Preparation And Properties Of Self-lubricating POM Composites With Improved Thermal Conductivity

The various sliding parts, such as bearing, lead rail, slide plate and piston ring, have a wider application owing to the rapid development of modern machine, electronic industry and armamentarium. With the continuous improvement of high technology, the precision instruments, electronic and electrical products and all kinds of industry machines have developed to be smaller, lighter, high-performance and faster. The conditions of power transmission have been more and more severe. Therefore, the development and application of self-lubricating materials with improved thermal conductivity is of great importance. In this paper, the self-lubricating POM composites with improved thermal conductivity were prepared by incorporation of copper powder and solid lubricants via extruding method. The solid lubricants were PTFE and PFAMAE grafted polyethylene which was prepared by UV-induced surface graft polymerization. The effect of copper and solid lubricants on thermal conductivity and tribological properties of POM composites were studied.1. The thermally conductive POM/Cu composites were prepared by extruding. The effect of copper particles on thermal conductivity and tribological properties of POM composites were studied. The results indicated that the thermal conductivity of composites was increased with the copper content increasing when copper content was above 7.3vol%. The addition of copper particles not only improved the thermal conductivity but also reduced the friction coefficient of composites. However, the wear rate was increased.2. POM/Cu composites were modified by solid lubricant PTFE. The effect of PTFE on the thermal conductivity and tribological properties of materials were studied. The thermal conductivity model and wear mechanism were discussed. The incorporation of PTFE has little effect on the thermal conductivity of composites compared with that of POM/Cu, but reduced the friction coefficient and wear rate. The wear mechanism of POM/Cu/PTFE composites was adhesive wear and abrasion wear.3. The new solid lubricant was successfully developed by grafting PFAMAE onto polyethylene chains via UV-induced surface graft polymerization. The effect of this lubricant on the tribological properties of POM composites was studied. The results indicated that the incorporation of PE-g-PFAMAE improved the compatibility between POM and PE and tribological properties of composites. The uniform lubricating layer was formed during sliding which reduced the wear of materials. The wear mechanism of PE-g-PFAMAE lubricated composites was adhesive wear and abrasion wear.4. The POM/Cu composites lubricated by HDPE-g-PFAMAE were prepared. The effect of HDPE-g-PFAMAE on the thermal conductivity and tribological properties of composites was studied, which was also compared with that of PTFE. The results indicated that the dispersion of fillers in HDPE-g-PFAMAE lubricated composites was better. The distance among the particles decreased which was helpful for the formation of conductive pathways. The addition of HDPE-g-PFAMAE not only reduced the friction coefficient and wear rate of composites but also improved the thermal conductivity. The effect of HDPE-g-PFAMAE on lowering the friction of materials was similar to that of PTFE, but better than PTFE on improving the wear resistance and mechanical properties. The addition of HDPE-g-PFAMAE reduced abrasion wear of materials. The wear mechanism was mainly adhesive wear.