Mechanical Properties and Fracture of Hybrid Particulate Composites

Abstract

A rigid epoxy resin was modified by acrylic core-shell particles and glass beads (with and without surface treatment). Glass transition temperature, elastic modulus and fracture toughness were determined for all formulations. The fracture toughness increased linearly with the rubber content (from 0.82 MPa√m for the neat resin to 2.6 MPa√m for 20% rubber). Toughness also increased on adding glass particles (for 50% glass up to 1.9 and 2.3 MPa√m depending on the surface treatment). The stress-strain behaviour in compression depended on glass content and surface sizing. The fracture behaviour markedly depended on the radius of curvature of the crack tip. The toughness of sharply cracked samples increased on increasing the glass content. On the contrary samples containing blunt cracks were embrittled by the hard particles. This was attributed to crack tip sharpening caused by detached beads.