In this study, uniform-sized silica spheres were first synthesized by sol-gel reaction under a basic environment and their surfaces were modified to possess different functional groups including vinyl, epoxide and amino groups by reaction with 3-methacryloxypropyl trimethoxy silane (MPTMS), vinyl triethoxysilane (VTEOS), 3-glycidoxy propyltrimethoxy silane (GPTMS) and 3-Aminopropyl trimethoxysilane (APTMS). The functionalized silica spheres were characterized by FTIR, 29Si and 13C solid-NMR and SEM. These silica spheres with size ranging from 150~250 nm were then added to the pre-synthesized difunctional epoxyacrylate resin with one epoxide end group and one vinyl terminal groups. After photo- and thermal cure, mechanical properties and fracture toughness were measured to elaborate the effects of different functionalized silica spheres on the properties of epoxyacrylate-silica composites. Tensile mechanical properties including initial modulus, ultimate tensile strength and elongation at break, and also the fracture toughness of the epoxyacrylate-silica composite were all increased with increasing the amount of modified silica spheres. The increase of fracture toughness was due to the crack deflection and particle-matrix debonding as evidenced by SEM pictures on the fracture surface. Among these composites, the one filled with the MPTMS-modified silica had the best tensile mechanical properties and fracture toughness.
Proceedings of the Polymer Processing Society 29th Annual Meeting, pp.93