共聚共混改性聚酰亚胺的摩擦磨损性能研究

摘要

In order to improve the friction properties of the traditional PMDA–ODA polyimide (PI),the aromatic heterocyclic diamine (DAMI) was introduced by copolymerization and blending respectively,then the PI materials modified by copolymerization and blending were prepared in modifying molecular structure with different mole rate of ODA/DAMI. The structure and properties of the modified PI materials were analyzed by friction and wear tester,SEM,FTIR,universal testing machine and X-ray diffraction. The results show that when the mole rate of ODA/DAMI is 3∶1 and 5∶1 respectively,the PI modified by copolymerization and blending all have best comprehensive tribological and wear properties,the friction coefficient is 0.273 and 0.280 respectively,the wear rate is 9.28×10–14,11.2×10–14 m3/(N·m) respectively,the friction coefficient change of the former is more stable than that of the latter with the increase of friction time and has more advantages in balancing friction coefficient and wear rate. The wear mech-anisms of the two modified PI materials are similar and mainly adhesive wear,abrasive wear and fatigue wear. The tensile strength, modulus and glass transition temperature of the two modified PI materials are declined with increasing DAMI content. When DAMI content is higher,crystallization orientations of the two modified PI materials increase and the wear rates rise suddenly.%为了改善传统均苯四甲酸酐(PMDA)–4，4′-二胺基二苯醚(ODA)型聚酰亚胺(PI)的摩擦性能，分别以共聚和共混两种方式，引入柔性二胺单体芳香杂环二胺(DAMI)，从分子结构制备不同ODA／DAMI物质的量之比的共聚和共混改性PI。并用摩擦磨损试验机、扫描电子显微镜、万能试验机以及X射线衍射仪等分析共聚和共混改性PI的结构和性能。结果表明，当ODA／DAMI物质的量之比分别为3∶1和5∶1时，共聚和共混改性PI具有最优的综合摩擦磨损性能，摩擦系数分别为0.273和0.280，磨损率分别为9.28×10–14，11.2×10–14 m3／(N·m)。共聚改性PI的摩擦系数随摩擦时间的增加变化比较稳定，其在兼顾磨损率和摩擦系数方面比共混改性PI更具优势。共聚和共混法改性PI磨损机理相似，主要为粘着磨损、磨粒磨损和疲劳磨损。随DAMI含量增加，两种改性PI的拉伸强度、拉伸弹性模量和玻璃化转变温度均呈下降趋势，当DAMI含量较高时，两种改性PI结晶取向增加，磨损率急剧升高。