Silicones, redox metal antioxidants

Incorporation of Redox Metal Antioxidants in Silicone Fluids... 

Certain cerium and iron compounds, when properly incorporated by preoxidation, are excellent antioxidants for dimethyl silicone fluids (DMS) and methylphenylsilicone fluids (MPS). The useful life of these stabilized fluids depends on the temperature, on the concentration and dispersion of the redox metal moieties, and on the conditions of aeration—better aeration providing the longer useful life with inhibited DMS. A mechanism of stabilization by the redox metals has been proposed to account for the observed data. 

It has been observed (a) that aeration plays an important role in prolonging the life of a redox metal stabilized silicone fluid by sweeping away any partially oxidized volatiles to prevent their return to the bulk fluid (b) that aeration is needed to keep some redox antioxidants from... 

The low level of redox metal used for antioxidant protection of silicone fluids requires avoidance of inhibitor loss from solution. Materials used with these fluids must be free of interactions which could excessively remove inhibitor from solution or which could provide a source of easy free radical generation to overwhelm the inhibitor. 

Certain cerium and iron compounds can be useful as antioxidants when properly incorporated into DMS and MPS fluids by preoxidation. The conditions of fluid use determine the level of redox metal required (usually about 0.2 to 3.0 X 10"3 gram atoms/kg.) and the silicone to be used. The role of the redox metal inhibitor is to control the rate of... 

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