Molecular Dynamics Simulation of Pyrolysis and Electric-caused Disintegration Mechanism of Polyphenylene Sulfide

Polyphenylene Sulfide (PPS) has good thermal stability and electrical properties, and is often used in the insulation of electrical equipment such as transformers. Taking PPS as the research object, this paper adopts reactive molecular dynamics simulation based on reactive force field (ReaxFF) to study pyrolysis and electric-caused disintegration mechanisms of PPS at the microscopic level. The results indicate that thioether bond (C-S bond) and delocalized π bond (C-C bond) are respectively the first to break under high temperature and high electric field intensity. The cleavage of chemical bonds leads to the decrease of polymerization degree, which is the main cause for PPS insulation aging. The products of PPS molecules under high temperature and electric field are basically similar, including C2H2, H2S and etc. These gas products will accumulate inside the PPS and generate micropores, which may result in partial discharge and further damage to the insulation of PPS. We found the electric field stresses and deforms PPS molecules by weakening the van der Waals force of the polymer system. The decrease of degree of polymerization (DP) rapidly deteriorates the resistance of PPS chains to high electric field intensity, which leads to structural damage and further insulation damage of PPS material.