.%, or 68 wt.% to 72Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTwt.%, zinc acetate in a range of 15 wt.% to 25 wt.%, 18 wt.% to 22 wt.%, or 19 wt.% to 21 wt.%, and acetic acid in a range of 5 wt.% to 15 wt.%, 8 wt.% to 12 wt.%, or 9 wt.% to 11 wt.%. Other formulations may comprise different catalyst and swelling agent combinations while maintaining similar total composition ranges, such as substituting ferric acetate for zinc acetate or substituting citric acid for acetic acid. Some alternative formulations may include, for example acetic acid and water without a separate swelling agent or separate catalyst wherein the acetic acid may range from as low as 1% to as much as 100% and water alone or in combination with other solvents ranging from 0% to 99%, in other embodiments the acetic acid may have a weight percent >= 1 %, >= 2%, >= 4%. >= 5%. >= 10%, >= 20%, >= 40%, >= 60%, >= 80%. In some embodiments, the acetic acid may be provided in an amount lower <= 95%, <= 90%, <= 85%, or <= 80% with water or another solvent making up the majority, vast majority, or all of the remaining portion of the reactive chemical solution.

[0072] Various combinations of catalysts, polymer swelling materials, and solvents have been evaluated for effectiveness in thermoset resin degradation. Formulations comprising acetic acid, zinc acetate and / or zinc chloride and / or aluminum chloride, and w ater have been observed to provide effective resin degradation with good fiber recovery in vapor phase processing. Degradation has also been observed with only acetic acid and water with acetic acid providing both a catalytic and swelling effect. Formulations comprising benzy l alcohol and potassium triphosphate have demonstrated effective resin degradation under ambient pressure Certain formulations that have been evaluated, such as glycerol with zinc acetate, or citric acid with water, and found to be less effective for certain resin systems or processing conditions. Highly aggressive acids such as hydrochloric acid, or strong concentrations of nitric acid, while potentially effective for resin degradation, may pose fiber damage risks or handling challenges that make alternative formulations more suitable for practical implementation.

[0073] In a recycling system employing the methods described herein, the reaction chamber serves as the location where vapor phase resin degradation occurs and represents a central component of the recycling systems described herein. In various configurations, the reaction chamber may include a pressureAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTvessel, an autoclave, a sealed tank, a cylindrical chamber, a rectangular chamber, or other geometry suited to the size and shape of components being processed. In non-limiting examples, the chamber dimensions may be selected based on the components to be processed, with internal volumes ranging from 0.5 liters to 1 liter, 5 liters, 10 liters, 20 liters, 50 liters, 100 liters, 500 liters, 1000 liters, 5000 liters, 10,000 liters, 20,000 liters, or larger volumes such as 50,000 liters or more for industrial scale operations. Larger chambers accommodate larger components or allow batch processing of multiple components simultaneously, while smaller chambers may be suitable for research, development, or small-scale recycling operations.

[0074] The reaction chamber includes at least one location for positioning composite components to be recycled. This location may include a support structure, suspension apparatus, rack, platform, or other fixture that maintains the component in a desired fixed orientation, varying orientation, or rotating orientation during processing. A rate of rotation or a rotation amount and delay period be selected to allow onentation positions to be held for periods that allow run off or drip off of byproducts perhaps in combination with condensed reactive solution. In some implementations a reaction location for a component may be translated between different positions in the chamber to allow improved batch processing, continuous processing, or semi -continuous processing with a defined loading location, and / or unloading location which may be temporarily isolated from other chamber locations to avoid completely stopping chamber operation or vapor maintenance during component loading and unloading. In configurations where vapor phase processing in a headspace is utilized, the component positioning location places the component above any reservoir of reactive chemical solution, thereby exposing the component primarily or exclusively to vapor rather than liquid.

[0075] In non-limiting examples, the vertical distance between the liquid surface and the component may be selected to ensure adequate vapor circulation while avoiding direct liquid contact. As non-limiting examples, this separation distance may range from 0.5 centimeters to 1 cm, 2 cm, 5 cm, 10 cm, 15 cm, 20 cm, 30 cm, 40 cm, 50 cm, 75 cm, 100 cm, 150 cm, or fall within ranges such as 0.5 cm to 150 cm, 1 cm to 100 cm, 5 cm to 75 cm. 10 cm to 50 cm, or 15 cm toAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT30 cm. For larger reaction chambers, separation distances may extend to 2 meters or more. The component may be suspended, for example, using support rods, cables, chains, brackets, or other mechanical supports fabricated from materials resistant to the reactive chemical environment such as stainless steel, titanium, ceramic materials, high-temperature alloys, or chemically resistant polymers such as polytetrafluoroethylene (PTFE) or perfluoroalkoxy (PF A) materials.

[0076] The reaction chamber may further include at least one location for collecting degraded resin reaction products. This may include a condensation surface, a collection tray, a drainage port, or a recirculation line that directs condensed material to a separate collection vessel. The collection location may be positioned at a lower region of the chamber to take advantage of gravity-driven drainage. In certain configurations, the reaction chamber may include baffles, deflectors, or surface treatments that promote condensation of resin degradation products while maintaining the reactive vapor in a vaporized state. The deliberate design of condensation zones allows selective removal of degradation products without substantially depleting the reactive vapor components, thereby maintaining process effectiveness over extended operating periods. In some implementations a collection location may be located in a separate chamber that is separated from the reaction chamber with one or more connected flow passages which may be continuous open or be periodically opened and closed as processing occurs. In some implementations, fresh reactive solution or vapor may be added to the reaction chamber in a continuous or discontinuous manner in conjunction with removal of byproducts, exposed reactive solution or vapor, and / or partially or fully byproduct saturated solution or vapor.

[0077] Temperature control within the reaction chamber may be achieved, for example, through external heating elements, internal heating elements, heated jacket designs, circulation of heated fluids through chamber walls, heat solution or vapor that is flowed through the reaction chamber.Heating elements may comprise electric resistance heaters, induction heaters, infrared heaters, or heated fluid circulation systems using oil, steam, or other heat transfer fluids. Temperature sensors positioned at various locations withinAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTthe chamber monitor temperature and provide feedback to a control system that adjusts heating or fluid flow The temperature is also maintained in a range the provides an adequate reaction rate while not exceeding breaking down temperature or other process hindering changes in operation of the reactive solution. In some implementations, a balance between sufficient temperature for vapor generation and chemical reactivity, while avoiding excessive temperature that would cause pyrolysis, guides temperature selection for different resin systems and component configurations.

[0078] Suitable specified reaction temperatures may range from 120°C to 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 350°C, or temperatures up to 400°C depending on the resin system and chemical solution employed. The demonstrated processing at 240°C for the composite overwrapped pressure vessel example falls within these ranges and illustrates effective processing conditions. More narrowly, temperature ranges may include 150°C to 300°C, 150°C to 280°C, 150°C to 260°C, 160°C to 280°C, 170°C to 270°C, 180°C to 250°C, 180°C to 240°C, 180°C to 230°C, 180°C to 220°C, 180°C to 210°C, 180°C to 200°C, 190°C to 250°C, 200°C to 240°C, 210°C to 230°C, 220°C to 260°C, or 235°C to 245°C.

[0079] Individual temperature setpoints may include 180°C. 190°C. 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, or 280°C. In certain processing scenarios, the temperature may be maintained at a substantially constant value throughout the reaction period, providing steady-state conditions that simplify process control and ensure consistent results. In alternative scenarios, the temperature may be varied during processing, such as by employing a temperature ramp from a lower initial temperature such as 150°C or 160°C to a higher processing temperature such as 230°C or 240°C, maintaining a plateau at the processing temperature for the bulk of the reaction period, and then cooling at the end of processing. Multi-step temperature profiles may also be employed, such as initial processing at a first temperature such as 200°C for a first period, followed by processing at a second temperature such as 230°C for a second period, allowing sequential degradation stages that may target different bond types or resin regions.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0080] The selected temperature(s) remains sufficiently below the pyrolysis temperature of the thermoset resin being processed. For epoxy resins, pyrolysis typically begins at temperatures above 350°C to 400°C or even higher temperatures such as 450°C, though this varies with the epoxy chemistry, curing agent type, and degree of cure. More highly crosslinked epoxies generally exhibit higher pyrolysis onset temperatures. The processing temperature is therefore maintained at least 50°C, at least 75°C. at least 100°C, at least 125°C, at least 150°C, at least 175°C, or at least 200°C below the pyrolysis onset temperature. Alternatively expressed, the processing temperature may be maintained in a range of 50°C to 250°C below the pyrolysis onset temperature, 75°C to 200°C below, 100°C to 180°C below, or 120°C to 160°C below. This temperature margin helps ensure that resin degradation proceeds through chemical bond cleavage facilitated by the catalyst rather than thermal decomposition, thereby helping to avoid char formation and helping to preserve fiber surface cleanliness.

[0081] The specified reaction pressure influences the vaporization behavior of the reactive chemical solution and may affect the rate and completeness of resin degradation. In certain configurations, elevated pressure is employed to maintain higher temperatures while keeping the reactive chemicals in a vapor state and to enhance the penetration of reactive species into the resin matrix. The relationship between temperature and pressure follows thermodynamic principles, with higher pressures allowing higher temperatures to be reached while maintaining liquid-vapor equilibrium or subcooled liquid conditions that can readily generate vapor.

[0082] Examples of suitable specified reaction pressures may range from atmospheric pressure (about 0.1 MPa) to 0.2 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, 7 MPa, 8 MPa, or higher pressures such as 10 MPa, 12 MPa, or 15 MPa. More narrowly, pressure ranges may include 2.5 MPa to 7 MPa, 2.5 MPa to 6.5 MPa, 2.5 MPa to 6 MPa, 3 MPa to 7 MPa, 3 MPa to 6.5 MPa, 3.5 MPa to 7 MPa, 3.5 MPa to 6 MPa, 3.5 MPa to 5.5 MPa, 3.5 MPa to 5 MPa, 3.5 MPa to 4.5 MPa, 4 MPa to 6 MPa, 4.5 MPa to 5.5 MPa, 3.8 MPa to 4.5 MPa, or 4 MPa to 4.8 MPa.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0083] Individual pressure setpoints may include, for example, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, or 7 MPa. The pressure may be maintained at a substantially constant level throughout the reaction period, providing stable processing conditions. Alternatively, the pressure may be varied during processing. In certain processing scenarios, an initial lower pressure may be employed during heat-up, followed by increasing pressure as the system reaches the target temperature. This staged pressure approach can help manage vapor generation rates and prevent overly rapid vapor formation during heat-up. Multi-stage pressure profiles may also be utilized, such as processing at a first pressure during an initial degradation period followed by processing at a second different pressure during a final degradation period.

[0084] In alternative examples, the recycling process may be conducted at atmospheric pressure or pressures only slightly above atmospheric, such as 0.11 MPa to 0.15 MPa, 0.11 MPa to 0.2 MPa, 0.11 MPa to 0.25 MPa, or 0.12 MPa to 0.18 MPa. Atmospheric or near-atmospheric pressure processing may be suitable for certain resin-fiber combinations and offers advantages in terms of equipment simplicity7, lower capital costs, and enhanced safety7. The selection between elevated pressure and atmospheric pressure processing depends on factors including the resin chemistry and crosslink density, the desired processing time, the chemical solution composition and vapor pressure, and the component geometry and size. Lowber cure resins or resins with low er crosslink density may be effectively processed at atmospheric pressure with appropriate temperature and time selection.

[0085] The specified reaction duration required for effective resin removal depends on multiple factors including the resin type and degree of cure, the component thickness and geometry, the chemical solution composition, the processing temperature, and the processing pressure. These factors interact in complex ways, with higher temperatures generally reducing required processing times, higher catalyst concentrations accelerating reactions, and thicker components requiring longer times for vapor penetration and complete resin degradation throughout the thickness.

[0086] Suitable specified reaction durations may range from 30 minutesAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTto 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours. 8 hours, 9 hours. 10 hours, 12 hours, 16 hours, 20 hours, 24 hours, 30 hours, 36 hours, 42 hours, 48 hours, 60 hours, 72 hours, or longer times such as 96 hours or 120 hours for challenging components. The demonstrated processing time of 5 hours for the composite overwrapped pressure vessel example illustrates one effective processing duration. More narrowly, time ranges may include, for example, 1 hour to 48 hours, 1 hour to 36 hours, 1 hour to 24 hours, 2 hours to 48 hours, 2 hours to 36 hours, 2 hours to 24 hours, 2 hours to 16 hours, 2 hours to 12 hours, 3 hours to 12 hours, 4 hours to 12 hours, 4 hours to 10 hours, 4 hours to 8 hours, 4.5 hours to 6 hours, 5 hours to 10 hours, or 6 hours to 8 hours.

[0087] Individual specified reaction durations may include 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or 12 hours. In certain processing scenarios, a fixed predetermined specified reaction duration is employed based on prior characterization of similar components. This approach provides operational simplicity and predictability. In alternative scenarios, the specified reaction duration is determined dynamically based on monitoring of the degradation process, allowing optimization for each individual component or batch. Sensors may detect changes in component appearance, changes in vapor composition, changes in condensate composition or generation rate, or other indicators that sufficient resin removal has been achieved.

[0088] In some examples, optical sensors may monitor surface reflectivity', color, or texture changes of the component as resin is removed and fiber becomes exposed. Spectroscopic sensors including infrared, near-infrared. Raman, or fluorescence spectroscopy may analyze the component surface or the vapor composition to detect resin degradation products. Chemical sensors may detect concentration changes of certain chemical species in the vapor or condensate. Mass sensors may track the rate of mass loss from the component or mass accumulation in condensate collection systems. Temperature sensors may detect exothermic or endothermic effects associated with degradation reactions, as bond breaking and forming processes involve heat effects. The sensor data may be processed by a controller that determines when sufficient resin removal has occurred based on predefined criteria, threshold values, or machine learningAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTalgorithms trained on prior processing runs.

[0089] The reactive vapor is generated by heating the reactive chemical solution to temperatures above its vaporization point while maintaining pressure conditions suitable for vapor formation. In configurations where a liquid reservoir is present in the reaction chamber, the vapor is generated from this reservoir as the chamber temperature increases. The vapor rises and fills the headspace region of the chamber, contacting the suspended composite component. This headspace vapor exposure, rather than liquid immersion, provides effective resin degradation while minimizing mechanical disruption of the fibers and represents a distinguishing feature of the recycling approaches described herein.

[0090] The vapor composition in the headspace reflects the composition of the liquid solution, though fractional distillation effects may result in some enrichment or depletion of certain components depending on their relative volatilities. The vapor pressure of the solution components and the total system pressure determine the vapor composition at equilibrium. In certain configurations, the vapor generation rate and composition may be monitored and controlled through adjustment of the heating power, pressure settings, or solution composition. Real-time monitoring allows dynamic adj ustment to maintain optimal vapor conditions throughout the processing cycle.

[0091] In alternative configurations, vapor may be generated in a separate vaporization vessel and introduced into the reaction chamber through inlet ports, nozzles, or distribution manifolds. This separated vapor generation approach allows for more precise control over vapor composition, temperature, and flow rate. The vaporization vessel can be optimized for efficient vapor generation with appropriate heating capacity and liquid surface area, while the reaction chamber can be optimized for component processing with appropriate size and geometry. The vapor may be superheated to temperatures above the saturation temperature at the operating pressure, such as I0°C to 20°C, 30°C, 50°C, or more above saturation temperature, to provide additional thermal energy for the degradation reactions and to reduce condensation on component surfaces or chamber walls.

[0092] The reactive vapor may be maintained in a static or substantiallyAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTstatic condition within the chamber, with natural convection providing circulation around the component. Natural convection arises from density differences in the vapor caused by temperature gradients, with hotter less-dense vapor rising and cooler more-dense vapor descending. Alternatively, forced circulation may be employed using fans, blowers, pumps, or eductor systems that create directional vapor flow. Circulating the vapor promotes more uniform exposure of component surfaces, reduces concentration gradients of reactive species and degradation products, and may accelerate the overall degradation process by continuously supplying fresh reactive vapor to component surfaces and removing degradation product-laden vapor.

[0093] In non-limiting examples, vapor flow velocities may range from 0.05 meters per second to 0.1 m / s, 0.5 m / s, 1 m / s, 2 m / s, 3 m / s, 5 m / s, 10 m / s, 15 m / s, 20 m / s, or fall within ranges such as 0.1 m / s to 20 m / s, 0.5 m / s to 15 m / s, 1 m / s to 10 m / s, or 2 m / s to 8 m / s. The flow direction may be unidirectional, bidirectional, or multidirectional, with flow patterns designed based on component geometry and chamber configuration. Flow patterns may be configured to minimize stagnant regions and help ensure all component surfaces receive adequate vapor exposure. In certain configurations processing larger or more complex shaped components, multiple inlet and outlet ports may be positioned at different locations to achieve desired flow patterns, such as upward flow along one side of a component and downward flow' along another side to create circulation loops.

[0094] As the thermoset resin undergoes chemical degradation in the vapor headspace environment, oligomeric and monomeric degradation products are released from the solid resin matrix and enter the vapor phase. These degradation products, having molecular weights typically less than 2000 Daltons, less than 1500 Daltons, less than 1000 Daltons, less than 750 Daltons, or less than 500 Daltons, possess different volatilities compared to the original reactive chemical solution components. The accumulation of degradation products in the vapor phase may eventually reduce the effectiveness of the degradation process if allowed to continue unchecked, as the partial pressure of reactive vapor components decreases and equilibrium effects slow the degradation kinetics.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0095] To address this accumulation, in some examples, condensation systems may be employed to selectively remove degradation products from the vapor phase. Condensation may occur on cooled surfaces within the reaction chamber, in a separate condensation chamber, or in a condensation loop that circulates vapor through a cooled zone. The condensation temperature is selected to preferentially condense degradation products while maintaining the reactive chemical components in vapor form, or may be set to condense both degradation products and reactive chemicals for separation and reconditioning in downstream processing equipment.

[0096] In non-limiting examples, condensation surfaces may be maintained at temperatures ranging from 10°C to 20°C, 30°C. 40°C, 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, or within ranges such as 15°C to 160°C, 25°C to 150°C, 40°C to 130°C, 60°C to 120°C, or 80°C to 110°C depending on the volatilities of the species being separated. Lower condensation temperatures promote more complete condensation, but they require a greater cooling capacity-. Higher condensation temperatures reduce cooling requirements but may result in less complete separation. The condensed material drains or is removed from the condensation surfaces and collected in a condensate receiver. The condensate may undergo further processing including phase separation where immiscible phases are separated, fdtration to remove solids, distillation to separate components based on boiling points, or other purification techniques to separate degradation products from residual catalyst and solvent components that can be recycled.

[0097] Vapor reconditioning systems may include filtration to remove particulates, chemical treatment to restore catalyst activity or adjust pH, addition of fresh catalyst or swelling agent to compensate for consumed or depleted components, or complete replacement of degraded vapor with fresh reactive chemical solution. The reconditioning may occur continuously during processing with a side stream of vapor continuously withdrawn for treatment and returned, periodically at intervals such as every 15 minutes, every 30 minutes, every hour, every 2 hours, every 4 hours, or as determined based on vapor composition monitoring that detects when catalyst concentration or degradation product concentration reaches threshold values.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0098] In configurations employing continuous or semi-continuous vapor reconditioning, the vapor may be withdrawn from the reaction chamber, passed through a condensation stage where degradation products are removed, subjected to reconditioning where catalyst and swelling agent concentrations are adjusted to target values, revaporized in a vapor generator, and returned to the reaction chamber. The circulation rate may be selected to maintain vapor composition within target ranges, such as maintaining catalyst concentration within plus or minus 25%, plus or minus 20%, plus or minus 15%, plus or minus 10%, or plus or minus 5% of a target concentration value. This reconditioning loop transforms the batch process into a quasi-continuous process with respect to vapor quality', extending the effective processing capability without requiring shutdown for vapor replacement.

[0099] The chemical degradation of thermoset resins in the vapor phase environment proceeds through mechanisms involving catalyst-assisted bond cleavage that differ fundamentally from thermal pyrolysis mechanisms. For epoxy resins cured with amine hardeners, the degradation may involve cleavage of carbon-nitrogen bonds, carbon-oxy gen bonds, or both. The metal cation catalysts function as Lewis acids that coordinate with heteroatoms in the resin network, activating adjacent bonds for nucleophilic attack, hydrolysis, or other cleavage reactions. The polymer swelling component facilitates access of reactive species to interior portions of the crosslinked network by swelling the network and increasing free volume, allowing the catalyst to reach otherwise inaccessible crosslink sites.

[0100] The degradation proceeds from outer surfaces inward, with progressive breakdown of the crosslinked network into smaller oligomers and eventually into monomers or small molecular weight species. The aromatic structures present in many epoxy resins, such as the bisphenol A moieties in DGEBA-based epoxies, may be preserved during the degradation, or may undergo modification depending on the catalyst and processing conditions. The preservation of aromatic structures in the degradation products may facilitate subsequent recycling or valorization of the degraded resin material, as aromatic compounds often have value as chemical intermediates or can be repolymerized into new resins.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0101] For epoxy -anhydride systems where anhydride curing agents have been used instead of amine curing agents, the degradation may involve ester bond hydrolysis, opening of crosslinked structures through cleavage of ester linkages, and release of anhydride-derived carboxylic acid species. Polyurethane thermosets may undergo degradation of urethane linkages through hydrolysis or aminolysis reactions, potentially releasing polyols, isocyanate-derived products such as amines or ureas, or related species. The degradation pathway and products depend on the resin chemistry, the catalyst type and concentration, the presence of water or other reactants in the vapor phase, and the processing temperature and time.

[0102] The avoidance of thermal degradation represents an aspect of the vapor phase recycling processes and distinguishes chemical degradation from pyrolytic recycling approaches. Thermal degradation or pyrolysis of thermoset resins typically produces char (carbonized residue) which is difficult to remove from fiber surfaces and which may bond strongly to the fibers through chemical reactions between partially degraded resin and fiber surface groups. The presence of char on recovered fibers substantially degrades fiber quality, reduces fiber strength, and limits reuse potential. By maintaining temperatures below pyrolysis thresholds and relying on chemical rather than thermal degradation mechanisms, the production of char is minimized or substantially eliminated. The recovered fibers exhibit clean surfaces substantially free from adhered char or strongly bonded degradation products, as evidenced by visual inspection showing exposed fiber surfaces with minimal discoloration or residue.

[0103] The fibers recovered through the vapor phase recycling processes exhibit characteristics that can provide high-value reuse applications, distinguishing the vapor phase approach from mechanical or pyrolytic recycling methods that substantially degrade fiber quality or length. The preservation of fiber length represents an advantage, with continuous carbon fiber strands recovered in lengths substantially matching their original wound lengths.Recovered continuous strands may have lengths of at least 25 millimeters, at least 50 mm, at least 100 mm, at least 250 mm, at least 500 mm, at least 1 meter, at least 2 meters, at least 5 meters, at least 10 meters, at least 25 meters, at least 50 meters, at least 100 meters, at least 150 meters, at least 200 meters, at leastAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT500meters, at least 1 kilometer, at least 2 kilometers, at least 5 kilometers, at least 10 kilometers, or lengths ranging from 25 mm to 10 kilometers, 25 mm to 200 meters, 100 mm to 150 meters, 1 meter to 100 meters, 10 meters to 100 meters, 25 meters to 75 meters, or 40 meters to 60 meters.

[0104] The recovered fiber lengths may represent at least 25%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 99%, or substantially 100% of the original fiber length as wound in the component prior to recycling. Alternatively, the recovered fiber lengths may fall within closed ranges such as 25% to 100%, 50% to 100%, 70% to 100%, 80% to 99%, 85% to 98%, 90% to 97%, or 95% to 99.5% of the original wound length. The high recovery of fiber length, which may approach 99% as demonstrated in the pressure vessel example, provides substantial value for reuse applications, as continuous fibers can be rewound onto new components, woven into fabrics, used in filament winding operations, or otherwise utilized in applications that benefit from or require long fiber lengths.

[0105] For fabric segments, the recovered fabric area may be, for example, at least 20 square centimeters, at least 50 cm2, at least 100 cm2, at least 200 cm2, at least 500 cm2, at least 1000 cm2, at least 2000 cm2, at least 5000 cm2, at least 1 square meter, at least 2 m2, at least 5 m2, at least 10 m2, at least 20 m2, or fall within ranges such as 20 cm2to 20 m2, 100 cm2to 10 m2, 1000 cm2to 5 m2, 2000 cm2to 2 m2, or 5000 cm2to 1 m2The recovered fabric area may represent, for example, at least 25%, at least 50%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% of the original fabric area in the component, or may fall within closed ranges such as 25% to 100%, 50% to 100%, 70% to 99%, 80% to 97%, or 85% to 95% of the original area. Large intact fabric segments are valuable for applications such as composite repair patches, secondary composite fabrication, or reweaving into new fabric architectures.

[0106] The mechanical properties of the recovered fibers, such as tensile strength and modulus, are factors determining reuse value and application suitability. The vapor phase recycling processes result in fibers that retain substantial fractions of their original strength. Recovered fibers may exhibitAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTtensile strengths that are, for example, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%. at least 95%. or at least 97% of the tensile strength of comparable virgin fibers of the same type and grade.

[0107] Expressed in different terms, the strength retention may fall within ranges of 50% to 100%, 60% to 100%, 70% to 100%, 75% to 100%, 80% to 100%, 85% to 100%, 70% to 98%, 75% to 95%, 80% to 95%, 82% to 92%, 83% to 90%, or 85% to 95% of virgin fiber strength. For carbon fibers having original tensile strengths in the range of 3000 MPa to 6000 MPa, such as the AS4C carbon fiber which has a tensile strength around 4400 MPa, the recovered fibers may exhibit tensile strengths of at least 1500 MPa, at least 2000 MPa, at least 2500 MPa, at least 3000 MPa, at least 3500 MPa. at least 4000 MPa. at least 4500 MPa, or at least 5000 MPa, or may fall within closed ranges such as 2000 MPa to 5500 MPa, 2500 MPa to 5000 MPa, 3000 MPa to 4800 MPa, 3500 MPa to 4500 MPa, or 3700 MPa to 4200 MPa.

[0108] Where present, some strength reduction in recycling may result from surface damage to fibers during the recycling and handling processes. Fraying at fiber ends, abrasion during unwinding, contact with hard surfaces, or minor chemical effects at fiber surfaces may introduce surface flaws that reduce tensile strength. The vapor phase processing, however, is configured to minimize such mechanical damage compared to more aggressive liquid phase processing where component movement through liquid or liquid flow over components can cause fiber disruption, or mechanical processing methods that involve cutting, grinding, or other destructive size reduction. The maintenance of high fiber strength enables reuse in demanding structural applications including pressure vessels, aerospace components, automotive structures, or wind turbine blades where fiber mechanical performance is important.

[0109] The surface cleanliness of recovered fibers represents another quality factor influencing reusability of recycled product. Fibers recovered through the vapor phase processes exhibit substantially clean surfaces with minimal residual resin, degradation products, or char.

[0110] Following the vapor phase resin degradation treatment in the reaction chamber headspace, the components bearing stripped or substantially stripped fibers may be subjected to washing or cleaning processes to removeAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTresidual reactive chemicals and any remaining degradation product residues. The washing solution comprises highly polarized solvents that effectively dissolve and remove ionic species such as catalyst salts and polar degradation products that may adhere to fiber surfaces or remain trapped within fiber bundles.

[0111] Water is a suitable washing solvent due to its high polarity, availability, low cost, environmental compatibility, and effectiveness in dissolving aqueous catalyst solutions. The water may be ambient temperature water at about 20°C to 25°C, warm water at temperatures ranging from 30°C to 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or hot water approaching 100°C. Higher washing temperatures generally improve dissolution and removal kinetics but require heating systems and may pose handling challenges. In certain configurations, deionized water or distilled water may be employed to avoid introducing mineral contaminants that could deposit on fiber surfaces.Alternative or supplementary solvents include acetone, which provides good solvency for organic residues and evaporates rapidly facilitating drying; alcohols such as methanol, ethanol, isopropanol, or butanol which offer intermediate polarity; dimethylformamide which dissolves a broad range of organic materials; or combinations of these solvents that leverage complementary solvation properties.

[0112] The washing process may include immersion of the component in a washing bath where the component is placed in a tank or vessel containing washing solution, spraying of washing solution onto component surfaces using spray nozzles or atomizers, flowing washing solution over or through the component in a cascading or flooding arrangement, or combinations of these approaches. For wound fiber components, the washing solution may be allowed to wick or flow through the fiber layers by capillary action and gravity, dissolving and removing residual contaminants from between fibers and within fiber bundles. Gentle agitation such as rocking or vibration, rotation of the component on a rotatable support, or circulation of the washing solution using pumps may enhance washing effectiveness by promoting convective mass transfer and preventing concentration boundary layer buildup at fiber surfaces.

[0113] In some examples, multiple washing stages may be employed, such as an initial wash with a first solvent followed by one or more rinses with aAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTsecond solvent or with the same solvent refreshed between stages. For example, an initial wash with warm water may be followed by a rinse with room temperature water, reducing chemical and energy costs for the rinse stage. An initial wash with an organic solvent such as acetone may be followed by a water rinse, leveraging the strong solvency of acetone for organic residues followed by water's effectiveness in removing residual ionic species. In non-limiting examples, the washing time for each stage may range from 30 seconds to 1 minute, 2 minutes, 5 minutes, 10 minutes, 15 minutes, 30 minutes, 1 hour, 2 hours, 5 hours, 10 hours, or longer durations such as 24 hours for thorough cleaning, with appropriate selection based on component size, resin type, and washing solution effectiveness.

[0114] In some examples, the washing solution may be monitored for contaminant concentration using analytical techniques that provide feedback on washing effectiveness. Conductivity7measurements track ionic contaminant levels, with decreasing conductivity indicating removal of catalyst salts and other ionic species. pH measurements detect changes associated with removal of acidic swelling agents or basic degradation products. Spectroscopic analysis including UV -visible spectroscopy or fluorescence spectroscopy may detect aromatic degradation products. When contaminant concentrations drop below threshold values, the washing may be deemed complete. The washing solution itself may be subjected to filtration, ion exchange, reverse osmosis, or other treatment to remove contaminants and enable reuse of the w ashing solution for subsequent batches, improving process economics and reducing waste generation.

[0115] For components including wound carbon fiber strands, which include pressure vessels, overwrapped tubes, and similar wound structures, the fiber separation and collection process involves unwinding the strands from the component base structure such as a liner, mandrel, or other substrate. The gentle resin removal achieved through vapor headspace processing leaves the fibers in a condition where they can be readily unwound without excessive friction or binding that w ould occur if significant resin remained. The unwinding may be performed manually by an operator who identifies a fiber end by visual inspection or probing, grasps it using fingers or tools such as tweezers or pliers.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTand pulls to initiate unwinding. The initial fiber end identification may be facilitated by the exposed fiber appearance after resin removal. Alternatively, robotic or automated systems may identify fiber ends using machine vision systems that analyze component images to locate fiber terminations, grasp the end using grippers, suction cups, or other end effectors, and execute programmed unwinding routines that control unwinding speed and tension.

[0116] The component may be mounted on a rotating support that allows free rotation as the fiber is unwound, preventing twisting of the fiber and reducing unwinding forces. The support may comprise a mandrel inserted into the component interior, a pair of rollers supporting the component at its ends, a rotatable shaft, or other mechanism that permits low-friction rotation about the component's longitudinal axis. Bearing systems including ball bearings, roller bearings, or plain bearings with appropriate lubrication may be employed to minimize rotational resistance. In certain configurations, the rotational speed of the component support may be actively controlled using a motor or brake to maintain desired tension in the unwinding fiber, with speed control providing a means to regulate tension without directly contacting the fiber.

[0117] As the fiber is unwound, it may pass through guide rollers, tubes, eyelets, or other guiding elements that direct the fiber path and maintain alignment toward the winding station. The fiber may pass through a rinse bath containing water or other rinse liquid to perform final removal of residual contaminants. In non-limiting examples, the rinse bath may contain room temperature rinse liquid at about 20°C to 25°C, or the temperature may be controlled to values such as 15°C to 25°C, 20°C to 30°C, 25°C to 40°C. 30°C to 50°C, 40°C to 60°C, 50°C to 70°C, or 60°C to 80°C. The fiber transit time through the rinse bath, determined by bath length and fiber travel speed, may range from 1 second to 5 seconds, 10 seconds, 20 seconds, 30 seconds, 1 minute, 2 minutes, or longer durations depending on the bath length and unwinding speed, with longer residence times providing more complete rinsing. In some implementations rinse time in the bath may be less than 1 second.

[0118] Within the rinse bath, the fiber may pass over, under, or around one or more immersed rollers that ensure adequate contact time with the rinse liquid and prevent the fiber from simply bridging across the liquid surfaceAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTwithout submersion. A crowned roller configuration, wherein three or more rollers are arranged to direct the fiber path in a serpentine pattern ensuring submersion through multiple passes in the liquid, may be effective in providing thorough rinsing. The rollers may be smooth surfaced to avoid abrading the fiber, or may have controlled surface textures or coatings that provide cleaning action without damage. Roller materials may include stainless steel, ceramic, or polymer coatings selected for corrosion resistance and fiber compatibility.

[0119] After exiting the rinse bath, the fiber may pass through a moisture reduction system to remove excess liquid that would otherwise be carried to the winding station and potentially affect winding quality. The moisture reduction system may comprise a nip roller pair wherein two rollers pressed together with controlled force squeeze liquid from the fiber surface as the fiber passes between the rollers in the nip region. In non-limiting examples, the nip force may range from 1 Newton to 5 N, 10 N, 20 N, 30 N, 50 N, 100 N, 150 N, 200 N, 300 N, or fall within ranges such as 5 N to 300 N, 10 N to 200 N, 20 N to 150 N, 30 N to 100 N, or 40 N to 80 N. The nip roller surfaces may be compliant such as rubber, polyurethane, silicone, or elastomeric materials to distribute pressure and avoid fiber damage.

[0120] Alternative or supplementary moisture reduction may be achieved using air knives that direct high-velocity streams of air across the fiber surface to blow off liquid droplets, vacuum systems that draw liquid from the fiber through aspiration, heated zones that promote evaporation of residual moisture, or desiccant materials such as silica gel, molecular sieves, or calcium chloride that absorb moisture from air surrounding the fiber

[0121] The dried fiber may then be wound onto a collection spool, tube, or holder for storage and subsequent use, completing the fiber recovery process. In non-limiting examples, the collection spool may include a cardboard tube similar to those used for virgin fiber, a plastic spool made from materials such as polypropylene or ABS, a metal core made from aluminum or steel, or other suitable support structure providing dimensional stability and adequate strength.

[0122] The wound fiber on the collection spool may be wrapped with a protective film such as polyethylene film, placed in a sealed container such as a plastic bag or rigid container, or stored in a controlled environment to protectAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTagainst moisture absorption, contamination, or physical damage during storage before reuse.

[0123] For components comprising carbon fiber fabric segments, which are common in wind turbine blades, automotive body panels, and certain aerospace structures, the separation and collection process differs from wound strand processing due to the two-dimensional nature of fabrics and their typical layup configurations. Fabric segments typically lack a defined start and end point amenable to simple unwinding. Instead, the fabric is separated from the underlying substrate and removed as intact sheets or segments, preserving the fabric architecture and weave pattern.

[0124] Identification of fabric boundaries, edges accessible for grasping, and optimal removal sequences may be performed through examination of the component after vapor phase resin removal. If the component geometry7and fabric layup are known from design documentation or manufacturing records, this information guides the removal process by indicating where fabric edges or seams are located and which layers should be removed first to avoid damaging underlying layers. In cases where such information is unavailable, visual inspection by operators, manual probing using tools to locate fabric edges, or machine vision systems with image processing algorithms may identify fabric edges and separation points based on texture differences, color differences, or geometric features visible on the component surface.

[0125] Grasping of fabric edges may be performed manually by an operator using hands or tools such as pliers, clamps, or specialized fabric grippers, or may be performed robotically using automated grippers, suction devices that adhere to fabric surfaces through vacuum, magnetic grippers for fabrics with ferromagnetic fibers, or other end effectors suitable for fabric handling. Once grasped, the fabric is peeled or lifted away from the substrate, taking care to avoid tearing or fragmenting the fabric which would reduce the recovered fabric segment size. The peeling force and speed are controlled to balance efficient removal with fabric integrity preservation. In non-limiting examples, peeling forces may range from 0.05 New tons per centimeter of edge width to 0.1 N / cm, 0.5 N / cm, 1 N / cm, 2 N / cm, 5 N / cm, 10 N / cm, 20 N / cm, or fall within ranges such as 0.1 N / cm to 20 N / cm, 0.5 N / cm to 10 N / cm, 1 N / cm toAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT5 N / cm, or 2 N / cm to 4 N / cm.

[0126] For components with multiple fabric layers stacked one upon another, which is common in composite laminates, the layers may be removed sequentially starting from the outermost layer and proceeding inward toward the substrate, or alternative removal sequences such as removing larger or more accessible layers first may be employed based on the component configuration and layer accessibility. Separator sheets may be placed between removed fabric layers during stacking to prevent adhesion between layers and facilitate subsequent handling. The separator sheets may comprise paper such as kraft paper or tissue paper, polymer films such as polyethylene or polypropylene films, non-woven fabrics, release-coated materials such as silicone-coated papers, or perforated sheets that allow some air circulation during storage.

[0127] Removed fabric segments may be laid flat on collection surfaces such as tables or pallets, rolled onto cores or tubes for compact storage, or folded in accordion or other patterns for storage. For rolling, the fabric may be rolled with separator layers interleaved to prevent layer-to-layer contact and potential adhesion. The rolling tension is controlled to avoid creasing, permanent deformation, or damage.

[0128] Flat storage of fabric segments may involve stacking on shelves, hanging on racks using clips or clamps, or placement in drawers or bins.Identification labels or markers may be attached to indicate fabric type, weave pattern, areal weight, size, original component source, or other relevant information that assists in subsequent fabric selection for reuse applications. The storage environment may be controlled for temperature, humidity, and cleanliness as described for strand storage, protecting the fabric from environmental degradation or contamination.

[0129] In certain examples, the recovered fibers may be directly applied to new components without intermediate storage on spools or as fabric segments, providing a streamlined recycling and reuse process. This direct reuse approach reduces handling steps and associated potential for fiber damage or contamination. As continuous strands are unwound from a recycled component, they may be immediately wound onto a new component liner or mandrel, optionally with application of a fresh resin binder that will subsequently be curedAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTto form a new composite component.

[0130] The direct reuse configuration may include an unwinding station processing the recycled component and a winding station simultaneously winding fiber onto a new component, with the fiber path connecting the two stations and passing through rinse and dry ing stages as described previously. Tension control systems maintain appropriate tension throughout the fiber path from unwinding through rinsing, drying, and rewinding. Speed synchronization helps ensure the unwinding rate matches the winding rate, avoiding fiber slack that could lead to tangling or excessive tension that could cause fiber breakage or excessive stress.

[0131] For direct reuse with resin application, a resin bath or resin applicator may be positioned in the fiber path betw een the unwinding and winding stations, adding resin to the cleaned dry fiber. The fiber passes through liquid resin in a bath with controlled resin viscosity' and temperature, or resin is applied by spray application using atomizing nozzles, roller coating using metering rollers, or other application methods such as slot die coating or curtain coating. Excess resin may be removed by doctor blades that control w et film thickness, nip rollers that squeeze out excess resin, or air w iping using air knives. The resin-wetted fiber is then wound onto the new component following a winding pattern appropriate for the component application, and the component is subsequently cured according to the resin manufacturer's recommendations or optimized curing schedules.

[0132] In some examples, prior to introduction into the reaction chamber for vapor headspace processing, composite components may undergo various preparation steps that facilitate subsequent processing. Large components may be sectioned into smaller pieces to fit within available reaction chamber dimensions, though the vapor phase processing capability7for large intact components represents an advantage that may eliminate or minimize sectioning requirements. The ability to process a complete pressure vessel, large blade section, or other substantial component without cutting preserves the continuity of fibers and maximizes recovered fiber length. When sectioning is performed, cutting methods that minimize dust generation, fiber damage, and cutting forces may be employed, such as waterjet cutting that uses high-pressure water streamsAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTto cut through the composite, abrasive cutting using wheels or wires with coolant to manage heat, or precision sawing using diamond or carbide blades with low cutting speeds.

[0133] Components may be cleaned of gross contamination such as dirt, oil, grease, paint, or other foreign material using preliminary washing, wiping, brushing, or blasting techniques. Aqueous detergent solutions, organic solvents, or high-pressure water may remove surface contamination. This preliminary cleaning, while not removing the thermoset resin matrix, improves the effectiveness of subsequent vapor phase processing by eliminating contaminants that might interfere with vapor-resin interactions or that might contaminate recovered fibers. Metallic bosses, fittings, valves, sensors, or other removable non-composite components may be detached prior to processing using appropriate tools, or may remain attached if they do not interfere with the recycling process and can withstand the processing environment without degradation or contamination.

[0134] In some examples, liners in pressure vessels, which typically comprise aluminum, steel, or polymer materials, may remain in place during processing, serving as the support structure from which fibers are ultimately unwound. The liner material's resistance to the reactive vapor environment is considered, with metallic liners generally exhibiting good resistance, while polymer liners are selected from materials that do not degrade significantly under the processing conditions or are removed before processing if incompatible. Pre-treatment of components prior to vapor phase processing may, in certain configurations, include partial mechanical removal of resin from accessible surfaces using grinding, sanding, or scraping to expose fiber ends or reduce total resin content, scoring or abrading of resin surfaces to increase surface area and facilitate vapor penetration into the resin matrix, or application of surfactants or wetting agents that enhance liquid or vapor wetting of resin surfaces to improve initial vapor-resin contact.

[0135] In some examples, the orientation of components within the reaction chamber may be selected to optimize vapor exposure and drainage of condensate. Vertical orientation with the component long axis vertical, horizontal orientation with the component long axis horizontal, angledAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTorientation at various angles such as 30 degrees, 45 degrees, or 60 degrees from horizontal, or complex orientations may be employed depending on component geometry, size, and drainage requirements. Multiple components may be processed simultaneously in a single reaction chamber, with spacing between components sufficient to allow vapor circulation around all component surfaces. In non-limiting examples, inter-component spacing may range from 1 centimeter to 2 cm, 5 cm, 10 cm, 20 cm, 50 cm, or more, with greater spacing generally improving vapor circulation at the cost of reduced chamber utilization. Loading racks or fixtures may be designed to hold multiple components in configurations that maximize chamber utilization while ensuring adequate vapor access to the components positioned in the headspace above the liquid reservoir.

[0136] The positioning of composite components in the vapor headspace above a liquid reservoir of reactive chemical solution, rather than immersing the components in the liquid, provides several non-limiting advantages relative to conventional liquid-based solvolysis recycling. Components processed in the vapor headspace exhibited cleaner and more uniform fiber surfaces compared to components processed via liquid immersion using the same or similar chemical compositions. The fibers showed reduced entanglement, less mechanical disruption, and superior overall quality as evidenced by visual inspection and mechanical testing.

[0137] Moreover, the vapor environment in the headspace provides gentler conditions for the fibers as they are progressively exposed during resin removal. Without the mechanical forces associated with liquid flow around the component, liquid movement caused by component insertion or removal, or buoyancy effects that may shift or stress fibers, the fibers remain in their original positions and orientations with minimal disturbance. This gentle processing is particularly beneficial for maintaining the integrity of continuous fiber strands in wound configurations and large fabric segments in layup configurations, where any mechanical disturbance can cause fibers to shift, cross over each other, or become entangled in ways that complicate subsequent separation and collection.

[0138] Additionally, the headspace processing also allows handling of large components that might be difficult to fully immerse in liquid volumes that would be practically or economically challenging to contain. A relatively smallAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTvolume of liquid can generate sufficient vapor to fill a large headspace volume and process large components effectively.

[0139] Additionally, the vapor in the headspace can more readily access complex component geometries, internal passages, textured surfaces, and tightly packed fiber regions compared to liquid which may face flow restrictions, may not fully wet all surfaces due to surface tension effects, or may trap air pockets that prevent liquid contact. The vapor penetrates into all accessible regions of the component with equal facility regardless of geometry, providing uniform resin degradation across the entire component surface area. The vapor can penetrate between tightly wound fiber layers, between fabric plies in laminates, and into comers or recesses that would be difficult to access with liquid immersion.

[0140] The vapor phase recycling process may be monitored using various sensors and analytical techniques that provide data on process conditions, degradation progress, and completion status, enabling both quality control and process optimization. Temperature sensors such as thermocouples, resistance temperature detectors (RTDs), thermistors, or infrared sensors may be positioned at multiple locations within the reaction chamber to monitor temperature uniformity7and help ensure all regions remain within target temperature ranges. Sensor locations may include the liquid reservoir, the headspace vapor zone, the chamber walls, near the component surfaces, and at inlet or outlet ports.

[0141] Pressure sensors can monitor chamber pressure and provide data to pressure control systems that adjust heating, cooling, or pressure relief to maintain target pressure values or ranges. Pressure transducers using strain gauge, capacitive, piezoelectric, or other sensing technologies may be employed with measurement ranges and accuracies appropriate for the operating pressure range.

[0142] Optical sensors may monitor component appearance changes as resin is removed and fiber becomes exposed, providing a direct visual indicator of process progress. Camera systems with visible, near-infrared, or ultraviolet illumination may capture still images or video at periodic intervals. Image analysis algorithms implemented in software may quantify changes in surface reflectivity measured through grayscale values or intensity measurements, colorAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTmeasured through RGB or other color space analysis, or texture measured through spatial frequency analysis or edge detection. These quantitative metrics can correlate with resin removal progress, with increasing fiber exposure causing decreased reflectivity, color shifts toward the dark appearance of carbon fiber, and texture changes reflecting the fibrous surface structure. When predetermined image characteristics are achieved, such as reflectivity dropping below a threshold value or texture metrics exceeding a threshold indicating visible fiber texture, the process may be deemed complete.

[0143] Vapor composition monitoring may be performed using in-situ sensors positioned within the vapor headspace or by extracting small vapor samples through sampling ports for analysis in external instruments. Gas chromatography separates vapor components based on their interaction with a stationary7phase and detector responses, allowing identification and quantification of individual species. Mass spectrometry7provides molecular weight and structural information about vapor components, enabling identification of degradation products and tracking their concentration over time. Infrared spectroscopy detects functional groups based on vibrational absorption bands, allowing real-time monitoring of species such as acetate, epoxy-derived aromatics, or amine-derived compounds. These analytical techniques identify and quantify vapor components, allowing determination of degradation kinetics and prediction of completion times. Monitoring of degradation product concentrations shows initially low concentrations that increase as resin degradation begins, peak during active degradation, and then decline as resin removal nears completion. Detection of diminishing degradation product generation rates may indicate approaching completion of resin removal, triggering process termination or transition to a final polishing stage.

[0144] In some implementations, reaction chambers may be fitted with additional processing components, such as robotic manipulators, unwinding and winding components and functionality, pick and place capability7, cameras or windows for optical examination and / or characterization that may allow for gripping, extraction, winding or stacking of resin-free fiber portions while other portions of the carbon fiber continue to undergo resin removal. Such that preliminary removal of upper layers of carbon fiber may allow reactive vapor toAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTaccess what would otherwise be deeper, buried, and effectively otherwise inaccessible fiber regions particularly when original composite thickness was particularly large such as > 12 mm, > 24 mm, > 36 mm. After completion of in situ fiber separation and removal of the component and fiber from the reaction chamber, initially w ound and placed fiber may undergo unwinding or separation from a preliminary roll or stack, undergo additional cleaning, rinsing, examination, and then final characterization, winding or stacking for subsequent use or otherwise be put to immediate use.An Example:

[0145] Various aspects of the present disclosure can be better understood by reference to the following Examples, which are offered by way of illustration. The present disclosure is not limited to the Examples given herein.

[0146] The Composite Overw rapped Pressure Vessel (COPV) used in this example included an aluminum shell with an approximate diameter of 120 mm and an overall length of 230 mm. The shell was mounted on an X-Winder 4x-23 four-axis filament winding machine (X-Winder LLC, Northern New Mexico, USA), which w as equipped with a roll of Hexcel AS4C-12K carbon fibers. The X-Winder resin bath used about 150 g of resin mixture, comprising 115.5 g of Epon 826 (Hexion, Columbus, OH, USA) epoxy resin and 34.5 g of Jeffamine T-403 (Huntsman Performance Products, The Woodlands, TX, USA) curing agent.

[0147] Carbon fiber tow s were routed through the resin bath, which incorporated a custom bracket fitted with a tension monitor to ensure consistent tow tension around 8 N. The fibers were impregnated with the epoxy resin, and excess resin was removed using nip rollers. The pre-wetted tows were then guided through the delivery head onto the vessel. A custom G-code, generated using the X-Winder Designer software (X-Winder LLC, Northern New Mexico, USA), directed the winding process to alternate between four layers of hoop and helical winding.

[0148] During the helical winding phase, the filament was applied at an angle of 35 degrees for several passes until there was complete coverage of the aluminum vessel. This was follow ed by a transition to hoop winding for the cylindrical section of the vessel, with process parameters fine-tuned to account for the fiber tow width. Only four layers were applied to demonstrate the feasibility ofAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTrecycling carbon fiber composite pressure vessels while adhering to the physical limitations of the process; additional layers would have exceeded the capacity of the autoclave used for recycling. A fully operational pressure vessel designed for high-pressure applications would typically contain additional carbon fiber layers. After the winding process, the resin-wetted vessel w as removed from the X-Winder mandrel and cured in a convection oven at 150°C for 2 hours. FIG. 1 provides a schematic depiction of a winding apparatus similar to that used in composite overwrapped pressure vessel while FIG, 2 provide a photograph of the vessel formed.RESULTSChemical Recycling StepsMaterial / Vessel

[0149] The chemical recycling process employed an aqueous solution comprising 70% water, 20% zinc acetate, and 10% acetic acid. The recycling procedure involved placing 1 L of this solution into an autoclave, followed by sealing the vessel with the cured composite tank suspended above the liquid. The system w as heated to 240°C for 5 hours to depolymerize the epoxy resin matrix. Upon completion, the autoclave was allowed to cool, and the treated composite tank was carefully removed.

[0150] FIG. 3 provides a schematic representation of a reaction chamber similar to that used in the process of separating the resin from the Vessel of FIG.2, The schematic illustration of FIG. 3 includes a carbon fiber hardened resin composite structure located in the reaction chamber (e.g. an autoclave). FIG. 3 identifies various required and optional elements of a reaction chamber according to various aspects of the invention.

[0151] Visual inspection of the treated composite tank revealed that the fibers retained their wound orientation and exhibited significant removal of the epoxy resin, as evidenced by the diminished surface sheen and the predominance of exposed fibers Minimal fiber fraying was observed, and the end of the continuous fiber tow on the COPV w as located with relative ease.

[0152] FIG. 4 provides a photograph of the vessel after treatment in the reaction chamber.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0153] After vessel formation of FIGS. 1 and 2, and epoxy removal of FIGS. 3 and 4, the vessel with exposed carbon fiber was washed. FIG. 5 provides a schematic representation of a washing station that may receive a component that still includes carbon fiber wrapping or other fiber wrapping but which has already been stripped of encapsulating polymer using a reactive vapor solution that was applied in the process of FIGS. 1 and 2. Washing treatment removes any residual catalyst (e.g. zinc acetate), swelling agent (acetic acid) and any residual epoxy byproducts.

[0154] Next the cleaned carbon fiber is subject to unwinding from the original vessel liner and subsequent winding on a holding structure

[0155] The unwinding process was initiated by mounting the treated composite tank onto a custom-built unwinding apparatus, fabricated internally. Fibers were carefully unwound from the pressure vessel and subjected to an additional cleaning stage before being rewound onto a cardboard tube for storage and subsequent reuse.Unwinding / Cleaning Process

[0156] To demonstrate proper recycling and reclamation of the COPV postprocessing, a custom unwinding system / winding system was designed which included a strand cleaning station to remove any residual contaminates left on the surface of the fibers. A scehmatic diagram of the winder in shown FIG.5 which depicts the major elements involved and their functions. To begin the unwinding process, the recycled pressure vessel was placed onto a rod that allowed the vessel to spin with minimal resistance as the carbon fiber tow traveled through the cleaning and rewinding process. The tow was then directed by a smaller pair of guide rollers (not shown) into a container filled with room temperature w ater to w ash any contaminants in the fiber rinse bath. Within the bath, three rollers were placed in a crowned roller setup to ensure proper submersion and cleaning of the carbon fiber tow. During the cleaning process, there was visible discoloration to the water once the tow passed through the rollers, which indicated that the proper mechanical pressure w as being applied to the tow for cleaning w ithout excessive force, w hich may damage the fiber structure. Once the tow was cleaned in the water bath, a pair of nip rollers were placed before the final step of theAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTunwinding process to ensure the excess water and contaminants on the surface of the tow were removed before being wound onto a cardboard tube. FIG. 7 provides a photograph of the rewound, recycled carbon fiber taken from the vessel of FIGS. 2 and 4, using the system of FIG. 6.

[0157] The winder utilized during this process was the Seco Bronco DC drive (Superior Electric, Bristol. CT. USA), equipped with a variable-speed knob that provided precise control over the unwinding operation. This feature ensured that the tow was gently and consistently unwound from the recycled pressure vessel at a manageable speed, minimizing mechanical stress on the fibers. As a result, the newly collected spool of recycled fibers exhibited limited fraying and surface contamination. This process demonstrates an effective method for recycling high-performance carbon fiber materials from COPVs, addressing challenges related to thermoset composite recycling, minimizing waste, and contributing to a circular economy.Mechanical Properties

[0158] After unwinding the pressure vessel and rewinding the fibers onto the cardboard tube, samples of the recycled fiber tow were prepared for tensile testing. To prepare the tow, segments of recycled fiber were cut and suspended on a T-frame 50.8 cm tall. The fiber tows were then passed through a resin bath and fitted with a 2.38 mm shrink tube at the top of the T-frame. The top half of the shrink tube was heated to create a funnel for the fibers to pass through. Once the top half of the tube was shrunk, the shrink tube w as dragged along the length of the tow to remove excess resin and form the tow composite into a long cylinder. After removing the shrink tube, a 100 g weight was attached to the bottom of the tow- to maintain tension on the fibers during the curing process. After curing, the composite tows were placed in a mold to form epoxy end tabs, preventing damage during gripping in the test frame. The resulting length of the tow is about 140 mm, with a gauge length of 60 mm. Once the composite tows were cured and the epoxy end tabs were formed, the samples w ere subjected to tensile testing. The fiber tows were carefully mounted into the manually adjusted grips of the test frame, ensuring proper alignment to minimize potential sources of error during the test. Tensile testing was performed under controlled ambient conditions, with a crosshead speed of 2 mm / min.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0159] The mechanical properties of the carbon fiber tows from the recycled COPV were evaluated in comparison to a control tow made with pristine carbon fibers. Tensile results revealed a slight reduction in strength, with the recycled fiber tows from the outer layer of the COPV exhibiting about 332 MPa decrease in strength compared to the control w ith the results shown in FIG. 8. Part of the performance reduction observed in this study is due to fraying of the tank fibers during assembly, recycling, and handling, which likely resulted in the reduced mechanical properties but still demonstrates only a 15% drop in tow strength.CONCLUSIONS

[0160] This Example highlights the successful capture and reutilization opportunities of continuous carbon fiber tows from Composite Overwrapped Pressure Vessels (COPVs) through a sustainable, low-temperature chemical recycling process. The method demonstrated the feasibility' of recovering nearly 99% of the continuous fibers while maintaining most of their structural integrity, with about a 15% reduction in tensile strength compared to pristine fibers. This reduction is primarily attributed to fraying during the handling, assembly, and recycling phases.

[0161] The ability to effectively capture and reuse long- fonn, continuous, carbon fiber tows from COPVs is a significant step forward in advancing the circular economy for high-performance materials. This work demonstrates the potential for a closed- loop system in the hydrogen storage industry, where carbon fiber tows recovered from end-of- life COPVs can be reused in the manufacturing of new vessels and alternative material forms utilizing continuous fiber, minimizing waste and reducing the demand for virgin carbon fiber. Future research will focus on refining the recycling process to further enhance fiber quality' and mechanical performance, ensuring that recovered fibers can be seamlessly reintegrated into the production of high-strength, pressure-resistant composite materials for hydrogen storage.Another Example:

[0162] In another example, epoxy removal from carbon fiber fabric was evaluated based on an alternative reactive chemical solution. CFRP composites were formed as 8 ply composites with T300 carbon fiber with 60% carbon fiberAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTand 40% resin with the resin being EPON 826 (epoxy) + Jeffamine T403. (amine). Recycling was done using various concentrations of acetic acid and water. No separate catalyst or swelling agent was used. The acetic acid in water functioned as both a swelling agent and a catalyst temperature.Experimental Set Up

[0163] Solutions of acetic acid (~300-500mL) were made by mixing water and acetic acid and stirring at 300 rpm for 5 minutes. Experimental solutions included 80%, 20%, and 5% acetic acid with the remainder of each being water. Solutions were poured in an autoclave. A metal stand was placed in solution with a beaker on top. CFRP (weight was between 16g - 48g) which was placed in the beaker, not in contact with the solution. The autoclave was set to 240 °C (~30 min - Ihr) to heat up. Pressure reached about 400-500 psi at temperature. Reactions w ere allowed to occur at 240 °C for 6 hr - 18 hr. The autoclave was then turned off and left to cool down to room temperature. The autoclave was opened, the fibers were collected and then washed with water and acetone via ultrasonication (15 minutes in each solvent), followed by drying at room temperature overnight or 60C for a few' hours. The final dried fibers w ere weighed to determine resin degradation.RESULTSAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0164] Samples were weighed before and after the recycling reaction in the autoclave. Weight loss ranged from 48 - 52%. This does not take into account the weight fraction of carbon fiber and resin (this still need to be experimentally measured). However, based off the weight loss and images it is expected that the resin removal was between 95-100%.

[0165] Another experiment was performed with 20% citric acid and 80% water at 170 °C for 60 hours. The experiment did not result in sufficient epoxy removal.Conclusions:

[0166] Acetic acid at various concentrations in water can be used in a vapor phase to separate solidified epoxy resin from carbon fiber under appropriate temperature and pressure parameters.Exemplary7Aspects.

[0167] The following exemplary aspects are provided, the numbering of which is not to be construed as designating levels of importance:

[0168] Aspect 1 provides a method for recycling at least one continuous carbon fiber strand from at least one component wherein the at least one carbon fiber strand is embedded in solidified thermoset resin to obtain at least one carbon fiber strand for reuse as at least one continuous carbon fiber strand, the method comprising:Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTproviding a reaction chamber for removing solidified thermoset resin from the carbon fiber wherein the chamber is configured to hold a vapor solution at a specified reaction temperature and a specified reaction pressure, for a specified reaction duration, and wherein the chamber has at least one first location for holding at least one component and at least one location for receiving degraded resin reaction products;locating the at least one component to be recycled at the at least one first location of the reaction chamber;introducing a vaporized reactive chemical solution into the reaction chamber and maintaining the vapor at a specified reaction temperature, at a specified reaction pressure, and for a specified reaction duration to provide effective removal of the solidified thermoset resin to provide a component with at least one bare carbon fiber strand with the at least one bare carbon fiber strand remaining wound and in an undamaged state;wherein the chemical solution comprises:a catalyst solution comprising a catalyst dissolved in a solvent, anda polymer swelling material that is miscible with the catalyst solution;wherein the specified reaction temperature and specified pressure provide for chemical degradation of the solidified resin with the temperature and pressure holding the reactive chemical solution in a vaporized state around the component while also being appropriate to avoid causing thermal degradation of the solidified resin or its reaction products;optionally subjecting the at least one bare carbon fiber to a liquid washing solution to wash away residual reactive chemical solution; and unwinding the at least one bare carbon fiber strand from any remaining part of the at least one component and winding the at least one bare carbon fiber strand on to at least one holder to provide a held bare carbon fiber for subsequent use as at least one continuous carbon fiber strandwherein the catalyst and the swelling material may be the same material or different materials.

[0169] Aspect 2 provides the method of Aspect 1, wherein unwindingAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTthe at least one bare carbon fiber strand further comprises pulling the at least one strand of the bare carbon fiber to unwind it, then passing the at least one bare carbon fiber strand through a rinsing solution and then through a moisture reducer, and then winding the at least one bare carbon fiber strand on to the at least one holder.

[0170] Aspect 3 provides the method of Aspect 2, wherein the moisture reducer comprises a nip roller.

[0171] Aspect 4 provides the method of any of Aspects 2 or 3, wherein the moisture reducer comprises a heating element.

[0172] Aspect 5 provides the method of any of Aspects 2-4, wherein the moisture reducer comprises a desiccant.

[0173] Aspect 6 provides the method of any of Aspects 1-5, wherein the solidified thermoset resin comprises an epoxy.

[0174] Aspect 7 provides the method of any of Aspects 1-6, wherein the solidified thermoset resin comprises a polyurethane.

[0175] Aspect 8 provides the method of any of Aspects 1-7, wherein the reactive chemical solution comprises:30 wt.% to 90 wt.% catalyst solution; and10 wt.% to 70 wt.% polymer swelling component.

[0176] Aspect 9 provides the method of any of Aspects 1-8, wherein the catalyst solution comprises 10 wt.% to 50 wt.% catalyst and 50 wt.% to 90 wt.% solvent,wherein the catalyst comprises a material selected from the group consisting of:an anion and cation,wherein the cation is selected from the group consisting of Zn2+, Fe3+, Fe2+, Cu2, Cu+, Cr3+, Cr2+, Mn3+, Mn2+, Co3+, Ni2+, Ni3+, Sn2+, Sn4+, Pb2+, and Pb4+, andwherein the anion is selected from the group consisting of: acetate, formate, propionate, octoate, ethanedioate, an organic sulphonic acid ion,zinc chloride,aluminum chloride,Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTboron trifluoride,titanium tetrachloride,NaOCl,tripotassium phosphate,a weak organic acid,a weak organic acid including acetic acid (e.g. in glacial form), anda weak organic acid including formic acid (e.g. in anhydrous form),wherein the solvent comprises a material selected from the group consisting of a highly polarized solvent, water, glycerol, an alcohol, methanol, ethanol, dimethyl sulfoxide, and dimethylformamide.

[0177] Aspect 10 provides the method of Aspect 9, wherein the polymer swelling component comprises a material selected from the group consisting of a weak organic acid, acetic acid (e.g. in glacial form), citric acid, formic acid (e.g. in anhydrous form), HNOa, and a combination of at least two thereof.

[0178] Aspect 11 provides the method of Aspect 10, wherein the polymer swelling component comprises acetic acid, and the catalyst solution comprises water and zinc acetate.

[0179] Aspect 12 provides the method of Aspect 11 , wherein the acetic acid provides about 10 wt.% of the reactive chemical solution, water provides about 70 wt.% of the reactive chemical solution, and zinc acetate provides about 20 wt.% of the reactive chemical solution.

[0180] Aspect 13 provides the method of any of Aspects 1-12, wherein the specified reaction temperature is in a range selected from the group consisting of: 150°C to 300°C; 180°C to 250°C; and 180°C to 200°C.

[0181] Aspect 14 provides the method of any of Aspects 1-13, wherein the specified reaction pressure is in a range selected from the group consisting of: 400 psi to 1000 psi; 500 psi to 800 psi; and 500 psi to 600 psi.

[0182] Aspect 15 provides the method of any of Aspects 1-14, wherein the specified reaction duration is in a range selected from the group consisting of: 1 hour to 48 hours; 2 hours to 12 hours; and 4 hours to 8 hours.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0183] Aspect 16 provides the method of any of Aspects 1-15, wherein the specified reaction duration is set at least in part based on a detection indicating that sufficient resin removal has occurred.

[0184] Aspect 17 provides the method of Aspect 16, wherein the detection comprises use of at least one sensor.

[0185] Aspect 18 provides the method of any of Aspects 1-17, wherein the method additionally comprises reconditioning the reactive vaporized chemical solution to maintain the composition of the reactive vaporized chemical solution within a desired target range during the reaction duration.

[0186] Aspect 19 provides the method of Aspect 18, additionally comprising replenishing catalyst during the reaction duration.

[0187] Aspect 20 provides the method of any of Aspects 1-19, wherein the reactive vaporized chemical solution is flowed around the component during the reaction duration.

[0188] Aspect 21 provides the method of any of Aspects 1-20, wherein the reactive vaporized chemical solution undergoes condensation to collect and remove degraded resin to form a refreshed chemical solution which is followed by revaporization of the refreshed reactive chemical solution.

[0189] Aspect 22 provides the method of any of Aspects 1-21, wherein the liquid washing solution comprises a material that is a highly polarized washing solvent.

[0190] Aspect 23 provides the method of Aspect 22, wherein the highly polarized washing solvent is selected from the group consisting of: water, glycerol, an alcohol, methanol, ethanol, dimethyl sulfoxide, and dimethylformamide.

[0191] Aspect 24 provides the method of any of Aspects 22 or 23, wherein the highly polarized solvent comprises a solvent selected from the group consisting of: water, acetone, alcohol, and dimethylformamide.

[0192] Aspect 25 provides the method of any of Aspects 2-24, wherein the rinsing solution comprises a liquid selected from the group consisting of water, acetone, and alcohol.

[0193] Aspect 26 provides the method of Aspect 25, wherein during rinsing the at least one strand is moved relative to the rinsing solution.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0194] Aspect 27 provides the method of any of Aspects 1-26, wherein in addition to recycling at least one carbon fiber strand, the method also recycles at least a portion of the degraded solidified resin products for reuse.

[0195] Aspect 28 provides the method of Aspect 27, wherein a portion of the catalyst that gets captured by the degraded solidified resin products is reclaimed for reuse.

[0196] Aspect 29 provides the method of any of Aspects 1-28, wherein the component comprises a high pressure vessel.

[0197] Aspect 30 provides the method of any of Aspects 1-29, wherein the component comprises a high pressure tube or pipe.

[0198] Aspect 31 provides the method of any of Aspects 1-30, wherein the at least one held bare continuous carbon fiber strand has a strength selected from the group consisting of: at least 50% of that of a comparable newly fabricated strand, at least 70% of that of a comparable newly fabricated strand, at least 85% of that of a comparable newly fabricated strand; at least 90% of that of a comparable newly fabricated strand; and at least 95%of that of a comparable newly fabricated strand.

[0199] Aspect 32 provides the method of any of Aspects 1-31, wherein the at least one held bare continuous carbon fiber strand has a length that is selected from the group consisting of: at least 25 mm, at least 10 cm, at least 1 m, at least 10 m, at least 100 m, at least 25% of a length of the carbon fiber strand as wound prior to recycling, at least 50% of a length of the carbon fiber strand as wound prior to recycling, at least 80% of a length of the carbon fiber strand as wound prior to recycling, at least 90% of a length of the carbon fiber strand as wound prior to recycling, at least 95% of a length of the carbon fiber strand as wound prior to recycling, and at least 99% of a length of the carbon fiber strand as wound prior to recycling.

[0200] Aspect 33 provides the method of any of Aspects 1-32, wherein the at least one carbon fiber strand comprises a plurality of carbon fiber strands and the at least one bare carbon fiber strand comprises a plurality of bare carbon fiber strands.

[0201] Aspect 34 provides the method of any of Aspects 1-33, wherein acetic acid provides, at least in part, the polymer swelling component and theAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTcatalyst component.

[0202] Aspect 35 provides the method of Aspect 34 wherein the acetic acid provides at least a portion of the reactive chemical solution selected from the group consisting of: (A) at least 1%, (B) at least 3%, (C) at least 5%, (D) at least 10%, (E) at least 20%, (F) at least 40%, (G) at least 80%, (H) no more than 100%, (I) no more than 90%, (J) no more than 85%, and (K) no more than 80%.

[0203] Aspect 36 provides a method for recycling carbon fiber from a composite component, comprising:providing a component comprising carbon fiber embedded in solidified thermoset resin;exposing the component to a reactive vapor comprising a catalyst at an elevated temperature for a period of time sufficient to at least partially degrade the solidified thermoset resin; andseparating at least a portion of the carbon fiber from the component.Aspect 37 provides the method of Aspect 36, wherein the reactive vapor comprises a catalyst solution comprising a catalyst dissolved in a solvent and a polymer swelling material that is miscible with the catalyst solution.

[0204] Aspect 38 provides the method of Aspect 37, wherein the catalyst comprises at least one of a weak organic acid, acetic acid, formic acid, zinc chloride, aluminum chloride, boron trifluoride, titanium tetrachloride, NaOCl, tripotassium phosphate, or a metal cation selected from the group consisting of: Zn2+, Fe3+, Fe2+, Cu2+, Cu+, Cr3', Cr21, Mn31, Mn21, Co31, Ni2', Ni3+, Sn2+, Sn4+, Pb2+, and Pb4+.

[0205] Aspect 39 provides the method of any of Aspects 37 or 38, wherein the polymer swelling material comprises a material selected from the group consisting of: a weak organic acid, acetic acid, citric acid, formic acid, and HNCh.

[0206] Aspect 40 provides the method of any of Aspects 36-39, wherein the elevated temperature is maintained without causing thermal degradation of the solidified thermoset resin and the elevated temperature is in a range selected from the group consisting of: 150°C to 300°C; 180°C toAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT250°C; and 180°C to 200°C.

[0207] Aspect 41 provides the method of any of Aspects 36-41, wherein exposing the component occurs in a reaction chamber maintained at an elevated pressure.

[0208] Aspect 42 provides the method of Aspect 41, wherein the elevated pressure is in a range selected from the group consisting of: 400 psi to 1000 psi; 500 psi to 800 psi; and 500 psi to 600 psi.

[0209] Aspect 43 provides the method of any of Aspects 36-42, wherein the period of time is in a range selected from the group consisting of: 1 hour to 48 hours; 2 hours to 12 hours; and 4 hours to 8 hours.

[0210] Aspect 44 provides the method of any of Aspects 36-43, wherein the carbon fiber comprises at least one continuous carbon fiber strand that remains wound after separation.

[0211] Aspect 45 provides the method of Aspect 44, wherein the at least one continuous carbon fiber strand has a length selected from the group consisting of: at least 25 mm, at least 10 cm, at least 1 m, at least 10 m, and at least 100 m, at least 200m, at least 500 m, at least 1 km, at least 2 km, at least 5 km, and at least 10 km.

[0212] Aspect 46 provides the method of any of Aspects 36-45, wherein the carbon fiber comprises a carbon fiber fabric segment.

[0213] Aspect 47 provides the method of any of Aspects 36-46, further comprising subjecting the separated carbon fiber to a liquid washing solution comprising a highly polarized solvent selected from the group consisting of: water, glycerol, an alcohol, methanol, ethanol, dimethyl sulfoxide, acetone, and dimethylformamide.

[0214] Aspect 48 provides the method of any of Aspects 36-47, wherein the separated carbon fiber is wound onto a holder for storage.

[0215] Aspect 49 provides the method of any of Aspects 36-48, wherein the solidified thermoset resin comprises an epoxy or a polyurethane.

[0216] Aspect 50 provides the method of any of Aspects 36-49, wherein the reactive vapor comprises about 70 wt.% water, about 20 wt.% zinc acetate, and about 10 wt.% acetic acid.

[0217] Aspect 51 provides the method of any of Aspects 36-50,Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTwherein degraded resin reaction products are collected and recycled for reuse.

[0218] Aspect 52 provides the method of Aspect 51 , wherein the catalyst captured by the degraded resin products is reused.

[0219] Aspect 53 provides the method of any of Aspects 36-52, wherein the component comprises a pressure vessel, a pressure tube, a pipe, a wind turbine blade component, or an automotive component.

[0220] Aspect 54 provides the method of any of Aspects 36-53, wherein the reactive vapor is flowed around the component and undergoes condensation to collect degraded resin followed by revaporization.

[0221] Aspect 55 provides the method of any of Aspects 36-54, wherein the separated carbon fiber retains at least 70% of a tensile strength of virgin carbon fiber and has a length of at least 25% of an original fiber length in the component.

[0222] Aspect 56 provides the method of any of Aspects 36-54, wherein the method recovers at least 90% of the carbon fiber from the component.

[0223] Aspect 57 provides the method of any of Aspects 36-56, wherein the carbon fiber is passed through a moisture reducer comprising a nip roller, a heating element, or a desiccant after washing.

[0224] Aspect 58 provides the method of any of Aspects 36-57 wherein the catalyst comprises acetic acid which also provides for swelling.

[0225] Aspect 59 provides the method of Aspect 58 wherein the acetic acid provides at least a portion of the reactive chemical solution selected from the group consisting of (A) at least 1%, (B) at least 3%, (C) at least 5%, (D) at least 10%, (E) at least 20%, (F) at least 40%, (G) at least 80%, (H) no more than 100%, (I) no more than 90%, (J) no more than 85%, and (K) no more than 80%.

[0226] Aspect 60 provides a method for recovering fiber from a thermoset composite, comprising:contacting a thermoset composite component with a reactive vapor comprising a catalyst at a temperature above the vaporization temperature of the solution; andAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTmaintaining the temperature for a time sufficient to at least partially chemically degrade crosslinked resin in the thermoset composite to allow fiber recovery.

[0227] Aspect 61 provides the method of Aspect 60, wherein the fiber comprises carbon fiber or glass fiber.

[0228] Aspect 62 provides the method of any of Aspects 60 or 61, wherein the temperature is below a pyrolysis temperature of the crosslinked resin to substantially avoid char formation.

[0229] Aspect 63 provides the method of any of Aspects 60-62, wherein the vaporized catalyst- containing solution comprises an organic salt catalyst and a polymer swelling component.

[0230] Aspect 64 provides the method of Aspect 63, wherein the organic salt catalyst comprises zinc acetate and the polymer swelling component comprises acetic acid.

[0231] Aspect 65 provides the method of any of Aspects 60-64, wherein contacting occurs in a sealed chamber maintained at elevated pressure.

[0232] Aspect 66 provides the method of any of Aspects 60-65, further comprising recovering the fiber in a continuous form having a length of at least 1 meter.

[0233] Aspect 67 provides the method of any of Aspects 60-66, wherein the crosslinked resin comprises an epoxy resin or a polyurethane resin.

[0234] Aspect 68 provides the method of any of Aspects 60-67, wherein the thermoset composite component comprises filament wound fibers or fabric layers.

[0235] Aspect 69 provides the method of any of Aspects 60-68, further comprising washing the recovered fiber with a polar solvent selected from the group consisting of water, acetone, alcohol, and dimethylformamide.

[0236] Aspect 70 provides the method of any of Aspects 60-69, wherein degraded resin reaction products are collected, and catalyst is reclaimed for reuse.

[0237] Aspect 71 provides the method of any of Aspects 60-70,Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTwherein the component comprises a pressure vessel, wind turbine blade component, or automotive component.

[0238] Aspect 72 provides the method of any of Aspects 60-71, wherein the vaporized catalyst- containing solution is recirculated and reconditioned during the method.

[0239] Aspect 73 provides the method of any of Aspects 60-72, wherein the recovered fiber retains at least 85% of virgin fiber strength.

[0240] Aspect 74 provides the method of any of Aspects 60-73, wherein the method recovers at least 99% of the fiber from the component.

[0241] Aspect 75 provides the method of any of Aspects 60-74, wherein the time is determined based on sensor detection of resin removal.

[0242] Aspect 76 provides the method of any of Aspects 60-75, wherein the temperature is maintained in a range of 180°C to 250°C.

[0243] Aspect 77 provides the method of any of Aspects 60-76, wherein the vaporized catalyst- containing solution comprises water as a solvent and a metal cation catalyst.

[0244] Aspect 78 provides the method of any of Aspects 60-77, wherein the recovered fiber is wound onto a spool after passing through a moisture reducer.

[0245] Aspect 79 provides the method of any of Aspects 60-78, wherein the reactive vapor comprises 30 wt.% to 90 wt.% catalyst solution and 10 wt.% to 70 wt.% polymer swelling component.

[0246] Aspect 80 provides the method of any of Aspects 60-79, wherein the vaporized catalyst containing solution comprises at least one material that provides a catalytic function and a polymer swelling function.

[0247] Aspect 81 provides the method of Aspect 80, wherein the at least one material comprises a weak organic acid which provide both the catalytic function and the swelling function.

[0248] Aspect 82 provides the method of Aspect 81 , wherein the weak organic acid comprises at least one of acetic acid or formic acid.

[0249] Aspect 83 provides a system for recycling at least one continuous carbon fiber strand from at least one component wherein the at least one carbon fiber strand is at least partially embedded in solidifiedAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTthermoset resin to obtain at least one carbon fiber strand configured for reuse as at least one continuous carbon fiber strand, comprising:a reaction chamber for removing solidified thermoset resin from the carbon fiber wherein the chamber is configured to hold a vapor solution at a specified reaction temperature and a specified reaction pressure, for a specified reaction duration, and wherein the chamber has at least one first location for holding the at least one component and at least one location for receiving degraded resin reaction products;a reactive chemical solution configured to be introduced into the reaction chamber and configured while in a vaporized state to surround a component to be recycled and being maintained in the vaporized state at a specified reaction temperature, at a specified reaction pressure, and for a specified reaction duration to provide effective removal of solidified thermoset resin from the at least one carbon fiber strand to provide at least one bare carbon fiber strand with the at least one bare carbon fiber strand remaining wound and undamaged state;wherein the chemical solution comprises:a catalyst solution comprising a catalyst dissolved in a solvent, anda polymer swelling material that is miscible with the catalyst solution,wherein the specified reaction temperature and pressure provide for chemical degradation of the solidified resin, with the temperature and pressure holding the reactive chemical solution in a vaporized state around the at least one component while also being appropriate to avoid causing thermal degradation of the solidified resin or its reaction byproducts;optionally, a washing station for subjecting the at least one carbon fiber strand to a liquid washing solution to wash away residual reactive chemical solution; andan unwinding station for unwinding the at least one carbon strand from any remaining part of the at least one component and winding the at least one carbon fiber strand on to at least one spool for subsequent use as at least one continuous carbon fiber strand.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0250] Aspect 84 provides the system of Aspect 83, wherein the unwinding station further provides for pulling the at least one bare carbon fiber strand to unwind it, passing the at least one unwound bare carbon fiber strand through a rinsing solution and then through a moisture reducer, and then winding the at least one bare carbon fiber strand on to the at least one spool.

[0251] Aspect 85 provides the system of Aspect 84, wherein the moisture reducer comprises a nip roller.

[0252] Aspect 86 provides the system of Aspect 84, wherein the moisture reducer comprises a heating element.

[0253] Aspect 87 provides the system of Aspect 84, wherein the moisture reducer comprises a desiccant.

[0254] Aspect 88 provides the system of any of Aspects 83-87, wherein the solidified thermoset resin system comprises an epoxy.

[0255] Aspect 89 provides the system of any of Aspects 83-88, wherein the solidified thermoset resin system comprises a polyurethane.

[0256] Aspect 90 provides the system of any of Aspects 83-89, wherein the reactive chemical solution comprises:30 wt.% to 90 wt.% catalyst solution, and10 wt.% to 70 wt.% polymer swelling component.

[0257] Aspect 91 provides the system of any of Aspects 83-90, wherein the catalyst comprises a material selected from the group consisting of:an anion and cation,wherein the cation is selected from the group consisting of Zn2+, Fe3+, Fe2+, Cu2, Cu+, Cr3+, Cr2+, Mn3+, Mn2+, Co3+, Ni2+, Ni3+, Sn2+, Sn4+, Pb2+, and Pb4+, andwherein the anion is selected from the group consisting of: acetate, formate, propionate, octoate, ethanedioate, an organic sulphonic acid ion,zinc chloride,aluminum chloride,boron trifluoride,Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTtitanium tetrachloride,NaOCl,tripotassium phosphate,a weak organic acid ,a weak organic acid including acetic acid (e.g. in glacial form), a weak organic acid including formic acid (e.g. in anhydrous form); andwherein the solvent comprises a material selected from the group consisting of: a highly polarized solvent, water, glycerol, an alcohol, methanol, ethanol, dimethyl sulfoxide, and dimethylformamide.

[0258] Aspect 92 provides the system of Aspect 91, wherein the polymer swelling component comprises acetic acid, and the catalyst solution comprises water and zinc acetate.

[0259] Aspect 93 provides the system of Aspect 92, wherein the acetic acid provides about 10 wt.% of the reactive chemical solution, water provides about 70 wt.% of the reactive chemical solution, and zinc acetate provides about 20 wt.% of the reactive chemical solution.

[0260] Aspect 94 provides the system of any of Aspects 83-93, wherein the specified reaction temperature is in a range selected from the group consisting of: 150°C to 300°C; 180°C to 250°C; and 180°C to 200°C.

[0261] Aspect 95 provides the system of any of Aspects 83-94, wherein the specified reaction pressure is in a range selected from the group consisting of: 400 psi to 1000 psi; 500 psi to 800 psi; and 500 psi to 600 psi.

[0262] Aspect 96 provides the system of any of Aspects 83-95, wherein the specified reaction duration is in a range selected from the group consisting of: 1 hour to 48 hours; 2 hours to 12 hours; and 4 hours to 8 hours.

[0263] Aspect 97 provides the system of any of Aspects 83-96, wherein the specified reaction duration is set at least in part based on a detection indicating that sufficient resin removal has occurred.

[0264] Aspect 98 provides the system of Aspect 97, wherein the detection is provided by at least one sensor.

[0265] Aspect 99 provides the system of any of Aspects 83-98, wherein the system additionally comprises reconditioning the reactiveAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTvaporized chemical solution to maintain the composition of the reactive vaporized chemical solution within a desired target range during the reaction duration.

[0266] Aspect 100 provides the system of Aspect 99, additionally comprising replenishing catalyst during a specified reaction period.

[0267] Aspect 101 provides the system of any of Aspects 83-100, wherein the reactive vaporized chemical solution is flowed around the component during the reaction duration.

[0268] Aspect 102 provides the system of any of Aspects 83-101, wherein the reactive vaporized chemical solution undergoes condensation to collect and remove degraded resin to form a refreshed chemical solution which is followed by revaporization of the refreshed reactive chemical solution.

[0269] Aspect 103 provides the system of any of Aspects 83-102, wherein the liquid washing solution comprises a material that is a highly polarized solvent.

[0270] Aspect 104 provides the system of Aspect 103, wherein the highly polarized solvent comprises a solvent selected from the group consisting of: water, glycerol, an alcohol, methanol, ethanol, dimethyl sulfoxide, and dimethylformamide.

[0271] Aspect 105 provides the system of any of Aspects 103 or 104, wherein the highly polarized solvent comprises a solvent selected from the group consisting of: water, acetone, alcohol, and dimethylformamide.

[0272] Aspect 106 provides the system of any of Aspects 84-105, wherein the rinsing solution comprises a liquid selected from the group consisting of: water, acetone, and alcohol.

[0273] Aspect 107 provides the system of any of Aspects 84-106, wherein during rinsing the at least one strand is moved relative to the rinsing solution.

[0274] Aspect 108 provides the system of any of Aspects 83-107, wherein in addition to recycling at least one carbon fiber strand, the system also recycles the degraded solidified resin products for reuse.

[0275] Aspect 109 provides the system of Aspect 108, wherein catalystAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTcaptured by the degraded solidified resin products is recliamed for reuse.

[0276] Aspect 110 provides the system of any of Aspects 83-109, wherein the system is configured to handle a component comprising a high pressure vessel.

[0277] Aspect 111 provides the system of any of Aspects 83-110, wherein the system is configured to handle a component comprising a high pressure tube or pipe.

[0278] Aspect 112 provides the system of any of Aspects 83-111, wherein the system provides a recycled continuous carbon fiber strand that has a strength selected from the group consisting of:at least 50% of that of a comparable newly fabricated strand, at least 70% of that of a comparable newly fabricated strand, at least 85% of that of a comparable newly fabricated strand;at least 90% of that of a comparable newly fabricated strand; and at least 95% of that of a comparable newly fabricated strand.

[0279] Aspect 113 provides the system of any of Aspects 83-112, wherein the system provides a recycled continuous carbon fiber strand that has a length selected from the group consisting of:at least 25 mm,at least 10 cm,at least 1 m,at least 10 m,at least 100 m,at least 25% of a length of the carbon fiber strand as wound prior to recycling,at least 50% of length of the carbon fiber strand as wound prior to recycling,at least 80% of length of the carbon fiber strand as wound prior to recycling,at least 90% of length of the carbon fiber strand as wound prior to recycling,at least 95% of length of the carbon fiber strand as wound prior to recycling, andAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTat least 99% of the carbon fiber strand as wound prior to recycling.

[0280] Aspect 114 provides the system of any of Aspects 83-113, wherein the at least one carbon fiber strand comprises a plurality of carbon fiber strands and the at least one bare carbon fiber strand comprises a plurality of bare carbon fiber strands.

[0281] Aspect 115 provides the system of any of Aspects 83-114, wherein acetic acid provides, at least in part, the polymer swelling component and the catalyst component.

[0282] Aspect 116 provides the system of Aspect 115, wherein the acetic provides at least a portion of the reactive chemical solution selected from the group consisting of: (A) at least 1%, (B) at least 3%, (C) at least 5%, (D) at least 10%, (E) at least 20%, (F) at least 40%, (G) at least 80%, (H) no more than 100%, (I) no more than 90%, (J) no more than 85%, and (K) no more than 80%.

[0283] Aspect 117 provides a system for recycling fiber from a thermoset composite, comprising:a reaction chamber configured to hold a thermoset composite component;a vapor generation system configured to introduce a catalyst-containing vapor into the reaction chamber; anda temperature control system configured to maintain the reaction chamber at an elevated temperature sufficient to cause chemical degradation of thermoset resin in the thermoset composite component.

[0284] Aspect 118 provides the system of Aspect 117, wherein the fiber comprises carbon fiber or glass fiber.

[0285] Aspect 119 provides the system of any of Aspects 117 or 108, wherein the reaction chamber is configured to maintain elevated pressure and further comprises a pressure control system.

[0286] Aspect 120 provides the system of any of Aspects 117-119, further comprising a condensation system configured to remove degraded resin products and separate degraded resin products from the catalystcontaining vapor.

[0287] Aspect 121 provides the system of Aspect 120, wherein theAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTvapor generation system comprises a reconditioning unit configured to recondition the catalyst-containing vapor.

[0288] Aspect 122 provides the system of any of Aspects 117-121, wherein the catalyst-containing vapor comprises a catalyst solution comprising an aqueous solution of an organic salt and a polymer swelling material.

[0289] Aspect 123 provides the system of Aspect 122, wherein the organic salt comprises zinc acetate and the polymer swelling material comprises acetic acid.

[0290] Aspect 124 provides the system of any of Aspects 117-123, further comprising a washing station comprising a tank containing a polar washing solvent for subjecting recovered fiber to a liquid washing solution.

[0291] Aspect 125 provides the system of any of Aspects 117-124, further comprising a fiber separation station comprising an unwinding mechanism with guide rollers and a winding mechanism for collecting separated fiber.

[0292] Aspect 126 provides the system of Aspect 125, wherein the fiber separation station further comprises a moisture reduction system comprising a nip roller, a heating element, or a desiccant.

[0293] Aspect 127 provides the system of any of Aspects 117-124, wherein the temperature control system is configured to maintain temperature in a range of 150°C to 300°C without causing thermal degradation of the thermoset resin.

[0294] Aspect 128 provides the system of any of Aspects 119-127, wherein the pressure control system is configured to maintain pressure in a range of 400 psi to 1000 psi.

[0295] Aspect 129 provides the system of any of Aspects 117-128, wherein the reaction chamber is configured to hold the thermoset composite component suspended above liquid.

[0296] Aspect 130 provides the system of any of Aspects 117-129, further comprising at least one sensor configured to detect resin removal and a controller configured to determine reaction completion based on sensor input.

[0297] Aspect 131 provides the system of any of Aspects 117-130,Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTfurther comprising a vapor circulation system configured to flow vapor around the component.

[0298] Aspect 132 provides the system of any of Aspects 117-131, wherein the system is configured to process a pressure vessel, a wind turbine blade component, an aerospace component, a sports equipment component, a construction component, or an automotive component.

[0299] Aspect 133 provides the system of any of Aspects 117-132, wherein the system is configured to process continuous fiber strands or fabric segments.

[0300] Aspect 134 provides the system of any of Aspects 117-133, further comprising a catalyst recovery system for reclaiming catalyst from degraded resin products.

[0301] Aspect 135 provides the system of any of Aspects 117-134, further comprising a rinse bath comprising room temperature water positioned to receive fiber after resin removal.

[0302] Aspect 136 provides the system of any of Aspects 117-135, configured to recover at least 90% of fiber from the thermoset composite component while recovering fiber retaining at least 70% of virgin fiber strength.

[0303] Aspect 137 provides the system of any of Aspects 117-136, wherein the reaction chamber comprises at least one location for collecting degraded resin products.

[0304] Aspect 138 provides the system of any of Aspects 117-137, further comprising a filtration system for the catalyst-containing vapor.

[0305] Aspect 139 provides the system of any of Aspects 117-138, wherein the catalyst-containing vapor comprises about 70 wt.% water, about 20 wt.% zinc acetate, and about 10 wt.% acetic acid.

[0306] Aspect 140 provides the system of any of Aspects 117-139, wherein the system is configured to process filament wound composite components without requiring disassembly or sectioning.

[0307] Aspect 141 provides the system of any of Aspects 117-140, wherein the vapor generation system is configured to maintain the catalystcontaining vapor at a temperature between 180°C and 250°C and a pressureAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTbetween 500 psi and 800 psi for a period between 2 hours and 12 hours.

[0308] Aspect 142 provides the system of any of Aspects 117-141, further comprising an automated control system configured to monitor process parameters and adjust temperature, pressure, or vapor composition during operation.

[0309] Aspect 143 provides the system of any of Aspects 117-142, wherein the system comprises a vapor flow path configured to direct catalystcontaining vapor from the vapor generation system through the reaction chamber to a condensation system.

[0310] Aspect 144 provides the system of any of Aspects 125-135, wherein the fiber separation station comprises tension monitoring equipment configured to maintain consistent tension during unwinding.

[0311] Aspect 145 provides the system of any of Aspects 117-144, configured to recover continuous carbon fiber strands having lengths of at least 1 meter.

[0312] Aspect 146 provides the system of any of Aspects 124-145, wherein the washing station comprises multiple rollers configured to guide fiber through washing solvent.

[0313] Aspect 147 provides the system of any of Aspects 117-146, wherein the system is configured to operate in a continuous or batch processing mode.

[0314] Aspect 148 provides the system of any of Aspects 117-147, wherein the reaction chamber comprises a sealable autoclave.

[0315] Aspect 149 provides the system of any of Aspects 117-148, wherein the catalyst-containing vapor comprises a metal cation selected from the group consisting of: Zn2+, Fe3+, Fe2+, Cu2+, Mn3+, Mn2+, Co3+, Ni2+, and Ni3+.

[0316] Aspect 150 provides the system of any of Aspects 117-149, further comprising a degraded resin collection system configured to separate and store degraded resin products for subsequent recycling.

[0317] Aspect 151 provides the system of any of Aspects 117-150, wherein the system is configured to process composite components comprising epoxy or polyurethane resin systems.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0318] Aspect 152 provides the system of any of Aspects 125-151, wherein the unwinding mechanism comprises variable-speed control to minimize mechanical stress on fibers.

[0319] Aspect 153 provides the system of any of Aspects 117-152, configured to preserve at least 99% of continuous carbon fibers from the thermoset composite component.

[0320] Aspect 154 provides the system of any of Aspects 117-153, further comprising a fiber storage system comprising spools or holders for storing recovered fiber.

[0321] Aspect 155 provides the system of any of Aspects 124-154, wherein the washing station is positioned separately from the reaction chamber.

[0322] Aspect 156 provides the system of any of Aspects 117-155, wherein the temperature control system comprises heating elements and temperature sensors.

[0323] Aspect 157 provides the system of any of Aspects 117-156, further comprising a vapor reconditioning loop configured to maintain catalyst concentration within a target range.

[0324] Aspect 158 provides the system of any of Aspects 117-157, configured to avoid char formation during resin degradation.

[0325] Aspect 159 provides the system of any of Aspects 117-158, wherein the system comprises multiple processing stations including a resin removal station, a washing station, and a fiber separation station.

[0326] Aspect 160 provides the system of Aspect 159, wherein the fiber separation station comprises an actuatable wrapping guide.

[0327] Aspect 161 provides the system of any of Aspects 117-160, configured to handle composite components having multiple layers of wound carbon fiber.

[0328] Aspect 162 provides the system of any of Aspects 117-161, wherein the catalyst-containing vapor comprises a polymer swelling material selected from the group consisting of: a weak organic acid, acetic acid, citric acid, formic acid, and HNCh.

[0329] Aspect 163 provides the system of any of Aspects 117-162,Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTwherein the system is configured to operate at temperatures above vaporization temperature of the catalyst-containing vapor but below pyrolysis temperature of the thermoset resin.

[0330] Aspect 164 provides the system of any of Aspects 117-163, further comprising alarm systems configured to alert operators to process deviations or completion.

[0331] Aspect 165 provides the system of any of Aspects 117-164, wherein the vapor generation system comprises a vaporization vessel separate from the reaction chamber.

[0332] Aspect 166 provides the system of any of Aspects 117-165, wherein the system is modular and comprises interchangeable components for different composite types or sizes.

[0333] Aspect 167 provides the system of any of Aspects 117-166 wherein the catalyst comprises a material selected from the group consisting of zinc chloride, aluminum chloride, boron trifluoride, titanium tetrachloride, NaOCl, and tripotassium phosphate.

[0334] Aspect 168 provides the system of any of Aspects 117-167 wherein the catalyst comprises a material selected from the group consisting of: a weak organic acid , a weak organic acid including acetic acid (e.g. in glacial form), a weak organic acid including formic acid (e.g. in anhydrous form).

[0335] Aspect 169 provides the system of Aspect 162, wherein the catalyst and the swelling material comprise the same material.

[0336] Aspect 170 provides the system of Aspect 169, wherein the catalyst and the swelling material both comprise acetic acid

[0337] Aspect 171 provides the system of Aspect 169, wherein the catalyst and the swelling material comprise different materials.

[0338] Aspect 172 provides a method for recycling at least one continuous carbon fiber fabric segment from at least one component wherein the at least one carbon fiber fabric segment is embedded in solidified thermoset resin to obtain at least one carbon fiber fabric segment configured for reuse, comprising:Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTproviding a reaction chamber for removing solidified thermoset resin from the carbon fiber fabric segment wherein the chamber is configured to hold a vapor solution at a specified reaction temperature and a specified reaction pressure, for a specified reaction duration, and wherein the chamber has at least one first location for holding at least one component and at least one location for receiving degraded resin reaction products;locating the at least one component to be recycled at the at least one first location of the reaction chamber;introducing a vaporized reactive chemical solution into the reaction chamber and maintaining the vapor at a specified reaction temperature, at a specified reaction pressure, and for a specified reaction duration to provide effective removal of the solidified thermoset resin from the carbon fiber fabric segment forming part of the component to provide a bare carbon fiber fabric segment remaining on the component in an undamaged state;wherein the chemical solution comprises:a catalyst solution comprising a catalyst dissolved in a solvent, anda polymer swelling material that is miscible with the catalyst solution;wherein the specified reaction temperature and pressure provide for chemical degradation of the solidified resin, with the temperature and pressure holding the reactive chemical solution in a vaporized state around the component while also being appropriate to avoid causing thermal degradation of the solidified resin or its reaction products;subjecting the component having bare carbon fiber to a liquid washing solution to wash away residual reactive chemical solution; andremoving the bare carbon fiber fabric segment from any remaining part of the component and retaining the removed carbon fiber fabric segment for future use.

[0339] Aspect 173 provides the system of Aspect 172, wherein the catalyst comprises a material selected from the group consisting of: a weak organic acid, a weak organic acid including acetic acid (e.g. in glacial form), a weak organic acid including formic acid (e.g. in anhydrous form).Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT

[0340] Aspect 174 provides the system of any of Aspects 172 or 173, wherein the catalyst and the swelling material comprise the same material.

[0341] Aspect 175 provides the system of Aspect 174, wherein the catalyst and the swelling material both comprise acetic acid.

[0342] Aspect 176 provides the system of any of Aspects 172 or 173, wherein the catalyst and the swelling material comprise different materials.

[0343] Aspect 177 provides a system for recycling at least one continuous carbon fiber fabric segment from at least one component wherein the at least one carbon fiber fabric segment is embedded in solidified thermoset resin to obtain at least one carbon fiber fabric segment configured to reuse, comprising:a reaction chamber for removing solidified thermoset resin from at least one carbon fiber fabric segment wherein the chamber is configured to hold a vapor solution at a specified reaction temperature and a specified reaction pressure, for a specified reaction duration, and wherein the chamber has at least one first location for holding the at least one component and at least one location for receiving degraded resin reaction products;a reactive chemical solution configured to be introduced into the reaction chamber and configured while in a vaporized state to surround a component to be recycled and being maintained in the vaporized state at a specified reaction temperature, at a specified reaction pressure, and for a specified reaction duration to provide effective removal of solidified thermoset resin from the at least one carbon fiber fabric segment to provide at least one bare carbon fiber fabric segment with the at least one bare carbon fiber fabric segment remaining on the component in an undamaged state;wherein the chemical solution comprises:a catalyst solution comprising a catalyst dissolved in a solvent, anda polymer swelling material that is miscible with the catalyst solution;wherein the specified reaction temperature and pressure provide for chemical degradation of the solidified resin, with the temperature and pressure holding the reactive chemical solution in a vaporized state around the at leastAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTone component while also being appropriate to avoid causing thermal degradation of the solidified resin or its reaction byproducts;a washing station for subjecting the at least one bare carbon fiber fabric segment to a liquid washing solution to wash away residual reactive chemical solution; andremoving the bare carbon fiber fabric segment from any remaining part of the at least one component and retaining the removed carbon fiber fabric segment for future use.

[0344] Aspect 178 provides the system of Aspect 177, wherein the catalyst comprises a material selected from the group consisting of: a weak organic acid , a weak organic acid including acetic acid (e.g. in glacial form), a weak organic acid including formic acid (e.g. in anhydrous form).

[0345] Aspect 179 provides the system of any of Aspects 177 or 178, wherein the catalyst and the swelling material comprise the same material.

[0346] Aspect 180 provides the system of Aspect 179, wherein the catalyst and the swelling material both comprise acetic acid.

[0347] Aspect 181 provides the system of any of Aspects 177 or 178, wherein the catalyst and the swelling material comprise different materials.ADDITIONAL REMARKS

[0348] Materials referenced herein are incorporated herein by reference as if set forth in full. To the extent that any definitions or other teachings set forth in material incorporated herein by reference contradict teachings set forth directly herein (i.e. , not incorporated by reference), the order of precedence given to the definitions or other teachings are: (1) teachings set forth directly in the body of the application, and then (2) teachings set forth in incorporated material with material having more recent publication dates s taking precedence over material with older dates.

[0349] It is intended that the aspects of the disclosure set forth specifically herein or otherwise ascertained from the present teachings represent independent disclosure descriptions which Applicant contemplates as full and complete, and that Applicant believes may be set forth as independent claims orAttorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTdependent claims without need of importing additional limitations or elements from other aspects for interpretation or clarification.

[0350] While various preferred aspects of the disclosure are show n and described, it is to be distinctly understood that this disclosure is not limited thereto but may be variously embodied to practice within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the disclosure as defined by the following claims.

Claims

Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCTWHAT IS CLAIMED IS:What is claimed is:

1. A method for recycling carbon fiber from a composite component, comprising:providing a component comprising carbon fiber embedded in solidified thermoset resin;exposing the component to a reactive vapor comprising a catalyst at an elevated temperature for a period of time sufficient to at least partially degrade the solidified thermoset resin; andseparating at least a portion of the carbon fiber from the component.

2. The method of claim 1, wherein the reactive vapor comprises a catalyst solution comprising the catalyst dissolved in a solvent and a polymer swelling material that is miscible with the catalyst solution.

3. The method of claim 2, wherein the catalyst comprises at least one of a weak organic acid, acetic acid, formic acid, zinc chloride, aluminum chloride, boron trifluoride, titanium tetrachloride, NaOCl, tripotassium phosphate, or a metal cation selected from the group consisting of: Zn2+, Fe3+, Fe2+, Cu2+, Cu+. Cr3+, Cr2+, Mn3+, Mn2+, Co3+, Ni2+, Ni3+, Sn2+, Sn4+, Pb2+, and Pb4+.

4. The method of claim 2 or 3, wherein the polymer swelling material comprises a material selected from the group consisting of: a weak organic acid, acetic acid, citric acid, formic acid, and HNOs.

5. The method of any of claims 1-4, wherein the elevated temperature is maintained without causing thermal degradation of the solidified thermoset resin and the elevated temperature is in a range selected from the group consisting of: 150°C to 300°C; 180°C to 250°C; and 180°C to 200°C.

6. The method of any of claims 1-5, wherein exposing the component occurs in a reaction chamber maintained at an elevated pressure.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT7. The method of claim 6, wherein the elevated pressure is in a range selected from the group consisting of 400 psi to 1000 psi; 500 psi to 800 psi; and 500 psi to 600 psi.

8. The method of any of claims 1-7, wherein the period of time is in a range selected from the group consisting of: 1 hour to 48 hours; 2 hours to 12 hours; and 4 hours to 8 hours.

9. The method of any of claims 1-8, wherein the carbon fiber comprises at least one continuous carbon fiber strand that remains wound after separation.

10. The method of claim 9, wherein the at least one continuous carbon fiber strand has a length selected from the group consisting of: at least 25 mm, at least 10 cm, at least 1 m, at least 10 m, and at least 100 m, at least 200 m, at least 500 m, at least 1 km, at least 2 km, at least 5 km, and at least 10 km.

11. The method of any of claims 1-10, further comprising subjecting the separated carbon fiber to a liquid washing solution comprising a highly polarized solvent selected from the group consisting of: water, glycerol, an alcohol, methanol, ethanol, dimethyl sulfoxide, acetone, and dimethylformamide.

12. The method of any of claims 1-11, wherein the solidified thermoset resin comprises an epoxy or a polyurethane.

13. The method of any of claims 1-12, wherein the reactive vapor comprises about 70 wt.% water, about 20 wt.% zinc acetate, and about 10 wt.% acetic acid.

14. The method of any of claims 1-13, wherein degraded resin reaction products are collected and recycled for reuse.

15. The method of claim 14, wherein the catalyst captured by the degraded resin products is reclaimed for reuse.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT16. The method of any of claims 1-15, wherein the separated carbon fiber retains at least 70% of a tensile strength of virgin carbon fiber and has a length of at least 25% of an original fiber length in the component.

17. The method of any of claims 1-16, wherein the method recovers at least 90% of the carbon fiber from the component.

18. The method of any of claims 1-17, wherein the catalyst comprises acetic acid, which also provides polymer swelling.

19. The method of claim 18, wherein the acetic acid provides at least a portion of the reactive vapor is selected from the group consisting of: (A) at least 1%, (B) at least 3%, (C) at least 5%, (D) at least 10%, (E) at least 20%, (F) at least 40%, (G) at least 80%, (H) no more than 100%, (I) no more than 90%, (J) no more than 85%. and (K) no more than 80%.

20. A system for recycling fiber from a thermoset composite, comprising:a reaction chamber configured to hold a thermoset composite component; a vapor generation system configured to introduce a catalyst-containing vapor into the reaction chamber; anda temperature control system configured to maintain the reaction chamber at an elevated temperature sufficient to cause chemical degradation of thermoset resin in the thermoset composite component.

21. The system of claim 20, wherein the fiber comprises carbon fiber or glass fiber.

22. The system of claim 20 or 21, wherein the reaction chamber is configured to maintain elevated pressure and further comprises a pressure control system.

23. The system of any of claims 20-22, further comprising a condensation system configured to remove degraded resin products and separate degraded resin products from the catalyst-containing vapor.Attorney Docket No. 6323.053 WO1 Client Ref. No. 32911-E PCT24. The system of claim 23, wherein the vapor generation system comprises a reconditioning unit configured to recondition the catalyst-containing vapor.

25. The system of any of claims 20-24, wherein the catalyst-containing vapor comprises a catalyst solution comprising an aqueous solution of an organic salt and a polymer swelling material.

26. The system of claim 25, wherein the organic salt comprises zinc acetate and the polymer swelling material comprises acetic acid.

27. The system of any of claims 20-26, wherein the catalyst-containing vapor comprises about 70 wt.% water, about 20 wt.% zinc acetate, and about 10 wt.% acetic acid.

28. The system of any of claims 20-27, wherein the catalyst containing solution comprises a catalyst material selected from the group consisting of: a weak organic acid, a weak organic acid including acetic acid, and a weak organic acid including formic acid.

29. The system of claim 25 or 26, wherein the catalyst and the swelling material comprise the same material.

30. The system of claim 29, wherein the catalyst and the swelling material both comprise acetic acid.

Images