Hierarchical carbon fiber‐SiO2 hybrid/polyimide composites with enhanced thermal, mechanical, and tribological properties

Hierarchical carbon fiber‐SiO 2 hybrid (CF‐SiO 2 ) was first fabricated and CF‐SiO 2 /polyimide composite (CF‐SiO 2 /PI) was subsequently prepared by typical solution casting and thermal imidization. The microstructure and enhancement of CF‐SiO 2 hybrid on the thermal, mechanical, and tribological properties of PI were investigated. Results showed SiO 2 particles with the size of ∼500 nm were coated onto CF surface successfully, which endowed CF possessed active sites and high surface roughness. The 5% weight loss temperatures ( T –5 wt% ) of PI was improved from 328.6°C to 499.2°C by the incorporation of CF‐SiO 2 hybrid. Besides, the hardness and elastic modulus of CF‐SiO 2 /PI composite reached 0.411GPa and 4.904 GPa, that is, an improvement of 22% and 12.2%, respectively, compared to pure PI. More importantly, the friction coefficient and wear rate of CF‐SiO 2 /PI reached 0.32 and 5.35 × 10 −5 mm 3 /Nm, which were much lower than that of PI or CF/PI. This was mainly attributed to the fact that SiO 2 could not only improve the thermal and mechanical properties but also promote the load transferring effectively during the friction and wear process through enhancing the interfacial effect between CF and PI. POLYM. COMPOS., 39:E1626–E1634, 2018. © 2017 Society of Plastics Engineers