Thermal Degradation of Fluorosilicones

Thermal degradation of fluorosilicones can occur by a reversion mechanism and is accelerated by the presence of basic compounds. The maximum long-term service of fluorosilicone elastomers depends on cure conditions and environment and is typically 200°C (392°F) [19]. 

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Reversion and ring formation have been partially overcome through placement of chain-stiffening units in the silicone-backbone. Thus linear D2-m-carborane-siloxanes (11—14) with one to three trifluoropropyl moieties per repeating unit) exhibit better thermal and oxidative stability than silicones and fluorosilicones (J ). Initial degradation occurs in air about 300 to 350 C, almost 100 above that typically experienced for siloxanes and fluorosilicones. The carborane-siloxanes exhibit T s from -50 to 0 C ( 1 ). The carborane moiety also acts to inhibit formation of six-membered rings because of its size. 

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