Development of Antifriction Materials Based on Polytetrafluorethylene with Carbon Fibers
Investigation the effect of small additions of ultradisperse polytetrafluoroethylene on the physico-mechanical and tribotechnical properties of polytetrafluoroethylene and composites based on it, filled with carbon fibers. Adding ultradisperse polytetrafluoroethylene to the binary system "polytetrafluoroethylene-carbon fibers" leads to an increase in the wear resistance of the composition to 271 times, a reduction in the coefficient of friction compared to the initial polymer, while maintaining of strength and strain characteristics at the level of polytetrafluoroethylene. To explain this change in the properties of polymer composite materials, structural studies have been carried out using X-ray diffraction analysis and scanning electron microscopy. Structural studies on an X-ray powder diffractometer showed when the ultradispersed PTFE is introduced into the polymer matrix, the average crystallite size increases, with additional introduction of carbon fibers, the crystallite sizes decrease. Modification with carbon fibers leads to the formation of a more organized structure, the degree of crystallinity of composites is higher than that of the original PTFE. A high degree of crystallinity has a composite containing 3 wt.% of carbon fibers. The supramolecular structure of polytetrafluoroethylene is characterized as a tape. Raster electron microscopy has shown that the introduction of carbon fibers into the polymer matrix changes the nature of the supramolecular structure of the composites. The formation of a loose supramolecular structure of composites with a random distribution of fibers in the volume of the polymer is observed.