MICROMECHANISMS OF FAILURE IN SHORT-FIBER-REINFORCED HIGH-IMPACT POLYSTYRENE UNDER TENSILE LOADING

Injection-molded, short-glass-fiber-reinforced high-impact polystyrene was investigated under uniaxial tension with special attention to the effects of fiber and rubber concentration on fracture behavior. According to a fracture morphology study performed by polarized optical and scanning electron microscopy, crazes were consecutively initiated from rubber-styrene composite particles and from fiber ends. The rubber particles exhibited an intra-particle failure mode which resulted from the failure manner of the matrix becoming of a more brittle character with increasing fiber fraction. Fibers were surrounded by neighboring growing crazes. Failure at the fiber-matrix interfaces proceeded with an increase in the number of crazes. With increasing concentration of the fibers, crazing at rubber particles appeared to be suppressed and crazing occurred more preferentially at the fiber ends, which accelerated a macroscopic fracture.