Rubbers fluorocarbon elastomers

Kader M.A., Bhowmick A.K., Inoue T., and Chiba T. Morphology, mechanical and thermal behavior of acrylate rubber/fluorocarbon elastomer/poly aery late blends, J. Mat Sci., 37, 6789, 2002. 

The most widely used elastomers are natural rubber [17], synthetic polyisoprene and butadiene rubbers, styrene-butadiene copolymers, ethylene-propylene rubber (specifically EPDM), butyl and halobutyl elastomers, polyurethanes, polysiloxanes, polychloroprenes, nitrile rubber, polyacrylic rubbers, fluorocarbon elastomers, and thermoplastic elastomers [18-20]. The examples which have unsaturation present in the repeat units (such as, the diene elastomers) have the advantage of easy cross-linkability, but the disadvantage of increased vulnerability to attack by reactants, such as oxygen and ozone. 

Silastic Rubber, fluoroelastomer, hydrocarbon rubbers and copolyurethane materials have been fabricated into vascular prostheses (27-35). The results with latex rubber. Silastic Rubber, fluorocarbon elastomer, and hydrocarbon rubber were not good. Failure in most instances occurred within 24 hours of implantation in dogs. However, these surfaces are relatively thrombogenic. In addition, these grafts were much less compliant than the natural artery. 

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

Terpolymers in which the acrylate monomer is the major component are useful as ethylene-acrylate elastomers (trade name Vamac) [Hagman and Crary, 1985]. A small amount of an alkenoic acid is present to introduce sites (C=C) for subsequent crosslinking via reaction with primary diamines (Sec. 9-2d). These elastomers have excellent oil resistance and stability over a wide temperature range (—50 to 200°C). They are superior to nitrile and chloroprene rubbers. Although not superior to silicone and fluorocarbon elastomers, they are less costly uses include automotive (hydraulic system seals, hoses) and wire and cable insulation. 

Natural Rubber and Synthetic Polyisoprene Polybutadiene and Its Copolymers Polyisobutylene and Its Copolymers Ethylene-Propylene Copolymers and Terpolymers Polychloroprene Silicone Elastomers Fluorocarbon Elastomers Fluorosilicone Elastomers Electron Beam Processing of Liquid Systems Grafting and Other Polymer Modifications... 

Elastomers, synthetic -acrylic elastomers [ELASTOMERS, SYNTHETIC - ACRYLIC ELASTOMERS] (Vol 8) -butyl rubber [ELASTOMERS, SYNTHETIC - BUTYL RUBBER] (Vol 8) -chlorosulfonated polyethylene [ELASTOMERS, SYNTHETIC - CHLOROSULFONATED POLYETHYLENE] (Vol 8) -ethylene-acrylic elastomers [ELASTOMERS, SYNTHETIC - ETHYLENE-ACRYLIC ELASTOMERS] (Vol 8) -ethylene-propylene-diene rubber [ELASTOMERS,SYNTHETTC - ETHYLENE-PROPYLENE-DIENE RUBBER] (Vol 8) -fluorocarbon elastomers [ELASTOMERS, SYNTHETIC - FLUOROCARBON ELASTOMERS] (Vol 8) -nitrile rubber [ELASTOMERS, SYNTHETIC - NITRILE RUBBER] (Vol 8) -phosphazenes [ELASTOMERS, SYNTHETIC - PHOSPHAZENES] (Vol 8) -polybutadiene [ELASTOMERS, SYNTHETIC - POLYBUTADIENE] (Vol 8) -polychloroprene [ELASTOMERS, SYNTHETIC - POLYCHLOROPRENE] (Vol 8) -polyethers (ELASTOMERS, SYNTHETIC - POLYETHERS] (Vol 8) -polyisoprene [ELASTOMERSSYNTHETTC - POLYISOPRENE] (Vol 9) -survey [ELASTOMERS, SYNTHETIC - SURVEY] (Vol 8)... 

Compounds from solid fluorocarbon elastomers are mixed on the equipment common in the rubber industry. However, the mixing procedures typical for standard types of elastomers are often modified to be suitable for mixing fluorocarbon elastomers. 

Extrusion of tubes, hose, and profiles is done on standard extruders for rubber. The usual temperature pattern is a gradual increase of temperature from the feed zone to the die. The die temperature is typically 100°C (212°F) and the screw temperature is approximately the same as the temperature of the feed zone.37 Processing aids are almost always required to improve the surface appearance and to increase the extrusion rate. Extrusion represents only a small proportion (about 10%) of the total consumption of fluorocarbon elastomers.37... 

Rubber-covered rolls (100% fluorocarbon elastomer or laminated to other elastomers)... 

FIGURE 9.17 Dependence of productivity and separation factor /3p C6H5CH3/H2O of membranes based on various rubbery polymers on the glass transition temperature of the polymer (pervaporation separation of saturated toluene/water mixture, T = 308 K) (1) polydimethyl siloxane (2) polybutadiene (3) polyoctylmethyl siloxane (4) nitrile butadiene rubber with 18% mol of nitrile groups (5) the same, 28% mol of nitrile groups (6) the same, 38% mol of nitrile groups (7) ethylene/propylene copolymer (8) polyepichlorohydrin (9) polychloroprene (10) pol3furethane (11) polyacrylate rubber (12) fluorocarbon elastomer. (From analysis of data presented in Semenova, S.I., J. Membr. Sci., 231, 189, 2004. With permission.)... 

Carboxy nitroso rubber (CNR) n. A fluorocarbon elastomer, synthesized as a... 

Fluorocarbon elastomer (fluoroelastomer) n. Any fluorocarbon polymer of low Tg and no crystalhnity, therefore rubbery. As rubbers, these materials are resistant to high temperature and most chemicals and solvents. Most of the commercial materials are copolymers. In USA, DuPont s Viton materials are most familiar. 

Compounding. Compared with the large number of ingredients required in a conventional rubber recipe, fluorocarbon elastomer compounding seems simple (Table 4) (see Rubber Compounding). 

Mixing. Fluorocarbon elastomers may be compoimded by any standard rubber technique. Open mills may be used, since most commercial gums mix well, except very low viscosity gums, which stick to the rolls, and high viscosity gums, which are very tough. 

Injection molding is increasingly used in the rubber industry and fluorocarbon elastomers are well suited for this technique. Viscosity and cure rheology are very important because of high shear and fast cures (50-54). Molding at 180-200°C allows operations of 5 min or less, depending on part size. 

Cross-linking can be done by various techniques depending on the chemical composition of the polymer. Thus, if the polymer contains C=C unsaturation, e.g. in polydienes, natural rubber, polyisobutylenes (from copolymerized isoprene), then reaction with sulphur forms —S—S— links. With polysiloxanes or EP rubbers (no C=C) then peroxides are used. With fluorocarbon elastomers, e.g. Viton (a copolymer of vinylidene difluoride and hexafluoropropylene), diamines are used which form H-bonded cross-links. With polyurethanes (formed from diols and di-isocyanates) a controlled number (low) of cross-links are formed during the polymerization by the addition of triols. 

Fluoroelastomer Fluoropolymer elastomer Fluorocarbon elastomer Fluorine rubber... 

Diaphragm Valves These valves are limited to pressures of proximately 50 Ibf/in (Fig. 10-154). The fabric-reinforced diaphragms may be made from natural rubber, from a synthetic rubber, or from natural or synthetic rubbers faced with Teflon fluorocarbon resin. The simple shape of the body makes lining it economical. Elastomers have shorter lives as diaphragms than as linings because of... 

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