Novel preparation of nano-SiO2 core-shell hybrid inorganic-organic sizing agents for enhanced interfacial and mechanical properties of carbon fibers/epoxy composites

Abstract

The interfacial properties of carbon fibers (CFs) composites were improved by modifying the self-emulsifying amphiphilic epoxy sizing agent with nano-SiO2 particles. Herein, a series of inorganic–organic nano-SiO2 core-cationic epoxy shell hybrid sizing agents (referred to as nano-SiO2 core–shell hybrid sizing agents) with various nano-SiO2 contents were synthesized and used to enhance the mechanical properties of CF/EP. The study indicated that the nano-SiO2 core–shell hybrid sizing agents had the characteristics of the perfect core–shell structure, single dispersion, particle sizes controllable, good storage and high heat resistance. Nano-SiO2 core–shell hybrid sizing agents significantly increased the surface roughness and the surface energy of CFs compared to the unmodified sizing agent. Nano-SiO2 core–shell hybrid sizing agents (7.2% SiO2) increased ILSS, IFSS by 16.92%, 21% and nano-SiO2 core–shell hybrid sizing agents (5.8% SiO2) increased tensile force of monofilament CF by 23.78%, respectively, compared with the unmodified agent. These reinforcements may have been caused by the enhancement of the stress transference of nano-particles in the interface between CFs and EP through an interlocking mechanism. As a result, the nano-SiO2 core–shell sizing agent overcomes the lack of adhesion of traditional nano modification methods and shows remarkable adhesion properties.