Abstract: When a small amount of polytetrafluoroethylene powder is mixed with certain curable polydiorganosiloxane compositions containing a reinforcing silica and an organic peroxide curing agent and the resulting mixture is extruded and heat-cured, the resulting elastomeric article has a durometer of less than 30 and has a greatly reduced amount of porosity or bubbles.

Abstract: Phosphorus-containing catalysts that are suitable for polymerizing polyorganosiloxanes are prepared from tetraorgano phosphonium halides, a basic compound, such as sodium hydroxide, and an organosilicon compound. The catalyst must be prepared at a temperature of at least 30.degree. C. The catalysts are moisture sensitive but possess improved shelf-life stability. They are used to polymerize polyorganosiloxanes and can subsequently be inactivated by heating to a temperature above approximately 130.degree. C. for a suitable length of time.

Abstract: An aromatic acid is mixed with a flame-retardant silicone elastomer composition to further increase the flame retardancy of the composition. For example, a flame-retardant silicone composition comprising a polydiorganosiloxane gum, a reinforcing silica filler, a platinum-containing material, a flame-retardant additive such as titanium dioxide, an alcohol-producing organic peroxide such as 2,5-bis(tertiary butyl peroxy)-2,5-dimethylhexane and an aromatic acid such as 2,4-dichlorobenzoic acid has better flame retardancy in the cured state than does a similar composition having no aromatic acid added.

Abstract: A light-fugitive dye is added to silicon-containing priming compositions to aid in the application of the priming compositions to a surface and to aid in the application of silicon-containing coating compositions over the primed surface before becoming colorless in the presence of light.