||January 1, 2008
Silicone heat cured elastomers (HCE) have traditionally been used in the fabrication of rubber components exposed to a wide temperature range for both static and dynamic applications. For performance in chemically harsh environments, trifluoropropyl silicone polymer is used to impart added fuel, oil, and solvent resistance for applications such as automotive and military o-rings, membranes, seals, and gaskets. These specialty products are available commercially and are referred to as Fluorosilicone HCE’s (FVMQ). Over the last several years, the trend in the marketplace for molded silicone rubber parts has been toward the use of liquid silicone injection rubber (LSR) due to its ease of processability, design versatility, excellent quality, and productivity gains. Fluoromethyl co-polymer LSR’s were introduced which offered intermediate fuel and solvent resistance; however, in very harsh environments, FVMQ HCE has still been the material of choice due to its higher fluorine content. Momentive Performance Materials is now introducing a fluorinated liquid silicone rubber (LSR) with comparable fluorine content to fluorosilicone HCE. This paper will compare this new fluorosilicone LSR with fluorosilicone HCE in the areas of processability, physical properties, and fuel and solvent resistance with emphasis on requirements for automotive and military applications.