Construction of interfacial interlocking structure in epoxy composites with enhanced mechanical performance and ultraviolet resistance

Replacing carbon fibers with organic fibers to reinforce the polymer matrix has become a promising development direction in the preparation of structural composites owing to its low density and cost, but the mechanical performance of organic fibers restricts their further application. Herein, poly(vinyl alcohol) (PVA) fibers were utilized to reinforce the epoxy resin (EP) through the incorporation of zinc oxide nanoparticles (ZnO NPs) in PVA solution (PVAS), and high-strength composite for 122.3 MPa with interfacial interlocking structure was successfully fabricated via vacuum resin transfer molding (VARTM). ZnO NPs were coated on the PVA fibers and enhanced the surface roughness, which improved the mechanical performance of the composite. In comparison with untreated composites, the interlaminar shear strength (ILSS) of composites displayed a significant increase, from 99.4 MPa to 122.3 MPa, resulting from improved interfacial bonding and reduced interfacial gap. Simultaneously, the incorporation of ZnO NPs efficiently enhanced the ultraviolet (UV) resistance.