Formation of silicone fluid at the surface of RTV silicone rubber coating due to heat

The formation of low-molecular-weight silicone fluid at the surface of room temperature vulcanizing (RTV) silicone rubber coatings is shown to occur as a direct result of applying heat. Two independent methods are employed to demonstrate this phenomenon. In the first, the specimen surface is subjected to bombardment by varying energy input from a laser beam to generate the heat. In the second experiment the RTV specimens are subjected to varying amounts of heat energy in a thermal oven at 240/spl deg/C by varying the length of time of exposure. In the latter experiment both the bulk and the surface of the coating are subjected to heat. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to investigate the formation of the silicone fluid after the specimen was subjected to heat. The formation of silicon fluid is shown to be more pronounced with higher energy input. The heat that penetrates into the bulk of the RTV coating changes the PDMS (polydimethylsiloxane) molecules and forms short PDMS chains. Therefore, the silicone fluid increases in the bulk of the RTV coating.<>