Mechanical Properties and Fracture Behavior of Dual-Curable Epoxyacrylate Composites Filled with Different Functionalized Silica Particles

To investigate the interfacial effect on properties of epoxyacrylate-silica composites, sub-micron silica particles were synthesized by sol-gel reaction in an ammonia/ethanol solution and their surfaces were endowed with different functional groups by reaction with several silanes including 3-methacryloxypropyl trimethoxysilane (MPTMS), vinyl trimethoxysilane (VTMS), 3-glycidoxypropyl trimethoxysilane (GPTMS) and 3-aminopropyl trimethoxysilane (APTMS). Except the APTMS-modified silica particles due to its severe aggregation, the modified silica particles with size ranging from 150 similar to 250 nm were then added to the pre-synthesized difunctional epoxyacrylate resin at a concentration of 15 phr, in addition to the photo- and thermo-curing agents. Tensile mechanical properties and the fracture toughness were all increased by adding the silica particles into the epoxyacrylate. Particularly, the composite filled with the MPTMS-modified silica particles (EA-MPS 15) had the best performance. The reason is that the vinyl double bond of the MPTMS on the surface of the silica particles could took part in the curing reaction of the epoxyacrylate, thus providing strong interfacial chemical bonding between the silica particles and the polymer matrix and also improving the dispersion of the silica particles. The increase of fracture toughness was due to the crack deflection and particle-matrix debonding as evidenced by SEM pictures on the fracture surface.