In this study, ultrahigh-molecular-weight polyethylene (UHMWPE) fibres, modified by acetic acid, sulfuric acid and water at a ratio of 20:25:2 for different time periods and modified UHMWPE/EP composites were prepared. The micromorphology, chemical composition, contact angle, H sample extraction, tensile properties and bending performance of the composite material of the UHMWPE fibres before and after modification were tested and analysed. The results show that, after the UHMWPE fibres were treated with the modified liquid, the surface roughness of the fibre increased, the contact angle decreased, and the surface chemical composition and species significantly changed; the mechanical properties of the composites are best when the fibres were treated for 9 min. For the same fibre content, the specific strength, specific modulus and bending load of UHMWPE composites treated for 9 min were increased by 16.7%, 82.9% and 55.3%, respectively, compared with untreated samples.

The composite modification is a method of modifying the surface of ultra high molecular weight polyethylene (UHMWPE) fabric through the surface grafting, at the same time the epoxy resin through ultrasonic and 3- amino propyl triethoxy silane (KH550), and then using the vacuum assisted resin transfer molding (VARTM) process to prepare the composite. Explore the improvement of the interface between fiber and resin so as to optimize the mechanical properties of the material. The modification effect, the mechanism of action and the effect of different KH550 contents on the properties of the composite were studied. Compared with the unmodified sample, When 1wt% KH550, the maximum tensile load, tensile strength and the tensile fracture length increased by 13.83%, 20.19% and 51.27%, respectively, and the tensile modulus was reduced by 29.74%. The maximum bending stress and bending modulus of the 1wt% KH550 sample were increased by 104.57% and 190.97%, respectively. The displacement, which is related to the maximum loading, the pressure and the tension area of the resin decreased by 7.81%. The KH550 content had a substantial influence on the thermal decomposition temperature of UHMWPE, and it had a small effect on the epoxy resin. A KH550 content of 1wt% strengthened the bonds between the fibre and the resin, such that the main failure mode of the pressure area was the hickies, and the tension areas contained hickies and cracks.

This work presents a study of liquid oxidation modification effects on the tensile properties of UHMWPE fibers and UHMWPE fiber/epoxy composites. Three types of basic knitted structural composites were produced with 4, 6, and 8 layers. The shop-vacuum-assisted resin transfer molding (VARTM) process was used to laminate the composite. The tensile properties of the composite laminates were evaluated using a universal strength testing machine, and the tensile damage of the materials was analyzed. The results show that for the same number of layers of laminates, the tensile strength of the weft jersey structure was the highest, followed by those of the rib and cardigan structures. The tensile strength increased with the number of layers and increased with a nonlinear positive correlation. After modification, the stretching process did not result in yarn being pulled from the resin. The adhesion to the fabric and the resin increased, and the shear strength of the composite increased between the layers.

This study investigated the impact and post-impact behavior of different layer weft plain knitted composite materials based on modified ultra-high-molecular-weight polyethylene/epoxy composites. The modified ultra-high-molecularweight polyethylene weft plain knitted composites with 8, 12, 16 layers were prepared by vacuum-assisted resin transfer molding process and then subjected to impact and post-impact compression test. The impact properties were analyzed using the contact force-deflection and energy-time curves, and the post-impact compression was analyzed using the compression strength-strain curves. It can be obtained that the maximum contact force, absorbed energy, and residual compression strength after impact of the 16-layer specimen are 81.40%, 74.18%, and 73.25% more than those in the 8-layer specimen. respectively. According to the ultrasonic C-scan tests for the impact samples, the 16-layer specimen had the least damage area after the impact test, and the 8-layer composites damage area was 117.45% more than the 16-layer specimen.

UHMWPE fiber weft-knitted fabric was modified using a VARTM liquid oxidation molding process. The matrix was epoxy resin. The layer was prepared with vertical symmetry by knitting composite layers 10 and 16 with the unmodified and modified plain weft-knitted fabric of the composite using the two-layer blessing method. Three-point unconstrained bearings were used to conduct tensile and bending tests, and tensile stress-strain curves were obtained using Origin software. Finally, the modification results were observed using a TM3030 scanning electric microscope (SEM). The SEM results reveal longitudinal notches on the treated fiber surface, which improved the interface adhesion to the resin. However, the single yarn strength was reduced by approximately one fifth. After the modification, the knitted fabric's maximum tensile strength increased by 37.7%, and the maximum tensile strength increased by 46.35 percent. The maximum bending force increased by 37.3-53%, and the maximum bending load increased by 53.3-62 percent.