| As a thermoplastic, PTFE is famous as "The King of Plastic", with excellent chemical stability and lubricative properties, has been widely used as antiseptic or friction materials. However, PTFE exhibits poor wear resistance and mechanical properties which may hold back its extensive applications. Many methods, such as filling modification, surface modification and mixing modification, were used to improve PTFE properties in recent years. In the study, the method of filling modification, with glass fibers, carbon fibers or graphites as reinforcing component, was used to prepare PTFE composites. The effect of the composition ratio on PTFE composites properties was analysised and the reinforcing mechanism was also investigated.Carbon fibers and glass fibers were treated by coupling agents and the treating process was considered through the friction and wear test. The result shows that the wear resistance of PTFE composites could be improved significantly when glass fibers suffered coupling treating. However, as for carbon fibers, the improvement of wear resistance appeared slightly.The friction and wear properties of pure PTFE and PTFE composites were determined. Surface microstructure was examined through scanning electron microscopy (SEM). The friction mechanism of PTFE composites which reinforced by glass fibers, carbon fibers or graphite was studied. The result indicates that glass fibers and carbon fibers embedded in matrix preferentially support the load and pass the pressing stress and shearing strength into inside area to avoid stress concentration on wear surface. These fibers are effective in preventing the large-scale fragmentation of PTFE and in improving the wear resistant. However, fibers would enrich on the wear surface, leading to high friction coefficient. At the same time, fibers may shed off and cause particle abrasion. Graphite could form a lubricative film on the wear surface, reducing friction coefficient and improving wear resistance. The friction, which fibers bearing, could be reduced due to the existence of graphite which functioning as a lubricant. So, those fibers could be prevented from shedding off. The relationship, between friction coefficient and glass fibers content of composites reinforced by glass fibers and graphite, is different from the composites reinforced only by glass fibers. It means that glass fibers and graphite cooperate with each other, appearing lubricating effect. Composites, reinforced by glass fibers, graphite and carbon fibers, have better properties of friction and wear. The mechanical and thermal mechanical properties of pure PTFE and PTFE composites were studied through the tests of tensile, impact, hardness, compress, thermal mechanical bending and compressing distortion. The result shows that the filling of glass fibers increased compress strength, hardness, and improved the thermal mechanical bending properties, while decreased tensile and impact strength, deteriorated the thermal mechanical compressing properties, and the composites is brittle. The filling of carbon fibers increased tensile strength, compress strength, hardness and improved the thermal mechanical properties, while decreased impact strength, and the composites is also brittle. Graphite enhanced the compress strength and improved the thermal mechanical properties, while decreased the hardness, tensile strength and impact strength. PTFE composites, reinforced by glass fibers, carbon fibers and graphite, has properties of better tensile strength, compress strength, hardness and better thermal mechanical properties. Though the impact strength decreased, it is also tough composites.The following conclusions could be drawn that the PTFE composites reinforced by glass fibers, carbon fibers and graphite has better wear properties and general mechanical properties, as well as better thermal mechanical properties. The best ratio of raw materials is, PTFE: glass fibers: carbon fibers: graphite = 70:20:5:5 (ratio of weight).
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