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Molecular dynamics simulation of thermal degradation of silicone grease using reactive force field
Author(s) -
Wei Xinyu,
Xu Chi,
Jia Zhidong,
Wang Xilin
Publication year - 2021
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.50203
Subject(s) - grease , reaxff , polydimethylsiloxane , silicone , materials science , chemical engineering , thermal decomposition , oxygen , degree of unsaturation , degradation (telecommunications) , molecule , polymer chemistry , composite material , organic chemistry , chemistry , computer science , engineering , telecommunications , hydrogen bond
Silicone grease, consisting of polydimethylsiloxane (PDMS) chains and silica, has been widely used in electrical power systems; this causes thermal aging of silicone grease at high temperatures. In this study, the thermal degradation process of silicone grease was analyzed at different temperatures using reactive force field (ReaxFF). The effects of different factors, such as silica surface chemistry and oxygen content, on the final products have been studied. The results showed that the final products can be divided into two main categories: small gaseous molecules and large‐molecule products. The number of gaseous hydrocarbon products and their unsaturation increased with increasing temperature. The large‐molecule products were consisted of silica and surrounding PDMS chains, which were broken and reorganized during the thermal degradation process. The time interval required for the formation of the large‐molecule products is larger when silica with a modified surface is used. The addition of oxygen during thermal degradation provided a new decomposition route. The O/Si ratio in the residue of silica grease increased while the C/Si ratio decreased with the increasing oxygen content. A new method for the generation of SiO 2 residues in a sufficient oxygen environment was proposed based on the reactions between oxygen and Si–CH 3 .