Single-fiber fragmentations of AS-4 carbon fiber embedded in Epon 828 under the effect of elevated temperatures

Single fiber fragmentation tests were performed over a range of elevated temperatures (ambient to 160°C) to study the effect of temperature on the fiber-matrix interface. In order to understand the mechanical performance of a polymer/carbon fiber composite system, the micromechanical performance must be understood. The mechanical performance of a composite material is dependent on the fiber-matrix interface region. The nature of the fiber-matrix interface controls the interfacial shear strength and this is an important parameter in the formulation of shear-lag and other micromechanical models. Micromechanical shear-lag models are used to estimate macromechanical properties of composite materials. Environmental conditions that affect the macromechanical properties of polymer composites need to be understood at the micromechanical level. Temperature is one example of an environmental condition that influences the mechanical response of some composite systems. The study presented in this paper uses the measurement of broken fiber lengths resulting from the multiple fracture of a single fiber that is embedded in resin with applied load. The material system used in this study was an AS4-carbon-fiber/Epon-828/mPDA-epoxy-resin-system. The critical fragmentation lengths were measured with the aid of a microscope, and the critical lengths were found to increase 70% from ambient temperature to 160°C.