Mechanisms of failure of polymeric resins reinforced with high-modulus polyethylene fibres—A microscopy investigation

Previous publications (Ladizesky et al., Clinical Materials, 6 (1990) 209; Ladizesky et al., Australian Dental Journal, (in press) reported on three-point bending tests of polymeric resins reinforced with uniaxially-orientated, high-performance ductile fibers. The various mechanisms of failure taking place during these tests are now investigated with several microscopic techniques, taking cross-sections of samples cut at different angles to the fibre direction. The contribution of shear, compression and tension, as well as the actual location of the failure in relation to the reinforcement and the matrix phases are all readily characterised and visualised. Sub-surface micrography is introduced as an extension of interference contrast incident light microscopy. For suitable samples the technique provided information hitherto unavailable with standard observation methods.