不同官能团修饰碳纳米管填充PP复合材料分子模拟

Molecular simulation of PP composites modified by carbon nanotubes with different functional groups

随着光伏发电和海上发电等新型清洁能源的迅速发展,对薄膜电容器的工作温度提出了更高的要求。然而,当前使用最泛的双向拉伸聚丙烯(BOPP)电容器薄膜在高温以上时无法胜任应用需求。基于实验与仿真的方法,对聚丙烯(PP)、碳纳米管及羟基、氨基、羧基功能化碳纳米管(CNTs-COOH)填充PP复合体系进行热重试验、玻璃化转变温度、热导率、自由体积分数和均方位移等性能的研究。结果表明,经羧基修饰的碳纳米管与PP复合后的热学性能增加效果最为显著,氨基、羟基修饰的碳纳米管体系次之。CNTs-COOH复合材料具有更优异的性能,其起始热分解温度和玻璃化转变温度分别提高了76.15℃和40.33℃,热导率较纯PP体系提高了18.27%,自由体积分数降低至17.96%。羧基的加入能够有效占据PP/CNTs复合体系中的空穴,减缓复合体系分子链段的移动和降低复合体系的均方位移,使得PP复合体系保持良好的热稳定性。研究结果可为适用于高温条件的PP电容器薄膜材料提供参考。

With the rapid development of new clean energy sources such as photovoltaic power generation and offshore power generation,higher operating temperatures are required for film capacitors.However,the most widely used biaxially oriented polypropylene(BOPP)capacitor films are not capable of meeting the application requirements above high temperatures.The properties of PP,carbon nanotubes(CNTs),and PP composites modified by carbon nanotubes with hydroxyl,amino,and carboxyl functional groups were investigated based on experimental and simulation methods,such as thermo gravimetric tests,glass transition tempera‐tures,thermal conductivities,free volume fractions,and mean square displacements.The results show that the carboxyl-modified CNTs composite with PP show the most significant increase in thermal properties,followed by the amino-and hydroxyl-modified carbon nanotubes systems.The CNTs-COOH composites have superior properties,with an increase in onset of thermal decomposi‐tion and glass transition temperatures of 76.15℃ and 40.33℃,respectively,and an increase in thermal conductivity by 18.27%compared to the pure PP system,and the free volume fraction was reduced to 17.96%,while the free volume fraction is reduced to 17.96%.The addition of carboxyl groups can effectively occupy the cavities in the PP/CNTs composite,slow down the movement of the molecular chain segments of the composite system and reduce the mean square displacement of the composite system,so that the PP composite system maintains a good thermal stability.The results of the study can provide a reference for the PP capacitor film materials suitable for high-temperature conditions.