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

General characteristics of micro-mechanical deformations found in the fracture of various glass bead filled epoxies are investigated. Among the various types of step features on fracture surfaces, the basic longitudinal texture 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 seldom observed, and furthermore, debonding is found to occur only on and near the fracture surface. Micro-shear bands are clearly identified and distinguished from microcracks found in unnotched tensile specimens. Based on examination of micro-mechanical deformations, three types of fracture processes are proposed for glass bead filled epoxies having different glass bead contents and interfacial strengths.