Fluorocarbon rubbers

Interesting TPEs can be derived from binary and ternary blends of polyfunctional acrylates, ACM, and fluorocarbon rubber (FKM) [53]. During the blend preparation, the liquid multifunctional acrylate monomer used is polymerized and forms the continuous matrix encapsulating the... 

Mechanical Properties of Thermoplastic Elastomers Based on Acrylate Rubber-Fluorocarbon Rubber-Polyacrylate Monomer... 

FIGURE 31.13 (a) Plot showing the stress-strain behavior of various irradiated rubbers, (b) Plot showing the variation of tensile strength and modulus of rubbers irradiated with different doses, (c) Plot showing the variation of hysteresis loss, set, and elongation at break of irradiated fluorocarbon rubbers. (From Banik, I. and Bhowmick, A.K., Radial. Phys. Chem., 54, 135, 1999. With permission.)... 

Thermal degradation studies of EB-cured terpolymeric fluorocarbon rubber [430] by nonisothermal thermogravimetry in the absence and presence of cross-link promoter TMPTA reveal that thermal stability is improved on radiation and more so in the presence of TMPTA. Initial decomposition temperature, maximum decomposition temperature and the decomposition... 

Some examples of fluorocarbon rubbers are listed here. 

High resistance to almost all inorganic chemicals, ammonia being the most important exception. Resistance to most organic compounds, except low molecular weight polar organics. Least resistant of the fluorocarbon rubbers to methanol and phosphate ester based hydraulic fluids. 

Acrylic rubber Chlorinated polyethylene Chlorosulphonated polyethylene Ethylene-propylene copolymer Ethylene-propylene terpolymer Fluorocarbon rubbers (certain grades)... 

Other Accelerators. Amine isophthalate and thiazolidine thione, which are used as alternatives to thioureas for cross-linking polychloroprene (Neoprene) and other chlorine-containing polymers, are also used as accelerators. A few free amines are used as accelerators of sulfur vulcanization these have high molecular weight to minimize volatility and workplace exposure. Several amines and amine salts are used to speed up the dimercapto thiadiazole cure of chlorinated polyethylene and polyacrylates. Phosphonium salts are used as accelerators for the bisphenol cure of fluorocarbon rubbers. 

Fig. 18 Variation of a tan 8 versus temperature, and b log E versus temperature for different fluorocarbon rubber nanocomposites (V refers to vulcanized samples)...

There are a number of grades of fluorocarbon rubber (copolymers, terpolymers and tetrapolymers) and they are mainly used in applications where the temperatures would degrade ethylene-propylene rubber products. They are able to withstand prolonged use at temperatures up to 200 °C. Typical conditions are high temperature (<150 °C) gaskets under flow or static conditions, in contact with aqueous or fatty foods (including oils). 

There is a relatively large range of different types of rubbers that are used in different components in the food industry that can get in contact with the food. The most important of these are natural rubber (NR ds-l,4-polyisoprene), nitrile rubber (i.e., acrylonitrile-butadiene copolymer), ethylene-propylene rubber (EPR), rubbers of ethylene-propylene monomer (EPM) and EPDM, SBR, fluorocarbon rubber, silicone rubber, polybutadiene rubber (BR), polychloroprene rubber, and TPE. In addition, there is the use of rubber blends, i.e., blends of NR and N Rr with SBR [19]. 

Fluorocarbon rubbers are used in seals and gaskets, specifically for use at high temperatures for prolonged use, especially in contact with fatty (oily) foods. 

The foremost elastomers for maximum high temperature resistance are the fluorocarbon rubbers. They play the same role in the rubber field as poly-tetrafluoroethylene ("Teflon") does in plastics. Furthermore, the inert fluorine atoms also impart a high solvent resistance as well. Hence it is not surprising that these elastomers are in a "class by themselves" (also as regards costl )... 

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