Properties of surface-modified CF reinforced PTFE composites

The carbon fiber （CF） was surface-modified using silane coupling agent and fluorinating agent. The silanized CF （K-CF） and silane-fluorinated CF （KF-CF） reinforced polytetrafluoroethylene （PTFE） composites were prepared. The microstructure and elemental analysis of the surface-modified CF were carried out. The thermal properties, mechanical properties and tribological properties of surface-modified CF-reinforced PTFE composites were studied. The results show that silanization treatment formed a silane compound film on the surface of CF, enhancing the interfacial adhesion between CF and the PTFE matrix. Fluorination treatment introduced fluorine-containing functional groups, the interfacial bonding performance was improved through the interaction between fluorine atoms and aromatic rings. Compared with CF reinforced PTFE composites, the glass transition temperature of K-CF and KF-CF reinforced PTFE composites increased, the coefficient of thermal expansion decreased, the compressive yield strength, tensile strength and percentage elongation after fracture increased, the coefficient of friction improved, the volume wear rate decreased, and the thermal stability, mechanical properties and wear resistance were significantly enhanced. The modification effect of silane-fluorination treatment was the best. Compared with CF reinforced PTFE composites, the compressive yield strength, tensile strength and percentage elongation after fracture increased by 26.1%, 22.6% and 28.5% respectively.