填充型聚四氟乙烯复合材料的性能及界面研究

发布时间：2018-05-09 05:31

本文选题：聚四氟乙烯 + 无机填料　；参考：《扬州大学》2017年硕士论文

【摘要】：聚四氟乙烯(PTFE)作为工程塑料的一种,应用十分广泛。但是,其力学、热膨胀、耐磨损性能较差等缺点,极大地限制了其在许多如高温、高压等特殊场合下的应用。因此,如何解决现代工业生产中所遇到的诸如高温下耐磨损等问题,改善PTFE材料的综合性能,是目前值得深入研究的课题。本文分别研究了不同尺寸、形貌及表面性质的无机填料对聚四氟乙烯性能的影响。同时,深入探讨了不同质量比,不同形貌及表面改性对复合材料性能影响及界面作用机制。(1)采用冷压成型及烧结工艺制备出玻璃纤维(GF)和埃洛石(HNTs)填充的PTFE复合材料,研究了填料类型及不同配比的填料对PTFE摩擦学性能、线膨胀系数及力学性能的影响。结果表明:相比GF/PTFE二元体系,适量填充HNTs可以提升GF/PTFE的摩擦磨损、热膨胀及力学性能。填充2wt%HNTs时的HNTs-GF/PTFE三元体系复合材料比GF/PTFE二元体系的磨损率降低32.7%,三元体系的线膨胀系数比PTFE降低近2个数量级,断裂伸长率,拉伸强度和弯曲强度分别提高40.0%,2.3%和7.1%。(2)利用GF、二硫化钼(MoS2)和滑石粉填充改性PTFE材料。通过正交试验发现,GF、MoS2、滑石粉和聚四氟乙烯的最佳配比为2:3:3:92,这时复合材料可以获得较好的力学性能、热膨胀和摩擦学性能。原子力显微镜(AFM)和扫描电子显微镜(SEM)分析结果表明,GF的高温表面化学改性明显改善了其与PTFE基体之间的界面结合。同时,填料与聚合物基体间存在的机械锁合作用,也是PTFE复合材料具有较好综合性能的重要因素。(3)将制备的纺锤形碳酸钙剥离的石墨烯纳米片(CGNPs),作为填料填充PTFE材料。对CGNPs/PTFE复合材料的力学、电学及摩擦学性能进行了研究和讨论,发现填充1wt%CGNPs的PTFE复合材料的拉伸强度和断裂伸长率分别提高了 44%、26%,复合材料的导电逾渗阈值同样为1wt%,当填充量达到10wt%时,复合材料中导电网络基本形成,并且摩擦学性能优异。通过差示扫描量热仪(DSC)、拉曼及微观形貌等测试,探讨了填充不同量CGNPs对复合材料性能的影响。结果表明,CGNPs在聚合物基体中分散均匀,少量的CGNPs可以起到异相成核的作用,改善复合材料的力学性能;另外,CGNPs的独特三维结构以及其与聚合物之间的机械锁合作用是复合材料电学及摩擦学性能优异的主要原因。
[Abstract]:PTFEs are widely used as engineering plastics. However, its mechanical, thermal expansion and poor wear resistance greatly limit its application in many special situations such as high temperature and high pressure. Therefore, how to solve the problems in modern industrial production such as wear resistance at high temperature and improve the comprehensive properties of PTFE materials are worthy of further study. The effects of inorganic fillers of different sizes, morphology and surface properties on the properties of PTFE were studied. At the same time, the effects of different mass ratio, morphology and surface modification on the properties of the composites and the interfacial mechanism were discussed. The PTFE composites filled with glass-fiberglass (GF) and Elostone-HNTswere prepared by cold pressing and sintering. The effects of different filler types and ratios on the tribological properties, linear expansion coefficient and mechanical properties of PTFE were studied. The results show that the friction and wear, thermal expansion and mechanical properties of GF/PTFE can be improved by filling HNTs with proper amount compared with GF/PTFE binary system. The wear rate of HNTs-GF/PTFE ternary composites filled with 2wt%HNTs is 32.7m lower than that of GF/PTFE binary system, the linear expansion coefficient of ternary system is about 2 orders of magnitude lower than that of PTFE, and the elongation at break of the ternary system is about 2 orders of magnitude lower than that of GF/PTFE binary system. The tensile strength and flexural strength were increased by 40. 0% and 7. 1%, respectively.) the modified PTFE materials were filled with GF-, MoS _ 2) and talc powder. The optimum ratio of talc powder to PTFE was found to be 2: 3: 3: 92 by orthogonal test. The composites obtained better mechanical properties, thermal expansion and tribological properties. The results of atomic force microscopy (AFM) and scanning electron microscopy (SEM) show that the surface chemical modification of GF at high temperature obviously improves the interfacial bonding between GF and PTFE matrix. At the same time, the mechanical lock cooperation between filler and polymer matrix is also an important factor for the good comprehensive properties of PTFE composites. The graphene nanoflakes of spindle-shaped calcium carbonate are used as fillers for filling PTFE materials. The mechanical, electrical and tribological properties of CGNPs/PTFE composites were studied and discussed. It is found that the tensile strength and elongation at break of the PTFE composites filled with 1wt%CGNPs are increased by 44% and 26%, respectively. The conductivity percolation threshold of the composites is also 1 wt. when the filling amount reaches 10 wt%, the conductive network is basically formed and the tribological properties are excellent. The effect of filling different amounts of CGNPs on the properties of composites was investigated by means of differential scanning calorimeter (DSC), Raman spectroscopy (Raman) and micro-morphology measurements. The results show that CGNPs are dispersed uniformly in the polymer matrix, and a small amount of CGNPs can play the role of heterogeneous nucleation and improve the mechanical properties of the composites. In addition, the unique three-dimensional structure of CGNPs and the mechanical lock cooperation between CGNPs and polymers are the main reasons for the excellent electrical and tribological properties of the composites.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ327.8;TB332

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