Inorganic particle toughening I: micro-mechanical deformations in the fracture of glass bead filled epoxies

General characteristics of micro-mechanical deformations found in the fract ure of various glass bead filled epoxies are investigated. Among the variou s types of step features on fracture surfaces, the basic longitudinal textu re is not influenced by the existence of glass beads, but most other steps formed are significantly affected. Various microscopic investigations show that microcracking does not extensively occur in the fracture of glass bead filled epoxies. Microcracking other than debonding of glass beads is seldo m observed, and furthermore, debonding is found to occur only on and near t he fracture surface. Micro-shear bands are clearly identified and distingui shed from microcracks found in unnotched tensile specimens. Based on examin ation of micro-mechanical deformations, three types of fracture processes a re proposed for glass bead filled epoxies having different glass bead conte nts and interfacial strengths. (C) 2000 Elsevier Science Ltd. All rights re served.