Molecular simulation of PP composites modified by carbon nanotubes with different functional groups
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 polypro-pylene(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.
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