Surface Modification Of Carbon Fiber And Interfacial Adhesion Study Of Carbon Fiber/Rubber Composites

In recent years, carbon fiber is extensively being used as high performance fiber for its excellent properties such as high strength-weight ratio, heat resistance and chemical resistance. And carbon fiber reinforced composites have been widely used in spacecraft, medical devices, sport equipment and many other fields. As we know, the interface plays a critical role in controlling the overall properties of the composites. However, carbon fiber suffers from an inert surface, which may results in a weak interfacial interaction between fiber and matrix. In the past decades, a large amount of carbon fiber/rubber composites have been used in military and industry fields. Thus, it is crucial to improve the interfacial adhesion of carbon fiber with rubber matrix. Herein, a novel dopamine-based modification was used in this study to improve the property of carbon fiber surface. This method is high-efficiency and co-friendly without sacrificing the mechanical properties of carbon fiber. Silane coupling agents were also used in this study due to their outstanding adhesion with rubber.(1) The surface treatment of carbon fiber by dopamine was conducted. The influence of dopamine concentration, reaction time and temperature on the grafting efficiency was studied and the optimal reaction condition was 1.5 g/L,4 hours,30℃, respectively.(2) Thereafter, y-(methacryloxy)propyltrimethoxysilane (KH570) was applied for secondary functionalization, introducing carbon double bonds on carbon fiber surface which result in 172% increase of the adhesion property. The influence of KH570 concentration, reaction time and temperature on the grafting efficiency was also studied. Results showed that the optimal reaction condition was 4.0 wt.% KH570 reacted under 60℃ for 8 hours. In addition, the modified samples exhibited thermal and oxidative aging resistance.(3) For comparison, other silane coupling agents including y-(2,3-epoxypropoxy)propytrimethoxy silane (KH560), y-(Amino)propyltri-ethoxysilane (KH550) and bis-(y-triethoxysilylpropyl) (Si69) were used to functionalize the PDA deposited carbon fiber. Epoxy, amino and sulfide groups were introduced to the surface of carbon fiber respectively. Compared with that of pristine carbon fiber, the pull out force of KH560, KH550 and Si69 modified carbon fibers were increased by 108.9%,117.9% and 132.4% respectively. The possible mechanism was demonstrated in the chapter.