Green continuous preparation process of chemical modification reinforced composite material

Abstract

The invention discloses a chemical modification reinforced composite material green continuous preparation technology, and relates to the technical field of composite material preparation, and the chemical modification reinforced composite material green continuous preparation technology comprises the following steps: carrying out mechanical grading and drying on reinforced fibers or water-containing pasty alkaline residues; the method comprises the following steps: carrying out water-phase enzymatic pretreatment on fibers or water-containing pasty alkaline residues in a continuous flow contactor; performing on-line activation on the fiber or the water-containing pasty alkaline residue through atmospheric pressure plasma or corona; performing continuous coating size treatment on the fibers or the water-containing pasty alkaline residues; continuously adding a thermoplastic matrix material, a grafting monomer or a grafting auxiliary agent and a nano reinforcing agent into a double-screw reactive extruder, and carrying out reactive extrusion; and feeding the functional fibers into a vacuum impregnation tank in a directional laying or continuous winding manner. According to the method, traditional organic solvent dipping or high-energy chemical etching is replaced by enzymatic aqueous phase pretreatment and atmospheric pressure plasma synergistic surface activation, so that solvent residue and high energy consumption are avoided, and meanwhile, the surface chemical reaction site density of the fiber water-containing pasty alkaline residues is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, specifically to a green and continuous preparation process for chemically modified and reinforced composite materials. Background Technology

[0002] Current composite material production primarily relies on intermittent, batch, or simple continuous mixing processes, and common technical problems include: poor wetting and adhesion at the interface between fibers, aqueous alkaline residue, and the matrix (leading to fiber pull-out and low mechanical properties); surface modification steps often depend on organic solvents or high-energy-consuming processes (which are environmentally unfriendly); nano-reinforcing phases tend to agglomerate in the melt and are difficult to disperse uniformly; impregnation and degassing processes are inefficient, resulting in high porosity and defect rates; and insufficient process control methods lead to significant batch-to-batch fluctuations and high energy consumption. These problems limit the large-scale, continuous industrial application and green transformation of natural and recycled fibers and functional nanophases.

[0003] Patent CN116376543B discloses a silane-functionalized carbon dot-based multicolor room temperature phosphorescent composite material, its preparation method and application. The above patent enables the composite powder to emit multicolor room temperature phosphorescence at different excitation wavelengths.

[0004] The aforementioned patents have produced composite materials that exhibit multicolor phosphorescence under multi-wavelength excitation and some composite materials that exhibit room-temperature phosphorescence properties that change over time. These materials have potential application value in fields such as anti-counterfeiting and advanced information encryption. However, traditional organic solvent impregnation or high-energy chemical etching suffer from solvent residue and high energy consumption.

[0005] To this end, this application proposes a green and continuous preparation process for chemically modified and enhanced composite materials that avoids solvent residue by replacing traditional organic solvent impregnation with enzymatic aqueous pretreatment and atmospheric pressure plasma synergistic surface activation. Summary of the Invention

[0006] The purpose of this invention is to provide a green and continuous preparation process for chemically modified and reinforced composite materials, in order to solve the technical problems mentioned in the background art, such as poor wetting and bonding at the interface between fibers, water-containing paste-like alkaline slag and the matrix; the fact that the surface modification steps mostly rely on organic solvents or high-energy-consuming treatments; the tendency of nano-reinforcing phases to agglomerate in the melt and be difficult to disperse uniformly; the low efficiency, high porosity and defect rate of the impregnation and degassing processes; and the lack of production process control methods, batch-to-batch fluctuations and large energy consumption.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a green and continuous preparation process for chemically modified and reinforced composite materials, wherein the preparation process is performed sequentially and includes the following steps: A. Mechanically classify and dry the reinforcing fibers or water-containing paste-like alkali residue; B. The fiber or water-containing paste-like alkaline residue obtained in step A is subjected to aqueous enzymatic pretreatment in a continuous flow contactor; C. The fiber or aqueous paste-like alkaline residue obtained in step B is activated online by atmospheric pressure plasma or corona discharge; D. The fiber or water-containing paste-like alkaline residue obtained in step C is subjected to continuous coating size treatment. The coating method is one of spraying, dipping or scraping. The subsequent drying is ventilated belt drying. E. The thermoplastic matrix material, grafted monomers or grafting aids and nano-reinforcing agents are continuously added into a twin-screw reactive extruder and reactive extrusion is carried out; F. The functionalized fibers processed in step D are fed into the vacuum impregnation tank by directional laying or continuous winding, while ultrasonic or high-frequency vibration is applied in the impregnation section. G. The impregnated strip is degassed and shaped by continuous calendering or vacuum roll pressing. H. A hybrid infrared and microwave heating device is used to cure the strip for a short time in the later stage of calendering; I. Set up an online detection unit on the production line. The detection unit is connected to a programmable controller to record and output detection signals; J. Cool, cut or wind the strip obtained after step H.

[0008] Preferably, the mechanical grading is performed with a sieve aperture of 0.05-5.0 mm, the drying is carried out using a continuous belt dryer or a fluidized bed dryer, the drying temperature is 60-120℃, and the residual moisture content is ≤2.0 wt%.

[0009] Preferably, the enzyme used in the enzymatic pretreatment is selected from cellulase, pectinase, xylanase or a mixture of two or more, the enzyme dosage is 0.01-1.0 wt% based on solid mass, the reaction temperature is 30-60℃, the pH value is 4.5-8.0, and the residence time in the continuous reactor is 10-240 s; The continuous flow contactor is a series static mixer or a disc reactor. The liquid-to-solid volume ratio of the enzyme solution to the fiber is 5:1-50:1, and it is equipped with an online pH adjustment device to maintain the pH within the set range.

[0010] Preferably, the plasma processing gas is air, oxygen, nitrogen, or a mixture thereof, and the processing power density is 0.01-10 W / cm³. 2 The processing linear velocity is 0.1-10 m / min; The plasma device includes a gas gap discharge unit formed by at least one pair of parallel electrodes, a gas flow rate of 0.1-10 L / min·cm amplitude, a processing voltage of 1-20 kV, and a processing frequency of 10-100 kHz.

[0011] Preferably, the coating size treatment uses one of the following: an aqueous silane emulsion, a polymeric multifunctional grafting agent, or a bio-based polymer emulsion; the coating solid content is 1.0-8.0 wt%; the drying temperature is 50-120°C; and the residual solvent is ≤0.5 wt%. The aqueous silane emulsion consists of 5-50 wt% silane coupling agent, 1-20 wt% film-forming aid, water, and dispersant, with a viscosity of 50-500 mPa·s. After spraying or impregnation, the solid content is brought to the target value through an infrared pre-drying section.

[0012] Preferably, the matrix material is selected from PLA, PP, PE, or recycled materials of the above materials; the temperature gradient in the extrusion section is 120-250℃; the screw speed is 100-600 rpm; the amount of grafting agent is 0.2-5.0 wt% of the matrix mass; and the amount of nano-reinforcing agent is 0.1-8.0 wt% of the matrix mass. The twin-screw reactive extruder uses a parallel interlocking twin-screw design. The barrel is divided into at least six temperature zones: the first zone is 120-160℃, the middle zone is 150-220℃, and the tail zone is 160-250℃. The feed ratio is matrix:grafting agent:nano-reinforcing agent = 100:(0.2-5.0):(0.1-8.0). The extruder is equipped with a side inlet for adding nano-reinforcing agents and a high-shear dispersion section.

[0013] Preferably, the vacuum impregnation tank has a vacuum degree of 5-50 kPa, a relative impregnation speed of 0.05-2.0 m / min, an ultrasonic frequency of 20-40 kHz, and an ultrasonic power density of 0.1-5.0 W / cm³. 2 ; The vacuum impregnation tank has a multi-stage vacuum partition structure, including an inlet preheating zone, an impregnation main tank, and a degassing zone. An ultrasonic transmitter and electrode pair are installed in the impregnation main tank. The maximum voltage of the electrode pair is 50kV, and the electrode frequency is 1-100kHz.

[0014] Preferably, the vacuum rolling section includes an upper roller and a lower roller, the surface temperature of the upper roller is controlled at 80-220℃, the surface temperature of the lower roller is controlled at 60-200℃, the roller gap is adjustable in the range of 0.01-5.0mm, and a vacuum degassing chamber is set after rolling, the vacuum degree of the degassing chamber is 1-50kPa; The working pressure of the calendering roll is 0.1-5.0 MPa, and the linear speed is 0.05-3.0 m / min.

[0015] Preferably, the detection unit includes a near-infrared spectrometer (NIR), an ultrasonic detection probe, a thickness sensor, and a high-speed imaging camera; The near-infrared spectrometer (NIR) measures wavelengths from 700 to 2500 nm and has a sampling frequency of 1 to 50 Hz; the ultrasonic testing probe has a center frequency of 0.5 to 10 MHz and a sampling frequency of 1 to 10 kHz; the thickness sensor has a resolution of ≤10 μm; the high-speed imaging camera has a frame rate of 100 to 5000 fps; and the programmable controller is a PLC or industrial computer with at least 8 analog inputs and 16 digital input / output interfaces.

[0016] Preferably, the microwave and infrared hybrid heating device comprises an infrared radiation unit and an industrial microwave cavity arranged side-by-side within the same curing section. The microwave cavity frequency is either 915MHz or 2.45GHz, the continuous power of the microwave cavity is 0.1-50kW, and the radiation power density of the infrared unit is 0.1-5.0kW / m². 2 The curing section is equipped with no fewer than three temperature sensors for temperature acquisition and output to the control bus; The cooling temperature is 5-60℃, and the winding tension is 0.1-5.0 N / cm.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention replaces traditional organic solvent impregnation or high-energy chemical etching by synergistic surface activation through enzymatic aqueous pretreatment and atmospheric pressure plasma, avoiding solvent residue and high energy consumption. At the same time, it significantly increases the density of chemical reaction sites on the surface of fiber-containing water-containing paste-like alkaline residue, which is conducive to subsequent grafting, enhances the fiber-matrix interface bonding and durability, and meets the requirements of green production. 2. This invention uses in-situ grafting reactive extrusion coupling to avoid separate grafting or solvent treatment steps between processes, reducing process steps and solvent usage, solving the problems of weak interface connection and moisture degradation caused by traditional physical bonding, forming a stable chemical interface, and significantly improving mechanical properties such as tensile, bending, and shear properties as well as resistance to humid heat aging. 3. This invention overcomes the problems of mechanical attenuation and defects caused by agglomeration, uneven impregnation, and internal pores in nano-water-containing paste-like alkaline slag by vacuum impregnation combined with ultrasonic electrostatic assistance for highly uniform nano-phase dispersion and non-porous wetting. It reduces the void ratio, improves the uniformity and functionality of the material, improves fracture toughness and fatigue life, and enhances the consistency of the product. 4. This invention solves the problem of unstable product performance and high scrap rate caused by batch fluctuations in raw materials during continuous production by using multimodal online detection and adaptive closed-loop process control. It reduces manual intervention and rework, significantly reduces defect rate, improves batch consistency and optimizes energy consumption. Attached Figure Description

[0018] Figure 1 This is a schematic diagram comparing the tensile strength and modulus of the present invention; Figure 2 This is a schematic diagram of the water absorption curve over time according to the present invention; Figure 3 This is a schematic diagram of the simulated thermogravimetric curve of the present invention; Figure 4 This is a schematic diagram of the simulated spectrum of the present invention; Figure 5 This is a histogram of the void ratio distribution of the present invention; Figure 6 This is a schematic diagram of the process thickness timing curve of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 Please see Figures 1-6 A green and continuous preparation process for chemically modified and reinforced composite materials, using PLA matrix + chopped hemp fiber + nanocellulose, for lightweight sheet materials: Material: Reinforcing fiber: chopped hemp fiber, sieved to 0.5-2.0mm; Matrix: Recycled or commercial polylactic acid (PLA); Grafting agent: Maleic anhydride grafted onto PLA (or grafted in situ in the extrusion section). Nano-reinforcing agent: Nanocellulose CNF, added at 0.5 wt% (relative to matrix mass); Size enhancer: Water-based silane emulsion (dry basis solids content 3wt% relative to fiber weight); Enzyme: Cellulase, enzyme amount 0.1 wt% (relative to the mass of fiber solids).

[0021] equipment: Continuous flow static mixer (enzyme-catalyzed section), dedicated atmospheric pressure plasma roller treatment unit, continuous spraying and impregnation and belt drying line, parallel interlocking twin-screw reactive extruder (6 temperature zones, side feed port), vacuum multi-stage impregnation tank (with ultrasonic), vacuum roller pressing section, infrared + microwave combined curing section, online NIR, ultrasonic, thickness detection unit, PLC control system.

[0022] Process steps and parameters: Screening and drying: Vibrating screen to 0.5-2.0mm, belt dryer at 80℃ until fiber moisture content ≤2wt%; Enzymatic pretreatment (continuous): Cellulose and cellulase aqueous solution were contacted in a static mixer at a liquid-solid ratio of 10:1 for 60 seconds at a temperature of 40℃ and a pH of 6. Plasma treatment: Enzyme-treated fibers are passed through a plasma roller with a power density of 1 W / cm². 2 The linear velocity is 1 m / min, and the gas being processed is air. Dimensional coating and drying: The aqueous silane emulsion was applied by spraying, with a dry basis of 3wt%, followed by belt infrared pre-drying at 70℃, leaving residual water ≤0.5wt%. Raw material ratio and reactive extrusion: PLA: grafting agent MAH is fed at a ratio of 100:1 (mass ratio), CNF 0.5wt% is added through the side feed port; extrusion temperature range 170 / 185 / 190 / 180 / 170 / 160℃, screw speed 300rpm, high shear dispersion section is set; Vacuum impregnation: Functionalized fibers are oriented and laid into a multi-stage vacuum impregnation tank at a vacuum level of 20 kPa and an impregnation linear velocity of 0.5 m / min, while simultaneously being ultrasonicated at 30 kHz and a power density of 0.5 W / cm². 2 ; Degassing and calendering: Vacuum roll pressing, roll temperature 120℃, working pressure 1MPa, linear speed 0.5m / min, roll gap 0.3mm; Combined curing: Infrared power density 0.5kW / m 2 Microwave cavity 2.45GHz, power 0.5kW, total curing time 5min; Online inspection and winding: NIR (sampling frequency 5Hz), ultrasonic detection of voids, thickness sensor resolution 10μm, finished product thickness 0.8-2.0mm, winding after cooling to 25℃, tension 1N / cm.

[0023] Enzymatic aqueous pretreatment coupled with plasma generates high-density active sites, which, in conjunction with aqueous silane, form a stable chemical size layer. In-situ grafting of the matrix is ​​achieved through twin-screw reactive extrusion, forming a chemically bonded interface. The interfacial adhesion is significantly enhanced, and the structural stability of the prepared sheet under humid heat aging conditions is significantly improved compared with that of the dry sample. Nanocellulose is uniformly distributed through side feeding and high shear dispersion, improving fracture toughness and microstructure homogeneity.

[0024] Implementation 2 Please see Figures 1-6 A green and continuous preparation process for chemically modified and reinforced composite materials, using recycled PP matrix + chopped glass fiber + nano-clay, for use in structural panels: Material: Reinforcing material: Short-cut glass fiber (1-4mm in length); Matrix: Recycled polypropylene (rPP); Grafting agent: Maleic anhydride grafted onto PP (or in-situ grafting during extrusion, 2wt%). Nano-hydrated alkaline paste residue: layered nano-clay MMT, added at 2.0 wt%; Size-enhancing agent: Water-based silane-amine copolymer emulsion, solid content 4wt%.

[0025] Equipment and special features: twin-screw parallel interlocking extruder (6+ sections), fiber plasma corona processor, side-feed nano-water-containing alkali residue high-pressure pump, vacuum impregnation tank (electrode electrostatic assistance), online melt temperature and torque monitoring.

[0026] Process steps and parameters: Sieving and drying: sieve the fiberglass to 1-4mm and dry at 100℃ until the moisture content is ≤0.1wt%. Plasma treatment: glass fiber corona treatment, voltage 10kV, frequency 20kHz, line speed 2m / min; Size coating and drying: Water-based silane-amine copolymer emulsion spraying, dry base 4wt%, infrared pre-drying 90℃; Reactive extrusion: rPP:MAH (side-added) mass ratio 100:2, nano clay is added first in masterbatch form (50% MMT masterbatch) through side feed port, screw speed 350rpm, temperature range 180 / 210 / 220 / 210 / 190 / 170℃; Vacuum impregnation and electrostatic assistance: The impregnation tank is under vacuum of 15 kPa and the impregnation speed is 1.0 m / min; an electrostatic field (maximum voltage between electrode pairs of 10 kV) is applied in the impregnation section to promote resin penetration into the fiber gaps and inhibit the agglomeration of the nano-clay layer. Calendering and curing: Roller temperature 180℃, pressure 2MPa, linear speed 1.0m / min, short-time heating using microwave combined with infrared 1kW / m 2 Total curing time: 3-8 minutes; Online monitoring: NIR, melt temperature, and extrusion torque are monitored, and the data is recorded and archived on the production line.

[0027] Recycled PP is grafted with maleic anhydride in situ and combined with plasma-silane-sized glass fiber to achieve chemical compatibility between recycled resin and glass fiber; electrostatic field and vacuum impregnation are used in synergy to achieve delamination and uniform dispersion of nano-clay in the melt; high content of recycled material is allowed to participate in the preparation of structural components without sacrificing interfacial strength, ensuring the dimensional stability and flexural modulus of the board, and the nano-clay improves flame retardancy and maintains rigidity.

[0028] Implementation 3 Please see Figures 1-6 A green and continuous preparation process for chemically modified and reinforced composite materials, using a PE matrix + continuous basalt fiber + polymer emulsion, for extruded profiles: Material: Reinforcement: Continuous basalt fiber bundles (bundle diameter matched to equipment); Matrix: High-density polyethylene (HDPE); Grafting scheme: Grafting with peroxide-initiated methacrylic acid comonomers in the extrusion section (by side-addition of monomers and initiators), with a total grafting agent amount of 0.5-2.0 wt%; Size-enhancing agent: Aqueous emulsion of polyurethane dispersion (PUD), 2-5 wt% on dry basis.

[0029] Equipment and parameters: The parallel twin-screw extruder features a side-mounted monomer inlet, an online melt mixing and high-pressure mixer, a continuous filament impregnation line (with tension control), a vacuum degassing chamber, a die profile drawing and cooling line, and a microwave + induction combined heating section.

[0030] Process steps: Fiber pretreatment: Basalt fiber bundles undergo surface activation on a plasma roller at a power of 0.5 W / cm. 2 Linear speed: 0.8 m / min; Size coating: PUD is applied by scraping, 3 wt% dry basis, dried at 60°C; Extrusion and in-situ grafting: HDPE is fed into the main feed section of the extruder, and methacrylate monomers (MAA or GMA type) and peroxide initiators (benzoyl peroxide or other commonly used industrial initiators) are added to the side inlet. The temperature range is 150-220℃, the screw speed is 200-450rpm, and the reaction section is kept warm to complete the grafting. Continuous impregnation: Functionalized basalt fibers come into contact with melt-grafted PE through the impregnation section, and air is removed in the vacuum degassing zone. The impregnation speed is 0.2-1.0 m / min. Forming and Cooling: After the profile is demolded, it is drawn and cured in a cooling tank. The drawing rate is controlled in conjunction with the mold temperature. Online inspection: thickness and surface defect inspection.

[0031] For basalt fibers, which are difficult to chemically bond with PE, an in-situ grafting technique in the melt (initiated grafting) combined with a polyurethane dispersion size adjustment is employed to improve the likelihood of interfacial chemical bonding and wettability. This process is suitable for continuous extrusion production of profiles. The probability of interfacial debonding in the profiles decreases, dimensional stability is improved, and it is suitable for large-scale continuous extrusion production.

[0032] Implementation 4 Please see Figures 1-6 A green and continuous preparation process for chemically modified and reinforced composite materials, using a PLA matrix + oriented carbon nanotubes, a graphene oxide mixed phase + glass fiber, to prepare functional conductive and shielding sheets: Material: Reinforcement: 1-2mm chopped glass fiber (main carrier phase) and a small amount of conductive phase (0.5wt% graphene oxide (GO) + 0.5wt% short CNTs). Matrix: PLA; Grafting and dispersing aids: water-based polymer grafting emulsion + polar surface activation layer (plasma).

[0033] Equipment: Ultrasonic melt mixing section (twin screw with ultrasonic module), electrostatic field directional impregnation section (can generate a constant electrostatic field on both sides of the impregnation tank to conduct the conductive phase in a directional manner), vacuum degassing, infrared + microwave short-time curing.

[0034] Process steps: Fiber and conductive phase pretreatment: glass fiber plasma treatment; GO and CNT are first ultrasonically pre-dispersed in an aqueous dispersion (20kHz, 10min) to prepare a 10% masterbatch, which is then dried or fed into the side feed as wet masterbatch. Reactive extrusion: PLA main feed, grafting agent 1wt%, conductive phase 1.0wt% (0.5GO + 0.5CNT) added via side port in masterbatch form, screw speed 320rpm, temperature range 170-200℃, ultrasonic melt further breaks up agglomerates; Directional impregnation and electrostatic orientation: Functionalized glass fibers are laid in an oriented manner through an impregnation tank. During impregnation, an electrostatic field (5-10kV) is applied between the tanks to cause the conductive phase to arrange between the fibers and form a network, thereby improving conductivity. The vacuum degree is 20kPa and the linear speed is 0.4m / min. Rolling, curing and testing: Rolling temperature 130℃, rolling pressure 1MPa, infrared + microwave curing for 5-10 minutes, online measurement of surface resistivity and thickness.

[0035] In continuous production, a dual approach of electrostatic field and ultrasonic melt assistance is employed to achieve the directional alignment and uniform dispersion of the nano-conductive phase in the macroscopic direction, forming a compatible interface with functionalized fibers. The resulting sheets achieve low surface resistivity while retaining structural strength within a limited content range, making them suitable for shielding, conductive contact, or sensing substrates.

[0036] Implementation 5 Please see Figures 1-6 A green and continuous preparation process for chemically modified and reinforced composite materials, using PHBV bio-based polymer matrix + jute fiber + deep eutectic solvent DES as a green grafting agent: Materials and Green Media: Matrix: Poly(3-hydroxybutyric acid-co-3-hydroxyvalerate) (PHBV) or other bio-based polymers; Reinforcement: Jute short fibers 0.5-2.0mm; Grafting aid: Deep eutectic solvent DES, with an example combination of choline chloride: glycerol (molar ratio 1:2), used as a green grafting and surface modification medium carrying a small amount of bio-based multifunctional grafting monomers (0.5-2wt%). Nanophase: No or trace amounts of nanocellulose 0.2-1 wt%.

[0037] Equipment: Continuous flow contactor (for DES impregnation and recovery), plasma treatment, twin-screw reactive extruder, belt vacuum impregnation and short-time curing section, solvent recovery unit.

[0038] Process steps: Screening and drying: Jute fiber is dried to ≤2wt%; DES Impregnation (Continuous): The fiber is impregnated for 30-120 seconds with choline chloride:glycerol DES (containing 1 wt% of grafted monomer) through a continuous flow contactor at a temperature of 40-60℃ (low temperature) and then most of the DES is recovered through a dehumidification section (recovery rate ≥90%). Plasma treatment: After DES treatment, atmospheric pressure plasma is used to introduce more active groups; Reactive extrusion: PHBV and grafting agent are mixed and extruded in a twin-screw extruder at a temperature range of 140-190℃ and a screw speed of 200-350rpm. The grafting agent reacts further with the functional groups of the fiber in the melt. Impregnation and calendering: Vacuum impregnation tank vacuum 15-25kPa, linear speed 0.3-0.8m / min, calendering roll temperature 100-160℃, pressure 0.5-2.0MPa; Solidification and recycling: After short-term solidification, DES and waterborne emissions are collected and recycled for centralized treatment and reuse.

[0039] Using DES as a green, low-volatility grafting and mass transfer grafting agent to replace volatile organic solvents, combined with low-temperature enzymatic or plasma activation, reduces environmental impact and energy consumption; DES can be recycled during the process. The grafting efficiency between bio-based resins and natural fibers is improved, and the boards achieve a good interface under low-temperature, mild processing conditions, with the process conforming to green chemistry principles.

[0040] Implementation 6 Please see Figures 1-6 A green, continuous manufacturing process for chemically modified and reinforced composite materials, suitable for large-format, high-speed production lines: continuous production of large composite panels for building partitions, including online data-driven adaptive control. Target product: Large-format composite building partition, example size 1.2m × any length, thickness 3-10mm, matrix PLA and recycled PP mixed, reinforced with short-cut mixed natural fiber + glass fiber mixed phase, nanocellulose 1wt%.

[0041] Equipment and production line configuration: high-throughput parallel interlocking twin-screw extruder (capacity 500-2000 kg / h), multiple plasma treatment modules in parallel, wide-width vacuum impregnation tank (width ≥ 1.5m, zoned vacuum control), multi-point ultrasonic distributor, infrared + microwave continuous curing section (zoned temperature control), full-line heat recovery and water recovery system, online sensor array (NIR, ultrasonic, thickness, imaging) and process control unit based on lightweight machine learning (edge ​​computing).

[0042] Process parameters: Parallel plasma processing: Multiple pairs of electrodes are used for partitioning, with a processing line speed of 0.8-2.0 m / min, which can process multiple bundles of fibers or wide fiber mats in parallel. Dry grafting and extrusion: The matrix mixture undergoes in-situ grafting reaction at 180-220℃ in a twin-screw extruder, with the screw speed adjusted according to the production capacity (200-500 rpm). Wide-range vacuum impregnation: multi-zone independent vacuum adjustment (5-50kPa), impregnation belt speed 0.2-2.0m / min, ultrasonic array covering the entire range, ultrasonic frequency zoned 20-40kHz; Combined short-time curing: infrared and microwave zoned synergy, microwave power is allocated according to bandwidth, total power is 5-50kW, curing time is 30s-10min (depending on thickness). Online control: Data from NIR 700-2500nm (5-20Hz), ultrasonic detection (0.5-5MHz), and high-speed camera (500-2000fps) are input into the edge computer. The trained lightweight regression and classification model outputs adjustment commands for temperature, vacuum, linear speed, and ultrasonic power, which are then sent to the PLC.

[0043] Achieving wide-width parallel plasma activation and multi-point ultrasonic dispersion enables large-area composite plates with controllable width and thickness to achieve uniform interface modification and defect-free impregnation at continuous high production rates.

[0044] Integrating online multimodal sensing and edge machine learning for closed-loop adaptive control, the system dynamically adjusts process parameters to compensate for raw material fluctuations (recycled materials, fiber moisture content, etc.) and ensures batch-to-batch consistency of products.

[0045] The production line is suitable for industrial mass production, with a reduced defect rate. Energy consumption is significantly reduced through zoned heat recovery and short-time curing. Data-driven control allows for rapid and stable switching between different raw material batches.

[0046] Performance test: The following provides detailed experimental designs, sample preparation procedures, testing methods, and representative data for the previous six embodiments; all experiments are written with reproducible procedures at the laboratory / pilot scale; the numerical values ​​are exemplary and repeatable experimental results.

[0047] General testing equipment and sample preparation instructions: General equipment: Universal testing machine with adjustable loading rate; Impact testing machine, differential scanning calorimeter, thermogravimetric analyzer, infrared spectrometer, scanning electron microscope, transmission electron microscope, XRD, surface resistivity meter, and near-infrared spectrometer are used for in-line comparison.

[0048] Sample pretreatment: All samples were placed under standard conditions (23±2℃, relative humidity 50±5%) for at least 48 hours before sampling and testing; samples designed for moisture absorption and aging were accelerated under conditions such as 70℃ / 85%RH and 1000h to evaluate durability.

[0049] Sample size: Tensile test: 150×10×2mm canine bone-shaped strip or long strip, tensile rate 5mm / min; Bending: Three-point bending spline 80×10×2mm, span is 16 times the length of the spline, loading rate is 2mm / min; Peeling, short beam shear (interface strength): The template is designed according to short beam shear or single fiber pull-out; Water absorption test: The sample was cut into 20×20×2mm pieces, placed in distilled water at 23℃, weighed and recorded over time.

[0050] Microscopic and chemical characterization: SEM: Gold sputtering of fracture surface metal, voltage 5-15kV, to observe fiber interface and void distribution; FTIR: Compare the changes in functional groups (grafting / bonding characteristic peaks) of fibers and melt resin before and after treatment. DSC: Heating rate 10°C / min, measuring changes in Tg, crystallization temperature and crystallinity; TGA: Nitrogen atmosphere, heating rate 10°C / min, to determine thermal weight loss and 5% weight loss temperature.

[0051] Experiment 1: Verification: The improvement of interfacial bonding, mechanical properties and hydrothermal stability of composite sheets by the process of enzymatic aqueous pretreatment + plasma activation + aqueous silane sizing + extrusion in-situ grafting and ultrasonic vacuum impregnation.

[0052] Control group A: Pure PLA sheet (die-cast); Control group B: PLA + untreated short-cut hemp fibers; Experimental group C (this process): prepared according to the entire processing procedure of Example 1.

[0053] Test methods and conditions: Tensile test: Specimen size 150×10×2mm, tensile speed 5mm / min; Three-point bending: span 48mm, loading rate 2mm / min; Water absorption: soaked in room temperature water for 168h, weighed and recorded at intervals; Aging test: tensile strength was retested after 500h at 85°C / 85%RH; SEM observation: fracture surface and interface.

[0054] Example results are shown in Table 1 below: Table 1 Test Results of Experiment 1 sample Slight tension MPa Tensile modulus (GPa) Flexural strength MPa Water absorption rate % Strength retention rate after aging % A 58 3.2 95 0.6 92 B 50 3.8 105 1.8 76 C 68 4.6 132 0.9 89 SEM (fracture surface): Group B showed fiber pull-out voids and less resin filamentation, while Group C had a tight fiber-matrix interface and less pull-out, indicating that chemical grafting / size effectively improved interfacial adhesion.

[0055] FTIR: Characteristic peaks (rising relative to baseline) related to maleic anhydride or silane appear on the melt and fiber surface in group C, supporting in-situ grafting and chemical bonding.

[0056] DSC: Group C shows a slightly increased crystallinity (compared to A and B), indicating that nanocellulose and fibers contribute to the nucleation effect.

[0057] Conclusion: The process in the example improved the composite properties through interfacial chemical modification and nano-dispersion, especially significantly improving flexural strength and modulus, and also markedly improving hygrothermal stability.

[0058] Experiment 2: Verification: The effect of in-situ MAH grafting on recycled PP, plasma-sized glass fiber and electrostatic and vacuum impregnation on improving the mechanical and dimensional stability of recycled matrix composites.

[0059] Compare to D:rPP sheet; Control E: rPP + 20wt% untreated glass fiber + 2wt% MMT; Experiment F (Example 2 of this process): rPP was grafted in situ with MAH (2wt% MAH equivalent), glass fiber was subjected to plasma and aqueous silane sizing (4wt%), MMT was added as masterbatch and electrostatically assisted impregnation, and vacuum degassing was performed.

[0060] Test methods: tensile, bending, short beam shear test, thermal expansion dimensional stability (thickness and length changes after 10 thermal cycles at 20-80℃); flame retardant or thermogravimetric analysis (TGA) to evaluate the nano-clay effect.

[0061] Example results are shown in Table 2 below: Table 2 Test Results of Experiment 2 sample Stretching slightly MPa Flexural strength GPa short beam shear strength (MPa) thermal expansion change % D 28 45 - 0.85 E 62 110 8.5 0.9 F 82 150 12.3 0.45 SEM: Group F showed good wetting of glass fiber and matrix with no obvious cracks at the interface; Group E showed micro-debonding of fiber and micro-voids.

[0062] TGA: The 5% weight loss temperature of group F is slightly higher than that of group E, and the char residue is increased (MMT dispersion is improved).

[0063] Conclusion: In-situ grafting significantly improves the compatibility of recycled PP and glass fiber, while electrostatic and vacuum impregnation improves the interlayer delamination / dispersion of nano-clay, resulting in improved mechanical and dimensional stability.

[0064] Experiment 3: Verify the effects of peroxide-induced in-situ grafting of monomers in the melt and PUD size on the improvement of basalt fiber-PE interfacial wettability and profile properties.

[0065] Reference G: HDPE profiles (excluding reinforcement); Reference H: HDPE + 15wt% basalt fiber (untreated); Experimental Group I (Example 3 of this process): HDPE + 15wt% basalt fiber (after PUD size) + in-situ initiation grafting (1wt% monomer, 0.5wt% peroxide initiator). Tensile and bending tests, interfacial single fiber pull-out force test, and retest after 200h of heat aging (80°C).

[0066] Example results are shown in Table 3 below: Table 3 Test Results of Experiment 3 sample Tensile strength (MPa) Tensile modulus (GPa) Single fiber pull-out force N G 32 0.9 - H 58 2.0 0.45 I 76 2.8 0.95 The interfacial pull-out force is significantly improved (approximately 2.1 times that of Group H in Group I), supporting grafting / size-enhancing bonding strength.

[0067] DSC / TGA showed that grafting did not cause significant degradation, but the crystallization rate changed moderately.

[0068] Conclusion: In-situ grafting combined with waterborne PUD dimensions significantly improves interfacial adhesion in the extrusion profile process and is suitable for continuous production of structural profiles.

[0069] Experiment 4: The study verified that ultrasonic melt segment combined with electrostatic directional impregnation enables the formation of a connected network of low-content conductive phases and significantly reduces surface resistance while maintaining mechanical properties.

[0070] Reference J: PLA + 10wt% glass fiber (no conductive phase); Reference K: Same as J + 1.0wt% conductive phase (CNT+GO) but without electrostatic orientation; Experimental group L (Example 4 of this process): Same as J + 1.0wt% conductive phase, using ultrasonic melt dispersion + impregnation electrostatic orientation.

[0071] Sheet resistance (Ω / area) measurement (four-probe method), tensile / bending mechanical testing, conductive phase microstructure distribution SEM / TEM.

[0072] Example results are shown in Table 4 below: Table 4 Test Results of Experiment 4 sample Surface resistance Ω / surface Tensile strength (MPa) illustrate J <![CDATA[>1×10 9 ]]> 65 insulation K <![CDATA[5×10 7 ]]> 62 The conductive phase is not well dispersed, resulting in high resistance. L <![CDATA[1.2×10 6 ]]> 64 Electrostatic orientation combined with ultrasound achieves lower resistance while maintaining good mechanical properties. SEM / TEM: Group L shows that the conductive phase is partially connected along the fiber / flow direction, while the conductive phase in Group K still has blocky agglomerations.

[0073] Conclusion: Electrostatic orientation combined with ultrasonic dispersion can achieve a usable conductive network with low filler content in continuous production while maintaining the mechanical integrity of the material.

[0074] Experiment 5: To verify the effect of DES impregnation as a green grafting / surface activation medium on reducing interfacial grafting efficiency and environmental impact under recycling and reuse conditions.

[0075] DES: Choline chloride: Glycerol 1:2 (containing 1 wt% grafted monomer).

[0076] The fibers were continuously contacted at 50°C for 30-60 seconds, and then DES ≥ 90% was recovered.

[0077] Control group M: PHBV + jute (untreated).

[0078] Experimental group N (Example 5 of this process): PHBV + jute (DES treatment + plasma + PHBV extrusion in situ grafting).

[0079] Example results are shown in Table 5 below: Table 5. Test Results of Experiment 5 project M (Unprocessed) N (This process) Tensile strength (MPa) 28 38 Contains residual DES% 0.0 (Unused) <0.2 (after recycling) Grafting Evidence FTIR none Grafting characteristic peaks appear Environmental emissions VOCs and other measurements - VOC emissions are significantly low. DES is effective as a low-volatility, recyclable grafting medium; recovery rate and residual tests show that recycling is feasible.

[0080] Conclusion: The examples demonstrate quantifiable environmental advantages in “green grafting” while still improving the mechanical properties of the composite material.

[0081] Experiment 6: Evaluate the impact of wide-range parallel plasma, multi-point ultrasound, online multimodal sensing, and edge ML control on production capacity, defect rate, and energy consumption.

[0082] Production capacity: Linear speed 1.0m / min, bandwidth 1.2m, continuous working capacity ~720kg / shift (8h).

[0083] Defect rate (based on online detection rejection / rework): approximately 6.8% for traditional lines (without online adaptive testing), and approximately 1.4% for this implementation line.

[0084] Energy consumption (including heating, vacuum, and ultrasound): Traditional batch production of the same output is about 25 kWh / kg, while this process (short-time curing + heat recovery) is about 12 kWh / kg.

[0085] Heat recovery efficiency (waste heat recovery for preheating / drying): approximately 45-60%.

[0086] Product batch consistency (thickness standard deviation): traditional line ±8-10%, this line ±2-3%.

[0087] When the moisture content of the raw material fluctuates from 0.5% to 3.5%, the edge ML model automatically adjusts the ultrasonic power and vacuum degree, and the output thickness and void ratio are kept within the target range (thickness deviation < ±3%), while the deviation of the control group is > ±10% when there is no control.

[0088] Quality example test (randomly selected finished sheets, n=20): average tensile strength 70MPa, standard deviation 2.5MPa; average void ratio 0.6%.

[0089] Working principle: This process utilizes a modular continuous production line, sequentially comprising: raw material pretreatment → surface activation → functionalization and grafting → in-situ melt reaction extrusion → vacuum impregnation → roll pressing and degassing → short-time mixing and curing → cooling, winding, and cutting. Each module continuously transfers materials via belt conveyor, roller conveyor, or extrusion linkage, maintaining sealing or zoned vacuum and temperature control between modules to achieve simultaneous physical and chemical modification. This integrates the chemical modification of fiber and water-containing paste-like alkaline slag surfaces with in-situ chemical grafting of the matrix, high uniform dispersion of nanophases, and degassing and shaping into a unified continuous process.

[0090] At the chemical level, a combination of aqueous enzymatic selective exposure and atmospheric pressure plasma corona treatment first generates active sites such as hydroxyl and carboxyl groups on the surface of fibers and aqueous paste-like alkaline slag. Subsequently, aqueous or low-VOC grafting agents are used to chemically graft the surface or form functionalized layers. In parallel, in-situ grafting of the matrix is ​​performed in parallel or series-connected twin-screw reactive extrusion sections, allowing the matrix and functionalized fibers to establish a stable interface through covalent or chemical bonding. The nano-reinforcing phase is unentangled and dispersed in the high-shear zone and ultrasonic module, while the vacuum impregnation process ensures that the melt resin fully wets the fibers and removes pores in the degassing zone. Short-time mixing and curing completes crosslinking or curing in the shortest possible time, reducing thermal degradation and internal stress.

[0091] The production line deploys multimodal online sensors at key nodes to collect real-time information on material distribution, moisture content, resin percentage, void ratio, and dimensions. The data is then processed by edge computing or PLC-embedded models to extract features and drive closed-loop control. Simultaneously, solvent, DES recovery, heat recovery, and exhaust gas treatment are integrated to form a closed-loop resource utilization system, ensuring consistency, repeatability, and environmental compliance in continuous production.

[0092] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A green and continuous preparation process for chemically modified and reinforced composite materials, characterized in that: The preparation process is performed sequentially and includes the following steps: A. Mechanically classify and dry the reinforcing fibers or water-containing paste-like alkali residue; B. The fiber or water-containing paste-like alkaline residue obtained in step A is subjected to aqueous enzymatic pretreatment in a continuous flow contactor; C. The fiber or aqueous paste-like alkaline residue obtained in step B is activated online by atmospheric pressure plasma or corona discharge; D. The fiber or water-containing paste-like alkaline residue obtained in step C is subjected to continuous coating size treatment. The coating method is one of spraying, dipping or scraping. The subsequent drying is ventilated belt drying. E. The thermoplastic matrix material, grafted monomers or grafting aids and nano-reinforcing agents are continuously added into a twin-screw reactive extruder and reactive extrusion is carried out; F. The functionalized fibers processed in step D are fed into the vacuum impregnation tank by directional laying or continuous winding, while ultrasonic or high-frequency vibration is applied in the impregnation section. G. The impregnated strip is degassed and shaped by continuous calendering or vacuum roll pressing. H. A hybrid infrared and microwave heating device is used to cure the strip for a short time in the later stage of calendering; I. Set up an online detection unit on the production line. The detection unit is connected to a programmable controller to record and output detection signals; J. Cool, cut or wind the strip obtained after step H.

2. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The mechanical grading is performed with a sieve aperture of 0.05-5.0 mm. Drying is carried out using a continuous belt dryer or a fluidized bed dryer at a temperature of 60-120℃, with a residual moisture content of ≤2.0 wt%.

3. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The enzyme used in the enzymatic pretreatment is selected from cellulase, pectinase, xylanase or a mixture of two or more, and the amount of enzyme used is 0.01-1.0 wt% based on solid mass. The reaction temperature is 30-60℃, the pH value is 4.5-8.0, and the residence time in the continuous reactor is 10-240 s. The continuous flow contactor is a series static mixer or a disc reactor. The liquid-to-solid volume ratio of the enzyme solution to the fiber is 5:1-50:1, and it is equipped with an online pH adjustment device to maintain the pH within the set range.

4. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The plasma processing gas is air, oxygen, nitrogen, or a mixture of the above, and the processing power density is 0.01-10 W / cm³. 2 The processing linear velocity is 0.1-10 m / min; The plasma device includes a gas gap discharge unit formed by at least one pair of parallel electrodes, a gas flow rate of 0.1-10 L / min·cm amplitude, a processing voltage of 1-20 kV, and a processing frequency of 10-100 kHz.

5. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The coating size treatment uses one of the following: an aqueous silane emulsion, a polymeric multifunctional grafting agent, or a bio-based polymer emulsion. The coating solid content is 1.0-8.0 wt%, the drying temperature is 50-120℃, and the residual solvent is ≤0.5 wt%. The aqueous silane emulsion consists of 5-50 wt% silane coupling agent, 1-20 wt% film-forming aid, water, and dispersant, with a viscosity of 50-500 mPa·s. After spraying or impregnation, the solid content is brought to the target value through an infrared pre-drying section.

6. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The matrix material is selected from PLA, PP, PE, or recycled materials of the above materials. The temperature gradient in the extrusion section is 120-250℃, the screw speed is 100-600rpm, the grafting agent dosage is 0.2-5.0wt% of the matrix mass, and the nano-reinforcing agent dosage is 0.1-8.0wt% of the matrix mass. The twin-screw reactive extruder uses a parallel interlocking twin-screw design. The barrel is divided into at least six temperature zones: the first zone is 120-160℃, the middle zone is 150-220℃, and the tail zone is 160-250℃. The feed ratio is matrix:grafting agent:nano-reinforcing agent = 100:(0.2-5.0):(0.1-8.0). The extruder is equipped with a side inlet for adding nano-reinforcing agents and a high-shear dispersion section.

7. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The vacuum impregnation tank has a vacuum level of 5-50 kPa, a relative impregnation speed of 0.05-2.0 m / min, an ultrasonic frequency of 20-40 kHz, and an ultrasonic power density of 0.1-5.0 W / cm³. 2 ; The vacuum impregnation tank has a multi-stage vacuum partition structure, including an inlet preheating zone, an impregnation main tank, and a degassing zone. An ultrasonic transmitter and electrode pair are installed in the impregnation main tank. The maximum voltage of the electrode pair is 50kV, and the electrode frequency is 1-100kHz.

8. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The vacuum rolling section includes an upper roller and a lower roller. The surface temperature of the upper roller is controlled at 80-220℃, the surface temperature of the lower roller is controlled at 60-200℃, the roller gap is adjustable from 0.01-5.0mm, and a vacuum degassing chamber is set after rolling. The vacuum degree of the degassing chamber is 1-50kPa. The working pressure of the calendering roll is 0.1-5.0 MPa, and the linear speed is 0.05-3.0 m / min.

9. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The detection unit includes a near-infrared spectrometer (NIR), an ultrasonic detection probe, a thickness sensor, and a high-speed imaging camera. The near-infrared spectrometer (NIR) measures wavelengths from 700 to 2500 nm and has a sampling frequency of 1 to 50 Hz; the ultrasonic testing probe has a center frequency of 0.5 to 10 MHz and a sampling frequency of 1 to 10 kHz; the thickness sensor has a resolution of ≤10 μm; the high-speed imaging camera has a frame rate of 100 to 5000 fps; and the programmable controller is a PLC or industrial computer with at least 8 analog inputs and 16 digital input / output interfaces.

10. The green and continuous preparation process of chemically modified and reinforced composite materials according to claim 1, characterized in that: The microwave and infrared hybrid heating device consists of an infrared radiation unit and an industrial microwave cavity arranged side-by-side within the same curing section. The microwave cavity frequency is either 915MHz or 2.45GHz, the continuous power of the microwave cavity is 0.1-50kW, and the radiation power density of the infrared unit is 0.1-5.0kW / m². 2 The curing section is equipped with no fewer than three temperature sensors for temperature acquisition and output to the control bus; The cooling temperature is 5-60℃, and the winding tension is 0.1-5.0 N / cm.

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