Reduction Of Graphite Oxide And Study On The Properties Of GO/PTFE Composites

Graphene with single layer graphite structure and excellent mechanical and electrical properties has draw much attention in recent years. Even though there are many methods for the preparation of graphene, reduction of graphite oxide (GO) is accepted as one of the most important methods. In this dissertation, we first investigated a fast, economical and green method to prepare reduced GO (R-GO), and then prepared R-GO/poly(tetrafluoroethylene)(PTFE) and CNT/PTFE nanocomposites and investigated the tribological properties.Infrared (IR) irradiation is a heating method by electromagnetic waves, with non-contact, high energy transferring speed and high transferring efficiency. In the first chapter of this dissertation, a bathroom IR lamp was used as the source of the IR light (wavelength0.78-4μm) for the photothermal reduction of GO. It was found that the reduction of GO powders or films is rapid and fierce at high IR power density. The reduction accomplishes within several tens of seconds or minutes, with fierce degassing phenomenon. Besides, power density of the IR irradiation was found to greatly influence the structure and properties of R-GO; the lower the distance, the higher the conductivity and the reduction speed. Raman, FT-IR, UV-Vis-IR spectroscopy and XPS were used to characterize the structure of GO and R-GO. It was found that the hydroxyl and carboxyl groups were removed after reducing GO, and C/O ratio was in the rage of7.7-8.3, the loss weight at600℃was11-16%, the volume conductivity was as high as1670S/m.PTFE presents low friction coefficient, high heat resistance and low surface energy. Unfortunately, it usually exhibits a poor wear resistance, low hardness and poor thermal conductivity, which limit its applications. Various kinds of reinforcing fillers have been developed to improve the tribological behaviors of PTFE-based composites. In the second chapter of this dissertation. GO/PTFE nanocomposites were prepared by blending GO suspension and PTFE emulsion. It was found that R-GO could be well dispersed in the GO/PTFE composites after sintering. Meanwhile, the composites exhibit an excellent electrical conductivity at an electrical conductivity percolation threshold as low as below1wt%, and addition of R-GO improves resistance to wear remarkably. The wear rate of GO/PTFE was better than CNT/PTFE composites at the same filling contents.