【作者】 李科；

【导师】 向定汉；

【作者基本信息】 南京航空航天大学 ， 材料学， 2008， 硕士

【摘要】 随着人们对生态环境的日益重视,材料和产品的可回收性、环境友好性等问题变得越来越重要。聚甲醛（POM）是一种综合性能优良的广泛使用的自润滑工程材料,然而,目前使用的POM自润滑材料多数含有聚四氟乙烯（PTFE）、MoS2等填充材料,在其废弃回收过程中将不可避免的造成环境污染（例如,它们中很大一部分通过焚烧处理,氟、硫将进入大气层,危害环境和人类健康）。因此,寻找这一类填充材料的替代品具有重要意义。本研究选用低密度聚乙烯（LDPE）和稻壳粉（RHF）作为填充材料,希望在保持POM优异性能的同时,降低成本,实现POM自润滑材料的绿色化。通过挤塑和模压的方法制备了一系列POM复合材料,对其进行力学性能和摩擦磨损性能测试,结果表明:复合材料POM+5wt.%LDPE表现出较好的综合机械性能和摩擦磨损性能。在此基础上,进一步添加稻壳粉,性能测试结果表明:复合材料POM+5wt.%LDPE+7.5wt.%RHF具有最低的磨损率1.07×10^-6 mm³/N·m,比纯POM提高了近50%,同时又保持了较低的摩擦系数和良好的综合机械性能。与商用POM自润滑材料和木质素纤维增强POM复合材料的对比实验表明:以LDPE替代PTFE,以稻壳粉作为天然纤维对POM进行改性是可行的。本项研究表明:复合材料POM+5wt.%LDPE+7.5wt.%RHF表现出较好的综合机械性能和摩擦摩擦性能,同时具备了环境友好、低成本特性,是一种具有潜在应用价值的绿色环保自润滑材料。更多还原

【Abstract】 Ecological and environmental concern has recently attracted more and more attention, and issues such as recyclability and environmental safety have become increasingly important for the introduction of new materials and products. Polyoxymethylene （POM） is one of the mostly used self-lubricating engineering plastics, which exhibites excellent mechanical and tribological properties. However, most of the POM products include fillers such as PTFE, MoS2, which will exert unfavorable impact on our environment at the end of their life cycle because of the existence of fluorine or sulfur. So it is of great significance to find other materials as substitutes for these traditional fillers while maintaining the excellent properties of POM products. In this study, Low-density polyethylene （LDPE） and rice hull flour （RHF） were selected as the fillers, aiming to produce a green POM composite which is well-performing and low-cost.POM composites filled with various content of LDPE and RHF were prepared by extrusion and compression molding. The tests of mechanical and tribological properties were carried out. Results showed that the composite POM+5wt.%LDPE exhibited a good combination of mechanical and tribological properties. On this basis, RHF was further incorporated into POM composites. It was found that the composite POM+5 wt.% LDPE+7.5 wt.% RHF exhibited the lowest wear rate 1.07×10^-6 mm³/N·m （a reduction of 50% when compared to that of POM）, while maintaining a low coefficient of friction and good mechanical properties.In the meantime, POM composites filled with LDPE and Wood Cellulose Fiber （WCF） and other two commercialized POM composites were prepared. A comparative investigation between these POM composites showed that, it was feasible to produce a self-lubricating POM composite filled with LDPE and RHF.It was experimentally confirmed that, the composite POM+5 wt.% LDPE+7.5 wt.% RHF, which is well-performing, low-cost, and environmentally friendly, would be a potential self-lubricating material for practical application.更多还原