Spectroscopic study of a model composite: Compressive behavior of the reinforcement fiber and the buildup of thermal residual stress

Abstract

AbstractThe compressive behavior of polydiacetylene (PDA) single‐crystal fiber and the buildup of thermal residual stress in PDA/epoxy model composite systems have been studied by Raman‐mechanical spectroscopy. The compressive failure of the PDA fiber has been directly observed when the macroscopic compressive stress, applied during a bending experiment, exceeds a critical value. Fiber failure in model composites caused by thermal residual stress can also be observed by Raman measurements as well as optical microscopy. In fact, the most clear indication of fiber failure was the observation of kink bands formed. The thermal residual stress buildup which resulted from significant temperature changes in this model composite have also been studied. Contrary to most accepted views, our analysis showed the adhesion between the reinforcement fiber to the epoxy matrix to be strong.