EFFECT OF PARTICLE-SIZE ON THE FRACTURE-TOUGHNESS OF EPOXY-RESIN FILLED WITH SPHERICAL SILICA

The effect of particle size on the fracture behaviour of cured epoxy resin filled with spherical silica particles was studied. Five kinds of spherical silica particles prepared by hydrolysis of silicon tetrachloride having different mean sizes, ranging from 6 to 42-mu-m, were used. The critical stress intensity factor (K(C)) and the critical strain energy release rate (G(c)) of the cured epoxy resins filled with the silica particles were measured. Both K(C) and G(C) values increased with particle size. Scanning electron microscope observation shows that the main crack propagation was hampered by large particles and a damage zone was formed at the main crack tip region in the large particle filled resin due to crack diversion and debonding of particle/matrix interfaces. The higher K(C) and G(C) values seem to be derived from these phenomena.