Characterization of interfacial bonding property of carbon fiber/epoxy resin using single fiber fragmentation test with dual matrix composites

The dual matrix method in single fiber fragmentation test (SFFT) was established which made it possible to obtain the saturated breakpoints of the single fiber embedded in the inner layer brittle resin because of the protection of the outer layer ductile resin. The matrix with low elongation can be used in this method to obtain interfacial shear strength, where conventional SFFT can not work in this case. Interfacial shear strength and interfacial fracture energy were used to investigate carbon fiber/epoxy resin interfacial properties under dry and water aging conditions. Two kinds of T300 grade carbon fiber as well as two types of T800 grade carbon fiber were adopted. The interfacial fracture energies obtained from dual matrix sample and single matrix sample were compared. The results show that the qualitative changes of interfacial adhesion of carbon fiber/epoxy resin in the dual matrix method and single matrix method are similar. The interfacial fracture energy and interfacial shear strength of dual matrix sample can be used to evaluate the moisture resistance of interfacial property, and the changes of the two parameters are consistent. The interfacial adhesions of all studied carbon fiber/epoxy resin decrease after water aging, and the interfacial properties of imported carbon fiber systems are greater than those of national carbon fiber systems.