Fracture toughness of epoxy polymer modified with nanosilica particles: Particle size effect

An epoxy resin was modified by the addition of different nanosilica particles. The particles were distributed into epoxy resin with ultrasonic instrument which gave a very well-dispersed phase of nanosilica particles. Tensile test and dynamic mechanical thermal analysis (DMTA) showed that Young’s modulus increased and the glass transition temperature was unchanged. The fracture energy increased to about 620 J/m2 for the epoxy with 3.17 vol.% of 12-nm diameter nanoparticles. The responsible toughening mechanisms were recognized to be plastic deformation and plastic void growth. Finally, the toughening mechanisms have been quantitatively modeled and an excellent agreement between the results was found.

► Three types of silica nanoparticles were used to toughen the epoxy resin.
► Tensile modulus and fracture energy increased as the volume fraction of silica.
► Plastic deformation and plastic void growth are the responsible toughening mechanisms.
► The toughening mechanisms have been quantitatively modeled.