Interfacial Characteristics of Carbon-Epoxy Composites

The interfacial characteristics of the carbon fiber/epoxy matrix composites have been characterized experimentally for fibers with different surface treatments, i. e. , sized and unsized fibers. For the unidirectional composites, double cantilever beam tests were performed to measure the fracture toughness of the material which is influenced by the degree of the fiber/matrix bonding. The short beam shear test yielded the values for apparent interlaminar shear strength. Dynamic mechanical tests were conducted to measure the loss modulus and tan delta as a function of frequency and temperature. The results for energy dissipation (tan delta ) in the dynamic mechanical mode have been compared with the energy absorbing capacity (fracture toughness) of the composite in a static testing mode