Carbon fibre/epoxy composites: Effect of epoxy network and surface treatment of fibres on interfacial shear strength

The paper deals with studies on interfacial shear strength (tau) of carbon fibre composite using single fibre fracture test. Surface modification of desized carbon fibres has been done by argon or oxygen plasma. The effect of network structure on tau has been studied by using difunctional or multifunctional epoxy resins. Interfacial shear strength depends on (i) chemical structure of the epoxy resin (ii) nature of gas used in plasma generation and (iii) duration of plasma treatment. An increase in cross-link density resulted in a decrease in tau, thereby indicating that a more flexible interface is superior for better adhesion with fibres. Oxygen plasma treated carbon fibres gave highest values of tau.