Hongxiao Wang

A polymethyl methacrylate/methyl methacrylate (PMMA/MMA) binary liquid resin (PMBLR) was employed to fabricate polyimide‐, aramid‐, and ultrahigh‐molecular‐weight polyethylene (UHMWPE)‐fabric‐reinforced PMMA composites via vacuum‐assisted resin infusion (VARI). The low porosity of polyimide/PMMA (0.171%), aramid/PMMA (0.251%), and UHMWPE/PMMA (0.058%) demonstrated effective impregnation of the three fabrics by the PMMA/MMA resin. Mechanical testing showed that the tensile strengths of polyimide/PMMA, aramid/PMMA, and UHMWPE/PMMA decreased from 728 to 623 MPa, from 667 to 554 MPa, and from 485 to 409 MPa, respectively, as the temperature increased from −30°C to +50°C, corresponding to reductions of 14%, 17%, and 16%. The three composites showed comparable short‐beam strengths (14.37–14.76 MPa), but Polyimide/PMMA exhibited a stiffness‐dominated, high‐load‐bearing response, with the highest flexural strength (206 MPa) and impact strength (233 kJ/m ² ). Its flexural and impact strengths were 17% and 28% higher than those of Aramid/PMMA, and 137% and 36% higher than those of UHMWPE/PMMA, respectively. Aramid/PMMA exhibited intermediate mechanical performance, whereas UHMWPE/PMMA showed a more compliant response with lower flexural and impact strengths. MMA‐assisted dissolution removed the PMMA matrix while preserving the macroscopic integrity of the organic fabrics, supporting the feasibility of fabric recovery from these PMMA‐based composites.

Continuous carbon fiber reinforced polycarbonate (CCF/PC) prepreg filaments hold broad prospects in additive manufacturing; however, they still face challenges such as limited thermal properties, low matrix strength, and weak interlaminar interfacial adhesion after 3D printing. This study proposes a synergistic reinforcement strategy, specifically, by introducing carboxylated multi‐walled carbon nanotubes (MWCNT‐COOH) into a polycarbonate (PC) suspension, polycarbonate/carbon nanotube (PC/CNT) suspensions are prepared, and high‐performance CCF/PC‐CNT prepreg filaments suitable for fused deposition modeling (FDM) are prepared using solution impregnation‐thermal traction technology. That not only improves the heat resistance but also enhances the matrix strength and the 3D‐printed interfacial properties. The results indicate that when the CNT content is 1.5 wt%, the glass transition temperature (T _g ) of the PC/CNT increases by approximately 5°C, and the heat resistance and wettability of the PC resin are improved. Furthermore, the tensile strength of the prepreg reaches 1655 MPa, representing a 16% increase compared to the neat PC group. After 3D printing, the interlaminar shear strength (ILSS) of the specimens increases by 34% compared to the control, reaching 45 MPa. Correspondingly, the fracture mechanism transforms from typical interfacial debonding to cohesive matrix failure with higher energy dissipation, indicating that the interfacial properties are improved.

To reveal the effects of internal defects introduced by the automated fiber placement (AFP) process on the flexural performance and damage evolution behavior of CFRP laminates, orthogonally laminated CFRP plates, and CFRP laminates containing artificially introduced gaps were fabricated using AFP. Real internal structural data at different damage stages were obtained by combining three‐point bending tests with X‐ray micro‐computed tomography. Based on these data, a three‐dimensional model incorporating the true internal morphology was established, and defect evolution during damage was quantitatively characterized, while finite element simulations were conducted to investigate stress concentrations around pores and gaps under flexural loading. The results showed that the gap‐containing specimens showed an average maximum load of 834.62 N and an average flexural strength of 243.15 MPa, representing reductions of 30.17% and 31.34%, respectively, compared with the normal lay‐up. The normal lay‐up exhibited a progressive damage sequence from early intralaminar pore expansion to interlaminar damage and late‐stage crack‐dominated failure. In contrast, the gap‐containing specimens had consistently higher defect volume fractions and an earlier crack peak, indicating that the introduced gaps accelerated damage initiation, propagation, and localization.

In this study, a recyclable polymethyl methacrylate (PMMA)‐based sandwich composite was fabricated by vacuum‐assisted resin infusion, with upper and lower layers of single‐layer carbon fiber fabric (CFF) (0°/90°) and a hollow glass microsphere (HGM)‐filled PMMA foam core. The effects of HGM content on density, mechanical performance, electromagnetic shielding performance, and recyclability were systematically examined. Incorporating HGM reduced the density from 1.14 to 0.8 g/cm ³ and improved bending (357.33 MPa), impact (49.08 kJ/m ² ), and tensile strengths (134.54 MPa) by 3.6%, 36.9%, and 4.6%, respectively, while the bending (22.69GPa) and tensile (14.67GPa) moduli increased by 34.5% and 14.2%, respectively. Micromechanical simulation revealed that improved interfacial bonding mitigates stress concentrations and promotes effective load transfer, consistent with the experimental results. The composite also showed a 30.5% increase in electromagnetic shielding effectiveness (SE) (61.45 dB) and an 86% increase in specific shielding effectiveness (SSE) (76.81 dB/(g/cm ³ )), driven by the synergistic reflection–absorption effects of the CFF and HGM. Furthermore, a methyl methacrylate (MMA)‐based separation enabled efficient recovery of CFF, PMMA, and HGM, and the regenerated sandwich panel retained over 96% of its original strength and modulus.

Conventional manufacturing processes for thermoplastic composites typically rely on external heating sources, resulting in high energy consumption and extended processing cycles. To overcome these limitations, this study applied self‐resistance electric (SRE) heating technology to fabricate carbon fiber‐reinforced polymethyl methacrylate (CF/PMMA) composites via compression molding. Initially, the electrical conductivity of the prepreg was measured to establish a temperature‐current correlation model based on experimental data, validating the feasibility of the SRE heating process. The physical properties, interfacial characteristics, porosity, and mechanical performance of the resulting composites were systematically characterized. The results demonstrate that SRE heating significantly shortens the consolidation cycle, reducing the total processing time to approximately 22% of that required for conventional hot pressing. Although SRE processing leads to a higher porosity (3.72%) and a corresponding reduction in tensile strength (−9.2%), the flexural strength is enhanced by 11.8%, attributed to improved interfacial load transfer in surface plies. These findings indicate that internal Joule heating provides an efficient manufacturing route for PMMA‐based CFRTPs where reduced cycle time and flexural performance are critical.

Continuous carbon‐fiber reinforced polycarbonate ( CCF / PC ) prepreg filaments are promising feedstocks for 3D printing, yet their fabrication remains challenging due to the high melt viscosity of PC , which hampers resin infiltration and commonly requires high processing tension, resulting in void defects and fiber damage. In this work, a synergistic suspension pre‐impregnation and melt‐impregnation process is proposed to uniformly deposit PC powders onto carbon fiber prior to melt consolidation, thereby improving infiltration efficiency without the need for damage caused by mechanical broadening and high tension traction. The effects of melt‐impregnation temperature (270°C–300°C) and drawing speed (7–21 mm/s) on microstructure, porosity, and tensile properties were systematically investigated. Under the optimized condition (290°C, 7 mm/s), the prepreg filament achieved a low porosity of 8 × 10 ⁻³ and a tensile strength of approximately 1550 MPa , which is only 3% lower than the theoretical value, indicating effective mitigation of fiber damage. 3D printing using the optimized filament produced unidirectional specimens with a tensile strength of about 875 MPa and a modulus of 78 GPa , demonstrating the feasibility of the proposed route for high‐performance continuous‐fiber thermoplastic additive manufacturing.

Establishes a unified thermo-mechanical coupling mechanism and process-window strategy for damage-controlled precision drilling of carbon fiber reinforced polymer composites.

Integrated melt-impregnation platform enables uniform, high-strength continuous carbon fiber/polyether ether ketone filaments (1559 MPa) with low porosity for reliable fused deposition modeling additive manufacturing.

Carbon fiber reinforced polyetheretherketone (CF/PEEK) composites possess excellent mechanical properties and thermal stability. However, during the processing of PEEK with large‐tow carbon fibers, there are challenges such as dense fiber arrangement and high viscosity penetration of the resin, which usually require complex fiber spreading or surface treatment. In this work, a novel aqueous suspension‐based impregnation process is developed to rapidly and continuously impregnate epoxy‐sized large‐tow carbon fibers with PEEK without any prior desizing or tow spreading. The suspension utilizes a multicomponent gradient‐evaporation solvent system (deionized water with ethanol, ethylene glycol, and NMP) combined with synergistic surfactants (PVP K30, PEG‐400, and Tween 80) to dramatically improve resin powder dispersion stability and lower interfacial tension. The addition of nano‐SiO ₂ and a silane coupling agent (KH560) further enhances fiber–matrix interfacial bonding. Zeta potential analysis confirmed that the optimized suspension (pH 9, 1.5 wt% surfactants) achieved high stability with no observable sedimentation for 1 h, and contact angle tests showed effective wetting on sized fibers (only 2° difference from desized). Using a custom continuous impregnation line, 48K tows were uniformly coated and consolidated at 1 m/min line speed. The resulting prepregs exhibited uniform resin distribution with fiber volume fractions of approximately 35% and porosity below 1%. A three‐hour continuous production run demonstrated consistent prepreg quality over time. These results highlight that the proposed multicomponent suspension and process enable fast, continuous manufacturing of high‐quality CF/PEEK prepregs from large‐tow fibers without additional fiber treatment, representing a significant advancement in scalable thermoplastic composite fabrication.

Variable‐curvature Carbon Fiber Reinforced Polymer (CFRP) stringers are prone to wrinkling defects during forming, and conventional techniques often fail to meet quality requirements. To reduce wrinkling defects during the forming of variable‐curvature CFRP stringers, this study proposes a novel forming method that begins with applying a triangular mesh flattening algorithm for initial flattening, followed by optimization using a mass‐spring (MS) model; based on the optimized results, forming blanks are fabricated via an automated fiber placement (AFP) process; finally, variable‐curvature CFRP stringers are produced on a self‐developed automated roll forming platform. The flattening results and forming experimental results indicate that, compared with the initial flattening method, the MS model–optimized approach achieves higher near‐net shape prediction accuracy, with the effective surface coverage of the stringers increasing from 86% to 98%, the wrinkled area decreasing to 1.21 × 10 ² mm ² from 5.06 × 10 ² mm ² , and the standard deviations of thickness and internal porosity reducing to 1.5 × 10 ⁻² mm and 0.41%, respectively, demonstrating that this method significantly reduces wrinkling defects during the forming of variable‐curvature CFRP stringers and provides a feasible pathway and theoretical support for their high‐quality forming.