ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
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, Ei, was about 20-30 kcal/mol and the activation energy of propagation, Ep, 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.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1992.070441113
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