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Pyrolysis kinetics of highly crosslinked polymethylsiloxane by TGA
Author(s) -
Li Dong,
Hwang SunTak
Publication year - 1992
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.1992.070441113
Subject(s) - thermogravimetric analysis , activation energy , pyrolysis , inert gas , kinetics , materials science , isothermal process , chemical engineering , nitrogen , oxygen , chemistry , polymer chemistry , composite material , organic chemistry , thermodynamics , physics , quantum mechanics , engineering
The pyrolysis kinetics of highly crosslinked polymethylsiloxane (PMS) was investigated by thermogravimetric analysis (TGA) under both isothermal and elevated temperature conditions with several environmental gases, such as oxygen, nitrogen, air, and helium. A non‐chain‐scission mechanism composed of initiation, propagation, and termination was proposed to interpret the thermal degradation of highly crosslinked PMS. The mechanism was verified by the experimental results under isothermal conditions. The activation energy of initiation, E i , was about 20–30 kcal/mol and the activation energy of propagation, E p , was about 4–6 kcal/mol. These activation energies were found to be different for different gases. The activation energy of initiation for PMS in an aggressive atmosphere, such as oxygen, was lower than that in an inert atmosphere, such as nitrogen. But the activation energy of propagation for PMS was higher in an active environment than in an inert one. There were no direct conclusions about the thermal degradation of highly crosslinked PMS at elevated temperature. Based on thermogravimetric experiments, it is suggested that a pyrolysis process be conducted with a rate of temperature increase less than 10°C/min for preparing the silicon base inorganic membrane.