Improved Interfacial Properties between Glass Fibers and Tetra-functional Epoxy Resins Modified with Silica Nanoparticles

The interfacial properties between fiber bundle and polymer matrix play a crucial role in determining the final performance of fiber-reinforced polymer composites. Epoxy modified with nanofillers as new "matrix" for the composites has been shown to be a possibility to enhance the interfacial properties between fiber bundle and "matrix". Herein, we synthesized silica nanoparticles with an average diameter of 80 nm through using the sol-gel technique and achieved a good dispersion of silica in tetra-functional epoxy matrix after intensively mechanical mixing procedure. The results revealed that incorporation of silica nanoparticles into epoxy increased its stiffness, strength and toughness simultaneously. Such silica/epoxy composite as new "matrix" showed a good impregnation in the fiber bundles, and thus produced improved interfacial properties between glass fiber bundle and new "matrix". For example, the presence of 15.0 wt% silica nanoparticles was found to produce 15 %, 22 % and 34 % in the elastic modulus, tensile strength and critical stress intensity factor of epoxy, respectively; and the interfacial strength between fiber bundle and the "matrix" was also enhanced by 58.3 %. Based on the fracture surface analysis, several possible mechanisms were proposed and discussed to understand the improved interfacial properties between glass fiber bundle and tetra-functional epoxy modified with silica nanoparticles.