Interfacial adhesion of carbon fiber to special engineering plastics: Effect of the functional groups in the matrix

We studied the interfacial shear strength (IFSS) in carbon fiber (CF) and special engineering plastics matrix, with an emphasis on the effect of the functional group in the matrix. The IFSS was analyzed to quantify the interfacial adhesion between the fiber and the matrix. To obtain the apparent IFSS of the composites, microdroplet test was measured at single-fiber composites. Results of the microdroplet test displayed that the apparent IFSS in the composites was directly determined by their inherent surface properties and the functional groups in the matrix. Compared with other matrices, polyetherimide (PEI) exhibited relatively strong mechanical bonding and interfacial adhesion, showing that the imide groups had good interfacial compatibility with the pristine CF surface. Based on the results of this study, polymers containing imide groups were one of the best candidates for sizing agent of CF used as reinforcement of high-temperature thermoplastics.