Correlation of temperature dependences of macro- and micro-interfacial properties in carbon fiber/epoxy resin composite

The short beam shear test and single fiber fragmentation test with an energy-based model were conducted to characterize the interfacial properties of two types of carbon fiber-reinforced epoxy resin composites. The temperature dependences of interlaminar shear strength and interfacial fracture energy (Gamma(i)) from room temperature to 130 degrees C were investigated. The correlation between interlaminar shear strength and the micro-interfacial property at elevated temperature was discussed. The scanning electron microscope images of fractographic cross-sections of the composite laminates were used to analyze the failure mode transition as the temperature rising. The results show that the interfacial properties of the two carbon fiber composites with the same matrix are obviously different, especially at high temperature. The changes of interlaminar shear strength and interfacial fracture energy are different at elevated temperature, mainly ascribed to the different treating ways of thermal residual stress and matrix property in the two methods. The similar temperature sensitivities in the changes of Gamma(i) and the amount of matrix adhering on carbon fibers in the short beam shear failure images suggest the variations of the micro-interfacial properties in the short beam test as increasing temperature.