Improving Tensile Properties of Glass Fiber-Reinforced Epoxy Resin Composites Based on Enhanced Multiphase Structure: The Modification of Resin Systems and Glass Fibers

An optimized processing method for glass fiber-reinforced polymers (GFRP) composites was developed, significantly enhancing the tensile properties of GFRP laminates. This study investigates the impact of functional curing agents, silane coupling agents (SCA)-treated glass fibers (GFs), and nanomaterials on GFRP's tensile properties. The findings revealed a 7.15% increase in the ultimate tensile strength (UTS) of GF bundles due to film formation by SCA. Epoxy resin, modified with functionalized nanomaterials, exhibits an increase in breaking elongation (7.76%) and fracture toughness (1.52 MPa). In contrast, resin enhanced with functional curing agents demonstrates a higher UTS, attributable to its rigid chemical structure. Variations in ply thickness distinctly influence the tensile properties and failure modes of GFRP laminates. Laminates comprising four-ply prepregs facilitate more effective load transfer across the matrix-fiber boundary, yielding optimal tensile properties for GFRP. The ultimate strain is improved for laminates utilizing diverse resin systems by increasing the resin matrix's ductility and UTS. In addition, the enhancement of interfacial adhesion between GFs and the resin matrix through SCA further boosts the tensile properties of the laminates. The enhancement mechanism of the multiphase structure in GFRP is elucidated using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and the contact angle measurements between resin and GFs. These analyses indicated that the multiphase structures in GFRP, enhanced by SCA, nanomaterials, and functional curing agents, significantly improve its tensile properties.