Degradation Reactions in Silicone Polymers.
Final rept. 1 Jul 73-30 Jun 75,
GLASGOW UNIV (SCOTLAND) DEPT OF CHEMISTRY
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This report is concerned with the preparation and thermal degradation of methyl and phenyl substituted siloxane polymers. There are three main experimental sections which are concerned respectively with polydimethyl-siloxane, polydiphenylsiloxane and polyphenylmethylsiloxane. The volatile products of thermal degradation of polydimethylsiloxane at temperatures from 200 C upwards, have been separated and estimated quantitatively using gas-liquid chromatography and shown to consist of cyclic trimer, tetramer, pentamer, hexamer, etc. in decreasing quantities. Infra-red spectral examination of the residual polymer suggests that crosslinking has occurred. At 160 C the molecular weight does not change, at 200 and 250 it increases to approximately double its initial value, while at 300, 350 and 400 C it increases initially but later decreases. The mechanism of thermal degradation of polydimethylsiloxane is discussed in the light of these observations.
- Polymer Chemistry