COEXISTENCE OF DUCTILE, SEMIDUCTILE, AND BRITTLE FRACTURES OF ELASTOMER-MODIFIED POLYCARBONATES

Abstract

Phenomenologically, coexistence of ductile, semiductile, and brittle fractures in an apparently identical impact testing condition for the elastomer-modified polycarbonates containing a sharper notch and at high test temperatures has been found. At the ductile-brittle transition temperature, approximately 10% of specimens fractured in the semiductile mode with impact strength about the average of the ductile and brittle modes. The fracture surface of this semiductile mode shows ductile tearing flow in the plane-stress regions near the edges and brittle crack in the plane-strain central region. This unusual semiductile fracture occurs only on the thicker specimens with a sharper notch where clear plane-stress and plane-strain are present. (C) 1995 John Wiley and Sons, Inc.