聚酰亚胺高温裂解机理的反应分子动力学模拟

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Abstract Polyimide, due to its excellent insulation properties, has been widely used in solid state transformers, frequency conversion motors and other electrical devices, whereas the cleavage of chemical bonds under high temperature is the main reason for the insulation failure. In this paper molecular simulation method based on reactive force field (ReaxFF) is introduced to carry out reactive molecular dynamics simulation on PI molecular models and to investigate its pyrolysis mechanism at high temperature in the atomic level. Polyimide with 4 monomers is taken as the example to simulate and analyze the initial pyrolysis mechanism, micro dynamic reaction paths during the whole process, the formation mechanism of main products. The microscopic insulation failure mechanism under high temperature is then obtained. The results indicate that initial breaking bond is the C-N bond on the imide ring, and the cleavage of C-N bond connecting two benzene rings is the main reason for PI main chain scission. CO₂ and CN are the major products of PI pyrolysis, and their formations are both associated with the cleavage of C-N bond on the imide ring; the reduced degree of polymerization of PI main chain, CO₂ and other small molecules generated by the scission of imide ring jointly lead to the insulation failure of PI at high temperature.

Key words： Polyimide ReaxFF high temperature pyrolysis microscopic mechanism reactive molecular dynamics the cleavage of chemical bonds

Received: 28 July 2014 Published: 12 July 2016

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TM215.1

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https://dgjsxb.ces-transaction.com/EN/ OR https://dgjsxb.ces-transaction.com/EN/Y2016/V31/I12/14

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