Learning from nature: Constructing “rigid-soft” structure on carbon fibers surface by self-assembly to improve the performance of epoxy composites

The firm interface phase played an important role in influencing the comprehensive performance of carbon fiber reinforced polymer composites (CFRP). To increase the interfacial adhesion between fiber and epoxy resin, a “rigid-soft” structure consisted of boron nitride (BN) and soybean meal (SM) was constructed on CF surface by self-assembly method. The structure was beneficial to form a stress buffer area between CF and matrix, which would prevent crack propagation and brittle fracture of composites, as well as the stress concentration. The interlaminar shear strength (ILSS), interfacial shear strength (IFSS) and flexural strength of modified CF composites presented 44.2%, 77.9% and 52.5% increment, respectively, compared with pristine composites. The thermal conductivity was also increased by 148.5% after modification due to the excellent heat conductivity of BN and enhancement of interfacial bonding. This work was expected to offer a valuable reference for achieving outstanding properties of CF composites in the future.