The action of heat on the polyorganosiloxanes derived from the minerals biotite and pseudowollastonite by trimethylsilylation

The polyorganosiloxanes prepared by the trimethylsilylation of mineral silicates contain Q [SiO4/2] units and M [CH3)3 SiO1/2] units. Investigations into the behaviour of these materials in the temperature range 100‐1000°C and for times varying from 2‐64 hours have shown that a variety of reactions take place with a general increase in number average molecular weight (Mn). Organophilic polyorganosiloxanes with Mn > 6000 can be obtained by heat treatment under vacuum or a stream of nitrogen. The thermal stability of the polymer derived from pseudowollastonite in closed systems in the presence of acid/base catalysts is also reported. This work is part of a general programme to prepare higher molecular weight Q/M polymers with more potential uses as industrial materials than the initially prepared trimethylsilylated derivatives.