Additive manufacturing of in-SITU thermotropic liquid crystal polymer fibers

Abstract

A thermotropic polymer article which includes discrete continuous polymer fibers which are encapsulated by a bulk polymer, wherein the continuous fiber and the bulk polymer are melt processable and wherein both the polymer fiber and bulk polymer are created during an extrusion process.

Description

ADDITIVE MANUFACTURING OF IN-SITU THERMOTROPIC LIQUID CRYSTAL POLYMER FIBERSBACKGROUND

[0001] Additive manufacturing allows companies and individuals to independently create desired articles quickly and inexpensively. However, there is a growing demand for additive feedstock and associated manufacturing methods which enable stronger and less expensive articles to be easily built. Trends in recent years have been to create strong properties which rival metals like aluminum. In the last few years "super-polymers" have been implemented such as ULTEM, PEEK, PAEK. These materials enable strong articles, but the methods of using such polymers can be expensive and require specialized additive machinery. In addition, fillers such as chopped carbon fiber and glass fibers, which are made ex-situ, have been added to create stronger compounds, mirroring what has been done in the injection molding industry. The original polymers used in the Fused Deposition Modeling process were materials such as PLA and ABS. These materials tensile strengths in the 40-50 MPa ranges and Young's modulus in the 1-3 GPa range. The uses of "Super polymers" have increased the strengths to up to 100 MPa, with fibers up to 125 MPa and Young's modulus has increased tolO MPa.

[0002] The industry has also moved to trying to match mechanical properties of aluminum parts. To achieve this there has been an effort to include pre-made "continuous" fibers such as carbon, Kevlar, and glass fibers. Some companies have created a composite fiber in which extruded nylon is positioned around a premade or ex-situ continuous fiber and have developed a specialized printer to place and cut the fibers while printing. Mechanical properties achieved with these techniques are Tensile strengths in excess of 600 MPa and Young's Modulus more than 40 MPa.

[0003] Since the printing process is extremely complex with continuous fibers, there remains a need to improve additive feedstock which can be used in manufacturing to produce stronger articles without the need to specialized printers or complicated methods.SUMMARY OF THE INVENTION

[0004] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify keyor essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0005] This invention accomplishes the goal of creating parts with metal-like properties by creating fibers in-situ, instead of using fibers like carbon, glass, or Kevlar which are typically produces ex-situ and added via complicated processes using expensive machinery. These prior art fibers are all created with specialized processes, and the fibers cannot be created using melt extrusion. For example, Kevlar is a liquid crystal polymer material, which is lyotropic, and can only be processed into a fiber by using sulfuric acid.

[0006] This invention relates to using "melt processable" thermoplastics ("thermotropic") which can be extruded into fibers in the extrusion process parameters which are available with current 3D printers In addition the prior art "super polymers" are typically processed on high end expensive printers, which the nozzle temperature needed are > 350C. In an aspect, this invention uses polymers with melt temperatures in line with mass produced consumer product printers which have nozzle temperatures < =350C.

[0007] In one aspect, embodiments disclosed herein relate to a thermotropic polymer article created by an extrusion process, which includes discrete continuous polymer fibers which are encapsulated by a bulk polymer. The continuous fiber and the bulk polymer are melt processable and the polymer fibers are created during the extrusion process. The polymer fibers can comprise PEEK, thermoplastic liquid crystal polymer, Nylon, or other polymer that can be extruded as a continuous polymer fiber. When the polymer fiber comprises thermoplastic liquid crystal, the thermoplastic liquid crystal polymer may comprise a hydroxybenzoic acid repeat unit and or a.hydroxynaphthoic acid repeat unit and is a thermotropic mesogen when in the molten state.

[0008] The extrusion process is an additive printing process in another aspect, and the polymer fiber can be melt processed at or less than 350C. The fibers are extruded into a chamber the temperature of which is less than 80C and greater than 25C, and extend in a first direction, with the tensile strength of the article produced greater than 200 MPa in a first direction. The polymer fibers enable the Young's modulus of the article to be greater than 10 GPa.

[0009] In another aspect, the extrusion process creates the article by laying down polymer in layers, and the polymer fibers are created on distinct layers. The extrusion process creates the article by laying down polymer in planar layers, wherein a plurality of thepolymer fibers are created on distinct layers and extend throughout the distinct layers, and thermoplastic liquid crystal polymer is dispersed throughout the article and bonded to the fibers. The polymer fibers can be aligned in a parallel direction, where a portion of the polymer fibers are aligned in a first direction, and a second portion of the polymer fibers are aligned in a second direction, arranged in a mesh, or otherwise printed to provide strength in the article where it is desired.

[0010] In an aspect the extrusion process is an additive printing process performed with at least one extrusion nozzle, and the extrusion nozzle has an internal diameter equal to or less than 0.2 mm, the extrusion nozzle extrudes the polymer at a temperature between 335C and 350C, and the extrusion nozzle extrudes the polymer at a rate between 275 and 440 mm / s.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIGs. 1A-F and 2A-C are perspective representations of polymer articles including aspects of the invention.

[0012] FIGs.3A and 3B shows a graph describing the relationship between heat flow verses temperature, and inverse half crystalline time v temperature respectively, which are more fully described in Example 6.

[0013] FIG.4 shows a graph describing the relationship between Z direction tensile strength and extrusion temperature which is more fully described in Example 8.

[0014] FIG. 5 shows a graph describing the relationship between Z direction tensile strength and printing layer height which are more fully described in Example 8.

[0015] FIG. 6 shows a graph describing the relationship between Z direction tensile strength and printing speed which are more fully described in Example 8.DETAILED DESCRIPTIONTLCPs and mesogenic TLCP

[0016] There are three types of Liquid Crystal polymers that have been developed for industrial applications. All are based on the utilization of hydroxybenzoic acid. Type I was the first and used by Sumitomo and Solvay, have the highest heat deflection temperature and are used mainly for connectors. Type II and Type III are "copolymers" which havebeen developed to lower the temperature resistance and to optimize the processing of LCPs.

[0017] In an aspect, this invention relates to both homopolymers and copolymers of HBA. (hydroxybenzoic acid).Type Molecular Structure TDUL

[0018] LCPs are typically derived from monomers that include aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aliphatic dicarboxylic acids, aromatic diols, aliphatic diols, aromatic hydroxyamines, and / or aromatic diamines. For example, they may be aromatic polyesters that are obtained by polymerizing one or two or more aromatic hydroxycarboxylic acids; aromatic polyesters obtained by polymerizing aromatic dicarboxylic acids, one or two or more aliphatic dicarboxylic acids, aromatic dials, and one or two or more aliphatic dials, or aromatic hydroxycarboxylic acids; aromatic polyesters obtained by polymerizing one or two or more monomers selected from a group including aromatic dicarboxylic acids, aliphatic dicarboxylic acids, aromatic diols, and aliphatic dials, aromatic polyester amides obtained by polymerizing aromatic hydroxyamines, one or two or more aromatic diamines, and one or two or more aromatic hydroxycarboxylic acids; aromatic polyester amides obtained by polymerizing aromatic hydroxyamines, one or two or more aromatic diamines, one or two or more aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, and one or two or more aliphatic carboxylic acids; and aromatic polyester amides obtained by polymerizing aromatic hydroxyamines, one or two or more aromatic diamines, one or two or more aromatic hydroxycarboxylic acids,aromatic dicarboxylic acids, one or two or more aliphaticcarboxylic acids, aromatic diols, and one or two or more aliphatic diols.

[0019] Examples of aromatic hydroxycarboxylic acids include 4-hydroxybenzoic acid, 3- hydroxybenzoic acid, 2-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and halogen-, alkyl-, or a llyl-su bstituted derivatives of hydroxybenzoic acid.

[0020] Examples of aromatic dicarboxylic acids include terephthalic acid; isophthalic acid; 3,3'-diphenyl dicarboxylic acid; 4,4'-diphenyl dicarboxylic acid; 1,4-naphthalene dicarboxylic acid; 1,5-naphthalene dicarboxylic acid; 2,6-naphthalene dicarboxylic acid; and alkyl- or halogen-substituted aromatic dicarboxylic acids, such as t-butylterephthalic acid, chloroterephthalic acid, etc.

[0021] Examples of aliphatic dicarboxylic acids include cyclic aliphatic dicarboxylic acids; such as trans-l,4-cyclohexane dicarboxylic acid; cis-l,4-cyclohexane dicarboxylic acid; 1,3- cyclohexane dicarboxylic acid; and substituted derivatives thereof.

[0022] Examples of aromatic diols include hydroquinone; biphenol; 4,4'- dihydroxydiphenyl ether; 3,4'-dihydroxydiphenyl ether; bisphenol A; 3,4'- dihydroxydiphenylmethane; 3,3'-dihydroxydiphenylmmethane; 4,4'- dihydroxydiphenylsulfone; 3,4'-dihydroxydiphenylsulfone; 4,4'-dihydroxydiphenylsulfide; 3,4'-dihydroxdiphenylsulfide; 2,6'-naphthalenediol; l,6'-naphthalenediol; 4,4'- dihydroxybenzophenone; 3,4'-dihydroxybenzophenone; 3,3'-dihydroxybenzophenone; 4,4'-dihydroxydiphenyldimethylsilane; and alkyl- and halogen-substituted derivatives thereof.

[0023] Examples of aliphatic dials include cyclic, linear, and branched aliphatic diols, such as trans-l,4-hexanediol; cis-l,4-hexanediol; trans-l,3-cyclohexanediol; cis-1,2- cyclohexanediol; ethylene glycol; 1,4-butanediol; 1,6-hexanediol; 1,8-octanediol; trans- 1,4-cyclohexanedimethanol; cis-l,4-cyclohexanedimethanol; etc., and substituted derivatives thereof.

[0024] Examples of aromatic hydroxyamines and aromatic diamines include 4- aminophenol, 3-aminophenol, p-phenylenediamine, m-phenylenediamine, and substituted derivatives thereof.

[0025] The one or more LCPs may be produced using any method known in the art. For example, they can be produced by standard polycondensation techniques (melt polymerization, solution polymerization, and solid-phase polymerization). In someembodiments, it is desirable for the LCP to be produced in an inert gas atmosphere under anhydrous conditions. For example, in the melt acidolysis method, the necessary quantities of acetic anhydride, 4-hydroxybenzoic acid, diol, and terephthalic acid are stirred, after which they are heated in a reaction vessel provided with a combination of a nitrogen introduction tube and a distillation head or cooler; the side reaction products, such as acetic acid, are removed through the distillation head or cooler, after which they are collected. After the quantity of collected side reaction products becomes constant, and the polymerization is almost completed, the melted lump is heated under a vacuum (ordinarily, 10 mmHg or lower) and the remaining side reaction products are removed, completing the polymerization.

[0026] In some embodiments, the one or more LCPs have number average molecular weights in the range of about 2,000 to about 200,000. In other embodiments, the LCPs have number average molecular weights in the range of about 5,000 to about 50,000. In other embodiments, the LCPs have number average molecular weights in the range of about 10,000 to about 20,000. Molecular weight may affect melt viscosity of the LCP.

[0027] The one or more LCPs included in the LCP composite are preferably thermoplastic polyester polymers containing rigid mesogenic linkages. In some embodiments, the one or more LCP polymers have crystalline melting points in the range of about 250° C. to 375° C. In other embodiments, the one or more LCP polymers more have crystalline melting points in the range of about 270° C. to 355° C.

[0028] The one or more LCPs may be classified as neat polymers in that, prior to combination with the one or more fillers, they are not reinforced by, filled / mixed with, or otherwise modified by additional material.

[0029] Exemplary LCPs that may be used in the film are thermoplastic polyester polymers including monomer units derived from 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; thermoplastic polyester polymers including monomer units derived from 6-hydroxy- 2-naphthoic acid, terephthalic acid, and acetaminophen; and thermoplastic polyester polymers including monomer units derived from 4-hydroxybenzoic acid, terephthalic acid and 4, 4'-biphenol.

[0030] Exemplary LCPs are those available from Celanese Corporation under the trademark VECTRA®. These include VECTRA® A polymer (e.g., VECTRA® A950), VECTRA® B polymer (e.g., VECTRA® B950), VECTRA® C polymer (e.g., VECTRA® C950).

[0031] VECTRA® A polyester includes 73 mole % of monomer units derived from 4- hydroxybenzoic acid ("HBA") having the formula

[0032] and 27 mole % of monomer units derived from 2,6-hydroxynaphthoic acid ("HNA") having the formula:

[0033] VECTRA® A950 has a melting point of about 278° C.

[0034] VECTRA® B polyester includes 60 mole % of monomer units derived from HNA, 20 mole % of monomer units derived from TA, and 20 mole % of monomer units derived from acetaminophenol having the formula:

[0035] VECTRA® B950 has a melting point of about 280° C.

[0036] VECTRA® C polyester includes 80 mole % of monomer units derived from HBA and 20 mole % of monomer units derived from HNA. VECTRA® C950 has a melting point of about 320° C.

[0037] These liquid crystal polymers are thermotropic as they achieve the liquid crystal state by melting. These thermotropic liquid crystal polymers form thermally activated mesogenic phases that extend from the crystal melting temperature to the isotropic or transition temperature. Thus as the thermotropic liquid crystal polymer melts the mesogenic polymers orient themselves into a liquid crystalline phase which persists when the polymer temperature is lowered and polymer hardens. The liquid crustal polymers molecules have a parallel packing arrangement or microdomain. The direction of these microdomains can be engineering to provide strength as the polymer is strongest in the direction of its orientation. These microdomains can be detected via x-ray diffraction, andpowder X-ray scattering along with polarized light microscopy and Differential Scanning Calorimetry techniques are useful in identifying the phase and packing structure of liquid crystal polymers.

[0038] Printing in-situ fibers

[0039] Printing multicomponent articles with in-situ fibers

[0040] In an aspect, TLPC fibers are printed as infill to achieve high strengths in a desired article. When test bars are made only one shell is used to print the part so that the rest of the part can be filled with high strength fibers. To print fibers the nozzle needs to be 280C- 350C, the hotter the better if the printer is capable, speed of 117mm / s minimum, and a layer height of .05 with the nozzle width set to ,4mm on a ,4mm nozzle with 100% infill. The part also needs a hot build environment to ensure decent interlayer adhesion, 45C- 65C minimum and 120C is ideal on a high temp printer.

[0041] Printing like this creates ,05mm by ,4mm flat fibers throughout the whole part. Depending on where and how the strength is needed, the infill pattern can be changed. For tensile bars an aligned rectilinear pattern is used, and the angle of the pattern is set to go along the long direction of the bars. This ensures that all the fibers are laid in the direction of the force that is being applied. Other patterns can be applied to create more of a distribution of strength across the part. Some examples would be an alternating cross hatching pattern that is similar to the one used in the field of composites for a more isotropic strength or a concentric pattern for rigidity and complex shapes where strength is needed in all different directions. All these patterns and settings are built into off the self 3D printing slicer software, no proprietary or extra software is needed to generate the printing files to make fiber filled parts with TLPC.

[0042] This printing technique of printing fibers outlined above, might be applicable to other 3D printing materials. Poly ether ketone (Pek), Poly ether ether ketone (Peek), Polyether Imide (PEI), Copolyester (CPE), Polyamide (Nylon), Polypropylene (PP), Polyethylene (PE), Polymethyl Methacrylate (Acrylic), Polyvinyl Chloride (PVC), Polycarbonate (PC), and Polyethylene Terephthalate (PET) are all polymers that are turned into fibers and are also available on the market as a filament for 3D printing. A lot of them might be very hard or impossible to print with the proper parameters to generate fibers from printing due to the high speed and very small layer height needed but it may be possible. If it is possible, they would not benefit as much as printing TLPC fibers. Therecould be a marginal increase of mechanical properties from printing fibers in parts with those materials but not significant enough to compete with TLPC. Due to TLPC's rheology, viscosity, crystallinity, and ability to print at small layer heights it is probably the perfect candidate for in situ printing of fibers in a part.

[0043] Printing TLPC on low cost, consumer, non-high temperature printers:

[0044] Due to the melting temperature of TLPC and how quickly it cools, it is preferred that it is printed in a high temperature printer with a high temperature heated chamber, 120C. A printer that can achieve 300-350C at the nozzle, 120C build bed, an enclosed chamber, and a fast printing speed (>300mm / s) is capable of printing TLPC. With a higher printing speed, the layers do not fully cool down before the next layer is printed on top allowing for layer adhesion and fiber production at lower temperatures.

[0045] The failure mode of TLPC is not like other 3D printed parts; it is more like a composite part or an organic object with fibers like a tree branch. A failure is due to interlayer delamination and then the fibers breaking. The break is not clean and usually the part is not completely separated into two pieces. On failure, not all fibers may break, and the density of fibers all bundled together create friction that keeps the broken part as one until it is further separated. A failed part usually exhibits an expansion of fibers localized around the main point of break in the part.

[0046] Printing fully TLPC parts may not fit all applications or fit every budget, with dual nozzle 3d printers TLPC fibers can be printed in situ with other conventional 3D printing polymers creating composite parts. This takes advantage of TLPC's strength and stiffness while using cheaper materials for bulk of the composition of the part.

[0047] This process involves creating fibers in the same way as stated above but encapsulating it in the matrix material or secondary polymer (your chosen filament i.e. Polylactic Acid (PLA)) during printing. TLPC does not have great adhesion to other materials (most other polymers of different compositions in 3D printing do not adhere well to each other either) so to get the strength and adhesion you must fully encapsulate the fibers in the matrix material. The printing layers consist of solid layers of the matrix material at a chosen layer height (the matrix layer) followed by a layer with lines of TLPC as the infill with lines of matrix material running between the lines of the TLPC and as the perimeters at a layer height of ,05mm (the composite layer). Those layers then alternate throughout the mode to create a composite part. With PLA and TLPC an increase of about 400% intensile strength was observed versus just PLA alone. These tests were done at ,05mm layer height for both solid and composite layers and with a 21% fiber loading density. With fine tuning these results should be translatable to other common 3D printing materials, not just PLA.

[0048] In an aspect a slicer or addon for a slicer is implemented to get correct layering and tool paths for the materials. In an aspect, the slicing is being done by using Creatware, a modified version of Prusaslicer for Creatbot printers. In the slicer, custom layer heights were set to alternate the layer heights between .05 for the fiber layers and anywhere between .05 and ,2mm (depending on material and desired fiber density) for the solid matrix material layers. Then two 3D models that are just an array of lines are added as a modifier to the tensile bar part to act as the tool paths or "part" for the TLPC fibers and the matrix material that get printed next to TLPC on the same layer. For those two modifiers the correct materials are then selected in the slicer and the models are lined up properly in relation to the tensile bar model to create the composite layers.

[0049] In an aspect of the invention, polymer fibers are created in-situ within the desired article during the additive manufacturing process. Additional infill or layers can be incorporated into the article comprising the same material of the fiber or a second material selected for cost or for other reasons. Such additional infill or layers can be printed using conventional processes thus simplifying the manufacture.

[0050] In an aspect of the invention, discrete polymeric fibers are created in-situ in additive manufacturing which are encapsulated by a bulk or second polymer. The fibers provide strength to the bulk polymer and may consist of the same polymer as the bulk polymer. Although TLCP fibers provide significant advantages in strength, other materials can also be utilized in this method of printing a first molten continuous thermoplastic fiber from an additive printer in a first direction, and then a second and so on. As there is space between each fiber, each fiber can be encapsulated by the bulk polymer and the plurality of fibers provide strength in the first direction.

[0051] In an aspect, the discrete fibers can be printed in more than one direction thus providing strength in the second, third and other directions. In related aspect, the discrete fibers can be printed as a mesh of fibers extending in at least two directions with fiber extending in a first direction being printed first and then a second plurality of fibers being printed in a second direction and also onto the first plurality of first direction fibers.

[0052] Printing TLCP through an inexpensive and relatively quick printing process and make articles having high strength and include highly oriented linear crystalline polymer chains is further described in the following examples.

[0053] Example 1

[0054] Feedstock filament was prepared by first compounding and extruding a base TLCP. Pellets of the base TLCP were fed into a twin-screw compounding extruder through a feeding port using a volumetric pellet feeder. As the polymer melted and progressed along the barrel, it was conveyed by the twin screws. The homogenized melt exited the twin- screw extruder into a gear-type melt pump, which stabilized the flow and pressure. The melt was then extruded through a die or nozzle into a continuous strand resembling a large spaghetti strand. This strand was air-cooled and then fed into a rotary-knife pelletizer, which chopped it into pellets approximately 3 mm in diameter and 4 mm in lengthyielding the fully compounded TLCP formulation. The compounded pellets were reintroduced into the same twin-screw extruder, and the melt was conveyed through the system and extruded through a die to form 1.75 mm diameter filament. After air cooling, the filament was monitored using a laser micrometer to ensure dimensional accuracy and then wound onto plastic spools. The final product is spools of a 1.75 mm TLCP filament as used in FDM printers.

[0055] Example 2

[0056] Using the 1.75 mmTLCP filament in a FDM printer, rectilinear tensile bars were manufactured to demonstrate an aspect of the invention in a simple way. This aspect consists of multiple layers of extruded polymer bead laid down with a perimeter and an infill of beads in a rectilinear fashion as shown in FIG 1 & 2.

[0057] Multiple layers of a first polymer are built up using conventional but specific speeds (~1000 mm / min) of the extrudate at a specific melt temperature (~325°C). In this aspect the layers are ,05mm thick and the bead is ~.48mm wide x .05 thick. The printer's build plate or bed is at acertain temperature (~160 °C), and the nozzle is set at the desired temperature (60 °C). With these settings, a first solid layer is laid down just as indicated. In a comparative art example, multiple layers of the first polymer can be laid down in consecutive steps to yield the desire height of a comparative tensile bar.

[0058] In an aspect of the invention, the melt temperature, build plate temperature and the chamber temperature are the same as the comparative build. A first solid layer of thefirst polymer is laid down as described in the comparative example. However, instead of an identical second layer, the next layer is a fiber layer consisting of a single pass perimeter around the tensile bar with numerous fiber like beads creating the infill. The fibers bond to the previous layer below as shown in FIG 1A. The fiber like beads are extruded at a much higher speed (~4800 mm / min) as the infill and are about .100 mm in width x .050 mm in height. These fibers are spaced so that there is a narrow gap between them and they do not touch each other. The higher extrusion speed and smaller cross section create a fiber that is being drawn down in cross sectional area much like conventional fiber spinning with a resultant increase in tensile properties.

[0059] As shown in FIG IB (partial), the next layer is a solid full density layer of beads laid down just as the first layer. While this solid layer is being extruded at the lower speed (~1000 mm / min) it covers the fiber as shown in FIG 1C and also fills in the spaces between the fibers on the layer below. This part of the process encapsulates the fiber on the layer below.

[0060] The process continues by alternating solid layers and fiber layers until the part reaches the desired thickness as shown in FIGs ID, IE and IF. The solid top layer, the solid bottom layer, and the perimeters of each layer create a solid structure fully encapsulating and bonding to the fiber layers.

[0061] Further, cross-sections of the layered tensile bar are shown in FIGs 2A and 2B, with a perspective view in FIG 2C.

[0062] This process has shown to increase the tensile strength recorded during testing by multiple times relative the comparative example when TLCP is used to make the fibers and PLA is used as the first polymer.

[0063] Further strength can be incorporated by using TLCP as both the fiber and the first polymer. In this aspect, the strength and other physical properties are greatly enhanced.

[0064] In an aspect, the cross section of the TLCP fiber is not round but relatively flat relative to the surface it is laid upon. The aspect ratio of this flat fiber is greater than unity in that the width is greater than the height in cross-section, and this shape is distinctive of the surface tension of the material which is affected by the temperature of the nozzle and chamber into which the flat fiber is extruded into.

[0065] Testing of the samples is according to the ASTM standard ASTM D3039 - StandardTest Method for Tensile Properties of Polymer Matrix Composite Materials using ADMETeXpert 8000 Planar Biaxial Testing Systems. The roughly 1 x 4 x 90 mm and 1 x 6 x 90 mm rectilinear samples were crafted as larger samples were often too strong for the systems to handle as the load cells were not strong enough to break a larger bar.

[0066] Table 1 details the measured Tensile strength, Elongation and Youngs Modulus of prepared samples having 19 and 21wt% TLCP in PLA. Data relating to the comparative sample is also presented and comparative date is calculated.

[0067] The inclusion of the TLCP fibers creates significant strength advantages of 4.22 times that of the polymer article printed without the TLCP fibers.

[0068] Table 1Sample19%TLCP 21%TLCP 0%TLCP 100% TLCP

[0069] Example 3

[0070] When making films, since you are only drawing it from one direction the strength can be unidirectional. With TLPC being able to print at small layer heights, film like structures can be printed and the strength of the created film can be in whatever direction or directions desired; all depends on which direction the TLPC is laid down; very similar to a woven scrim. This is done on a high temperature printer with a flat glass build bed at 180C-200C and the fibers being created with the setting previously mentioned. 100-micron films have been produced this way repeatably up to the size of an A4. The main limiting factor is the tolerance and flatness of the glass bed and the 3D printing hotend gantry. Under 100-micron films can be manufactured, and such thicknesses can be added by calendaring the printed sheets. This technique acts to flatten out the film to a desired thickness and increase the interlayer adhesion between overlapping TLPC lines. The filmalso does not have to be just a solid sheet. It can have a pattern of holes / lines to make it easy to adhere between two other films.

[0071] TLPC exhibits properties that are unique to the other 3D printing polymers on the market. For tensile strength, Young's modulus, flexural strength, and flexural modulus there are no other polymers on the market that come close to its specs. This strength is achieved on a non-proprietary printer and without adding ex-situ manufactured continuous fibers into a polymer part. Even when printed fibers are not included in a part, TLPC exhibits tensile strength properties double that of part comprising unannealed PEEK.

[0072] TLPC can also be printed not just as plastic but as a continuous fiber on a standard 3D printer with no modifications and as a film. This allows the material to be printed as a matrix plastic and as a fiber to create a composite like parts all just by changing the print settings for infill to create fibers. You can also use it in situ with other 3D printing polymers to give parts more strength and rigidity. Usually, you would need a proprietary printer with a separate nozzle or system to lay continuous fibers to create a strong composite part. Those systems also have curvature and tool path limitations to lay the continuous fiber. TLPC does not have those limitations when creating fibers in a part.

[0073] The strength that TLPC achieves is also not limited to very expensive printers. It can be printed on high temperature printers to achieve very high tensile strengths, but it can also be printed on widely available printers that cost much less. This makes the material much more accessible and economical than other materials that are marketed as an engineering grade, high strength polymer.

[0074] Example 4

[0075] Due to TLPC's high thermal conductivity, compared to other polymers, it makes it a great material for material extrusion 3D printing. When getting pushed through a heated nozzle, the TLCP material heats up very quickly to its melting temperature to allow for good extrusion and a low likelihood of clogging. This is one of the characteristics of TLPC that allows it to print at small layer heights of ,05mm at fast speeds and even allows fiber printing with a ,2mm nozzle with ,05mm layer height at fast speeds. TLCP enables high printing speeds at a ,05mm layer height or with a ,2mm nozzle without clogging. High thermal conductivity also makes it cool rapidly once it is extruded into a part which helps the part maintain its shape and dimensions.

[0076] The rheology of TLPC allows TLPC to be printed with small layer heights and less that 0.3mm diameter nozzles for example: 0.2mm nozzles at fast speeds. It is a shear thinning fluid when melted which means it exhibits non-Newtonian behavior and its viscosity decreases under shear strain. When printing at smaller layer heights, smaller nozzles, and higher speeds all increase the shear strain which decreases TLPC's viscosity. A lower viscosity allows for better flowability of TLPC through a nozzle, while enabling the mesogen to align in the printing direction. Other popular printing materials also exhibit shear thinning but do not get viscous enough or have enough thermal conductivity to be able to print at small layer heights at high speed.

[0077] Increasing shear forces are good for TLPC because it aligns its molecular chains to produce crystalline fibers that exhibit great tensile and flexural mechanical properties. TLPC prints as a crystalline material on a standard printer with no extra post processing such as annealing.

[0078] Comparison of TLCP to other polymers used in additive manufacturing in detailed in Tables 2 and 3.

[0079] Table 2

[0080] Table 3

[0081] Example 5

[0082] The viscosity of a TLCP feedstock was modified by tuning the molecular weight via annealing, and several TLCP variants were synthesized in pellet form with different melt viscosities (Table 4). In this example the base TLCP was Vectra A950 from Celanese. Viscosity measurements were performed using a capillary rheometer at a shear rate of 1800 s-1and a melt temperature of 300°C. This achieved more than a twofold increase in viscosity— an important factor for enhancing FDM print control at elevated temperatures. The measured viscosities for each variant are shared in Table 4.

[0083] Table 4: Different viscosity TLCP variants

[0084] Variant Txl, which exhibited 15% higher viscosity than the base, was further processed into a standard 1.75 mm 3D filament using the method of Example 1. A spool of Txl filament was used in a 3DGence PEEK printer to produce test bars. An increase in interlayer adhesion was observed, rising from less than 10 MPa to 18 MPa. This enhanced viscosity allows operation at elevated temperatures and improved overall adhesion.

[0085] Example 6

[0086] Isothermal DSC studies were used to assess the crystallization kinetics of TLCP at temperatures approaching the melting transition. Samples were first heated above their melting point to erase any thermal history, then rapidly cooled to a target temperature and held isothermally for 20 minutes to achieve full crystallization. The material was then reheated above the melting point and quenched again. This heating-cooling-holding cycle was repeated at isothermal temperatures from 310 °C down to 200 °C, with the crystallization enthalpy recorded at each temperature.

[0087] The inverse half-crystallization time (l / rso%), which is the inverse of the time that the polymeric materials require during an isothermal process to reach 50% of their relative crystallinity, was evaluated using the Avrami equation (Eq. 1), where n, k, and Vc(t) represent the Avrami exponent, growth constant, and the relative transformed fraction by volume into the semicrystalline state, respectively. From this, the half-crystallization time was calculated using Eq. 2.1 - Vc(t - to) = exp[ ^(Z - Zo)"] (1) ln(0.5) 1 / / T5O% = k (2)

[0088] FIG 3A shows Conventional Heat-cool-heat isothermal DSC plot indicating the relevant thermal transitions, and FIG 3B shows l / t50% as a function of various isothermal holding temperatures for the crystallization growth kinetics (TO denotes the starting temperature to which the molten LCP was isothermally quenched to). Building on the isothermal crystallization kinetics shown in FIG 3B, TLCP demonstrates an unusually early onset of crystallization. Notably, even when quenched to temperatures several degrees above its melting transition (as seen in the melting curve in FIG 3A), measurable molecular ordering and crystal growth still occur. The elevated inverse half-crystallization rates (l / rso%) at these high temperatures indicate that the mesogenic segments in the melt remain sufficiently aligned to initiate crystallization without the deep undercooling typically required for semicrystalline thermoplastics. This behavior, referred to as "meltstate" crystallization, stems from the inherent liquid-crystalline architecture of the polymer. The mesogen units and their retained orientation in the molten state substantially reduce the free-energy barrier for crystal domain formation. Consequently, processing parameters— such as extrusion and nozzle shear rates, which promote segmental alignment, as well as rapid quenching, which preserves this nascent order— have a profound impact on the resulting crystallinity. These factors, in turn, directly influence the tensile modulus and strength of the printed material. This mechanism stands in stark contrast to conventional polymers like PEEK, where crystallization is limited to the solidification front and follows a classical Avrami-type behavior only below the melting temperature. In TLCP, the continuous, orientation-driven crystallization offers a uniqueopportunity to tune mechanical performance through careful control of thermal and mechanical processing conditions.

[0089] During FDM printing, TLCP is deposited as beads of varying thickness under elevated temperature and high shear. This combination of heat and flow forces the polymer chains into alignment, promoting crystalline ordering even before solidification. As the material cools, the induced orientation and crystallinity become locked in, directly dictating the part's mechanical performance.

[0090] Example 7

[0091] In this example, fibers were extruded under various processing conditions, and their cross-sections were analyzed via wide-angle X-ray scattering (WAXS) to examine crystal orientation and morphological differences. For transmission-mode X-ray analysis, a small specimen (thickness i 0.3 mm) was sectioned from a 3D printed plaque using a bandsaw. Micrographs revealed a pronounced skin-core morphology, attributed to the material's low heat of fusion and rapid surface quenching.

[0092] WAXS measurements were conducted using a Bruker D8 Venture system equipped with a CuKa radiation source ( = 1.54 A) and a three-module Pilatus 300 detector. The instrument was calibrated” with silver behenate, and specimens were mounted orthogonally to the beam with their long axis perpendicular to the X-ray path. A fixed sample-to-detector distance of 101.4 mm was used. The resulting diffraction patterns showed distinct peaks at 217 = 11.2°, 14.9°, 16.5°, 20.1°, 22.2°, and 26.4°, with the most intense scattering observed at 217 = 20.1°. This peak was used for comparative analysis of crystal sizes, which were consistently larger in extruded fibers— both in the skin and core regions— than in 3D-printed specimens.

[0093] Azimuthal integration revealed enhanced molecular alignment in the 3D-printed plaque, as indicated bya more negative Herman's orientation parameter (f = -0.31), compared to extruded fibers processed via two different methods (f= -0.25 and / = -0.18, respectively). A value approaching -0.5 signifies orientation perpendicular to the extrusion direction. This pronounced orientation in printed parts is attributed to the cold-bed deposition and rapid quenching, which inhibit chain relaxation and preserve residual stresses. In contrast, extrusion allows longer residence times in the heated die, enabling greater molecular reorganization.

[0094] Mechanically, extruded fibers achieved tensile strengths ranging from 1.3 to 1.5 GPa, while 3D-printed samples, not including any fibers, reached a maximum of approximately 0.5 GPa. This discrepancy is attributed to differences in melt-state alignment and cooling profiles: extrusion imparts strong shear and gradual cooling, promoting the growth of larger, more aligned crystalline domains. Conversely, the layer-by-layer deposition in additive manufacturing favors finer crystals due to its rapid solidification.

[0095] Example 8

[0096] In this Example, the effects of TLCP fiber (i) layer height, (ii) print head speed, and (iii) print head temperature were investigated. Specimens were fabricated using ASTM D3039 geometry— a standard commonly used to evaluate composite materials. This test setup enabled direct benchmarking against advanced multi-material FDM approaches, including the Markforged continuous fiber reinforcement technique. All specimens were loaded in a ASTM D3039 universal testing machine in the Z-direction to directly measure interlayer adhesion strength, isolating the effect of process parameters on layer bonding performance.

[0097] A first set of experiments was conducted to investigate the influence of extrusion temperature on interlayer bonding. All specimens were printed using a fixed layer height of 0.2 mm and the "Very Fast" speed profile. A total of sixteen tensile specimens were fabricated at extrusion temperatures ranging from 315 °C to 350 °C, in 5 °C increments (See FIG 4.).

[0098] A clear trend emerged: Z-direction tensile strength increased linearly from 335 °C to 350 °C, reaching a peak of 13 MPa. This behavior supports the hypothesis that elevated interfacial temperatures— resulting from hotter extrudate— enhance interlayer bonding. Specifically, molten TLCP at higher extrusion temperatures transfers more heat to the underlying layer, leading to a higher surface energy and activation of secondary bonds.

[0099] These findings reinforce the conclusion that heat transfer— both during deposition and post-extrusion— is the dominant factor governing Z-axis strength in 3D-printed TLCP parts.

[0100] Further, TLCP samples were fabricated at four different layer heights: 0.08 mm, 0.12 mm, 0.16 mm, and 0.20 mm. Two samples were made for each condition, for a total sample size of 8 and printed at 350 °C.

[0101] Referring to FIG 5, the results showed a positive correlation layer height and Z- strength. The lowest Z-axis strength was observed for the bar printed with 0.08 mm layer height (4.5 MPa), while the highest was observed with the bar printed with 0.20 mm layer height (10.0 MPa). This trend suggests that thinner layers may not provide sufficient thermal mass to adequately conduct heat into previously deposited layer, resulting in weaker diffusion and bonding across interfaces. Conversely, thicker layers retain more heat and may dwell longer at elevated temperatures near the nozzle, improving the interfacial temperature gradient and facilitating stronger interlayer fusion. These findings support the hypothesis that layer height directly affects the thermal and geometric conditions necessary for strong interlayer adhesion in TLCP, and they serve as a foundation for further parameter tuning.

[0102] Finally, to assess the time scales required for optimal interlayer bonding, we investigated the impact of print speed on Z-direction tensile strength. Building upon previous results— which identified a 0.2 mm layer height and 350°C nozzle temperature as optimal— we fixed the layer height at 0.2 mm and used a nozzle temperature of 350°C. Eight specimens were printed using five distinct average speed profiles: Ultra Slow, Slow, Mid, Fast, and Ultra Fast (ranging from infill speeds of 50 mm / s to 500 mm / s, with 90 mm / s increments).

[0103] Tensile strengths were again measured using ASTM D3039 geometry and standards. Referring to FIG 6, faster print speeds initially correlated with increased Z-direction strength, likely due to reduced cooling times and elevated interfacial temperatures that enhanced diffusion-based bonding between layers . However, the "Ultra Fast" seting resulted in a notable decline in strength, suggesting that excessively rapid printing compromises bonding quality. These results indicate the existence of an optimal speed range, between about 275 and 440 mm / s whereimproved heat retention facilitates interlayer adhesion— but beyond which insufficient material contact time or incomplete fusion reduces performance.

[0104] Additionally, it was observed that high thermal conductivity nozzles (above 390 to 401 W / (m-K; e.g., copper or diamond-coated) significantly improve interlayer adhesion, especially below 340 °C. Hardened steel nozzles, while wear resistant have lower thermal conductivity and limit heat transfer to prior layers and result in weaker Z-bonds.

[0105] Example 9

[0106] This example was conducted to assess whether thermal annealing under Z-axis pressure could improve the strength of 3D-printed components. To prevent deformation during annealing, printed test bars were embedded in supporting matrices having a smooth surface because the support structure can imprint deformation at higher temperatures.

[0107] Annealing a Z-bar specimen at 300°C under Z-directional pressure increased its maximum stress from 3 MPa (untreated) to 10 MPa. At 330 °C, partial melting of the material was observed, however the remaining bar— although thinner— exhibited increased strength. The highest strength value recorded using this method was 35 MPa, representing a twelvefold improvement over the untreated sample, despite some voids visible in cross-section microscopy.

[0108] Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

Claims

CLAIMSWhat is claimed is:

1. A thermotropic polymer article, created by an extrusion process, which includes discrete continuous polymer fibers which are encapsulated by a bulk polymer, wherein the continuous fiber and the bulk polymer are melt processable and wherein the polymer fiber is created during the extrusion process.

2. The article of claim 1, where the polymerfibers comprise PEEK, thermoplastic liquid crystal polymer, Nylon, or any other polymer that can be extruded as a continuous polymer fiber.

3. The article of claim 1, wherein the polymer fiber comprises thermoplastic liquid crystal polymer.

4. The article of claim 3, wherein the bulk polymer comprises thermoplastic liquid crystal polymer.

5. The article of claim 1, wherein the polymer fiber comprises thermoplastic liquid crystal polymer, and the thermoplastic liquid crystal polymer comprises a hydroxybenzoic acid repeat unit.

6. The article of claim 1, wherein the polymer fiber comprises thermoplastic liquid crystal polymer, and the thermoplastic liquid crystal polymer comprises a hydroxynaphthoic acid repeat unit.

7. The article of any one of claims 1 to 6, wherein the extrusion process is an additive printing process.

8. The article of any one of claims 1 to 6, where the polymer fiber can be melt processed at or less than 350C.

9. The article of claim 2, where the fibers are extruded into a chamber the temperature of which is less than 80C and greater than 25C.

10. The article of any one of claims 1 to 6, wherein the polymer fibers extend in a first direction, and the tensile strength of the article is greater than 200 MPa in the first direction.

11. The article of any one of claims 1 to 6, where the Young's modulus of the article is greater than 10 GPa.

12. The article of any one of claims 1 to 6, wherein the fiber is comprised of a thermotropic mesogen.

13. The article of any one of claims 1 to 6, wherein the extrusion process creates the article by laying down polymer in layers, and wherein the polymer fibers are created on distinct layers.

14. The article of any one of claims 1 to 6, wherein the extrusion process creates the article by laying down polymer in planar layers, wherein a plurality of the polymer fibers are created on distinct layers and extend throughout the distinct layers, and thermoplastic liquid crystal polymer is dispersed throughout the article and bonded to the fibers.

15. The article of claim 14, wherein the extrusion process is an additive printing process performed with at least one extrusion nozzle, and wherein the extrusion nozzle has an internal diameter equal to or less than 0.2 mm, wherein the extrusion nozzle extrudes the polymer at a temperature between 335C and 350C, and wherein the extrusion nozzle extrudes the polymer at a rate between 275 and 440 mm / s.

16. The article of any one of claims 1 to 6, wherein the polymer fibers are aligned in a parallel direction.

17. The article of any one of claims 1 to 6, wherein the viscosity of the polymer fibers when it is molten is greater than 27 Pa.s.

18. The article of any one of claims 1 to 6, wherein a portion of the polymer fibers are aligned in a first direction, and a second portion of the polymer fibers are aligned in a second direction.

19. The article of any one of claims 1 to 6, wherein the polymer fibers are arranged in a mesh.

20. A process for forming a polymer article comprising TLCP and a second polymer having the following steps: a) depositing a plurality of molten TLCP droplets to form a plurality of TLCP fibers, wherein (at least one) fiber extend parallel to another fiber but is not adhered thereto ; b) depositing a plurality of molten TLCP droplets to form at least one planar structure extending parallel to said TLCP fibers and adhered to adjacent TLCP fibers; and c) depositing a plurality of molten droplets of the second polymer so that they may adhere to deposited TLCP fibers and planar structures.

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