Effect of Vacuum Thermal Cycling on Mechanical and Physical Properties of an Epoxy Matrix Composite

Abstract

Mechanical and physical properties of a unidirectional carbon fiber reinforced epoxy matrix (T700/3234) composite have been evaluated after being vacuum thermal cycled (133-413 K, 10-3Pa) up to 300 cycles. The fracture surface morphology of the tested specimens was examined by SEM. It was shown the mass loss ratio of either the composite or the epoxy matrix increased with increasing thermal cycles and then leveled off after 50 cycles. The tensile strength at 90º of the composite was found to decrease at the initial stage of thermal cycling, increase after 50 cycles, and tend to level off after about 100 cycles. The results also showed that the interlayer shear strength of the composite was nearly not affected by thermal cycling. It is suggested that debonding of fiber/epoxy interface and post curing in matrix during vacuum thermal cycling should be responsible for evolvement of mechanical properties of the T700/3234 composite.