Interfacial tailoring of continuous glass fiber reinforced PMMA thermoplastic composites via KH570 surface modification for enhanced mechanical and thermal performance

Continuous glass fiber (CGF)-reinforced thermoplastic composites fabricated by vacuum-assisted resin transfer molding (VARTM) often suffer from insufficient fiber–matrix interfacial bonding, which limits effective stress transfer and mechanical performance. In this study, γ-methacryloxypropyltrimethoxysilane (KH570) was employed to tailor the surface chemistry of CGF and enhance its interfacial compatibility with a polymethyl methacrylate (PMMA) matrix. After desizing and oxidative activation, CGFs were modified with varying KH570 concentrations (1–3 wt%) and subsequently incorporated into CGF/PMMA composites using a PMMA/methyl methacrylate binary liquid resin system. Surface morphological and spectroscopic analyses confirmed successful silane grafting, with a uniform and continuous interfacial layer achieved at 2 wt% KH570. The optimized interfacial structure significantly enhanced interfacial adhesion, leading to improved thermomechanical stability and mechanical properties. Compared with the composite reinforced with as-received CGF, the composite containing 2 wt% KH570 exhibited increases of 43.3% in 90° tensile strength, 19.3% in 0° tensile strength, 19.6% in flexural strength, and 28.5% in short-beam shear strength. These enhancements are attributed to improved interfacial stress transfer and restricted polymer chain mobility at the fiber–matrix interface.