Polymer00013 - vinylidene fluorine (VDF)/hexafluoropropylene

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2 There are two general types of rubbers or elastomers, i.e., crosslinked elastomer and thermoplastic elastomer (TPE). Most of the commonly used rubbers are crosslinked ones with their chains chemically bonded during the curing process. Once formed, this type of rubber cannot be reprocessed, softened, melted or reshaped by following reheating. Thermoplastic elastomers, on the other hand, are rubbers which act in a way similar to crosslinked materials but are copolymers or physical mix of thermoplastics and rubbers with both thermoplastic and elastomeric properties. These elastomers are usually hydrocarbon-based polymers mainly consisting of carbon and hydrogen atoms. Fluoroelastomers, as a special kind of elastomers, are widely used in many industrial applications due to their excellent heat, oil and solvent resistances (Kader and Nah 2004). Regarding the structure of monomer, main families of fluoroelastomers include dipolymer of vinylidene fluorine (VDF)/ hexafluoropropylene (HFP), terpolymer of
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Unformatted text preview: vinylidene fluorine (VDF)/hexafluoropropylene (HFP)/tetrafluoroethylene (TFE), and peroxide-vulcanizable polymers which are similar to terpolymers (Jagels, 2005). Fluoroelastomers meet rigorous performance requirements in harsh environments, enhancing reliability, safety, and environmental friendliness. Fluoroelastomers are growing as products of choice for critical components such as O-rings, hoses, and seals in hostile fluid and temperature conditions. These elastomers are mostly compounded with inorganic fillers such as carbon black, silica, clay, etc. to enhance the mechanical properties, to change the electrical conductivity, to improve the barrier properties or to increase the resistance to fire and ignition. However, a minimum of 20 wt% of the filler content is always required for a critical property enhancement, which may lead to many problems in processing and curing, such as reducing the processability of the elastomer...
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