Graphite fluoride and fluorographene as a new class of solid lubricant additives for high-performance polyamide 66 composites with excellent mechanical and tribological properties

Fluorographene (FG) with layer numbers of 3-4 was successfully prepared through facile microwave-assisted liquid phase exfoliation of raw graphite fluoride (GrF). The raw GrF and the as-prepared FG were then directly incorporated into polyamide 66 (PA66) by melt processing without using any surfactants. Microstructural, mechanical and tribological properties of the prepared PA66 composites were investigated. Various characterization results showed that both GrF and FG, as novel solid lubricants, can effectively improve the mechanical and anti-wear performances of the PA66 matrix. It was also found that FG is better at improving mechanical properties and reducing the friction of PA66 than GrF at low concentrations owing to the large surface-volume ratio. The addition of 0.5 wt% FG into PA66 exhibits a ca 13% increase in tensile modulus, ca 5% increase in tensile strength, ca 18% reduction in coefficient of friction (COF) and ca 43% reduction in wear rate. However, at relatively high concentrations, such as 1.0 wt%, GrF shows a better reinforcement effect than FG owing to a uniform dispersion of GrF in the PA66 matrix. The addition of 1.0 wt% GrF into PA66 exhibits a ca 18% increase in tensile modulus, ca 5% increase in tensile strength, ca 37% reduction in COF and ca 46% reduction in wear rate. Wear tests also show that the excellent wear resistance of the PA66 composites is due to the improved mechanical properties and the lubrication of GrF and FG between the worn surfaces. Our current work demonstrates the tremendous potentials of fluorinated carbon materials for enhancing mechanical and anti-wear properties of polymeric materials. (c) 2020 Society of Chemical Industry