Toughening of epoxy by inclusion of cellulose particles

Abstract

By inclusion of cellulose particles, the fracture toughness of modified epoxies was considerably enhanced without loss of its inherent properties, such as modulus and yield stress. The fracture toughness of modified epoxies is not affected by the crosslinking density of epoxy, but affected by aspect ratio of cellulose particles. The maximum fracture toughness can be obtained by using cellulose particles with aspect ratio 8. The increase in toughness in this system seems to arise from a combination of processes that include crack bifurcation, crack bridging, ductile fracture of cellulose, particle pull-out, and defibrillation. Among them, crack bridging and pull-out mechanisms are suggested as dominant toughening mechanisms for cellulose-modified epoxies.