Highly improved interfacial affinity in carbon fiber-reinforced polymer composites via oxygen and nitrogen plasma-assisted mechanochemistry

Compounding polymers with carbon fibers (CFs) is a highly effective means of producing polymer composites with enhanced mechanical properties. However, in most conventional carbon fiber-reinforced polymer (CFRP) composites, mechanical improvements are limited by low interfacial affinity between the polymer and the CFs. The plasma-assisted mechanochemistry (PMC) process described herein resulted in covalent bonds between the polymer matrix and CFs, greatly increasing the interfacial affinity between the two materials and allowing the efficient transfer of stress from the polymer to the CFs. Polyketone (PK) and CFs were compounded via PMC processing under O-2, N-2, and Ar plasmas, and carbon nanotubes (CNTs) were introduced at the PK/CF interface. The resulting PK/CNT/CF composites exhibited significantly improved mechanical properties, especially when treated with O-2 and N-2 plasmas. The tensile strength and Young's modulus of O-2 plasma-treated composites increased by 20% and 31%, respectively, compared to those of conventional composites. This approach is generally applicable to the development of high-performance CFRP composites.