Cables Elastomer

Nitrile mbber finds broad application in industry because of its excellent resistance to oil and chemicals, its good flexibility at low temperatures, high abrasion and heat resistance (up to 120°C), and good mechanical properties. Nitrile mbber consists of butadiene—acrylonitrile copolymers with an acrylonitrile content ranging from 15 to 45% (see Elastomers, SYNTHETIC, NITRILE RUBBER). In addition to the traditional applications of nitrile mbber for hoses, gaskets, seals, and oil well equipment, new applications have emerged with the development of nitrile mbber blends with poly(vinyl chloride) (PVC). These blends combine the chemical resistance and low temperature flexibility characteristics of nitrile mbber with the stability and ozone resistance of PVC. This has greatly expanded the use of nitrile mbber in outdoor applications for hoses, belts, and cable jackets, where ozone resistance is necessary. 

Elastomers based on PTMEG have excellent microbial and fungus resistance. Their hydrolytic stabiUty make these elastomers prime candidates for use ia ground-contact appHcations, for example, as jacketing material for buried cables. Because of their good biocompatibiHty, they have also found uses ia medical appHcations, such as catheter tubiag. 

Dow Corning, General Electric, and Shinetsu Chemical Company are the principal suppHers of these elastomers in the United States. It is estimated that the volume used in the United States is between 2700 and 3600 t/yr. The primary uses of these elastomers are in O-rings and shaft seals, as weU as wire and cable, and electrical coimectors. 

The favorable balance of properties of ethylene—acryflc elastomers has gained commercial acceptance for these elastomers in a number of demanding applications, especially in the automotive industry and in wire and cable jacketing. 

Flexible cables for use at mines and quarries Elastomer in.sulafed cables 691/1991, 1026/1991 BS 6708/1998... 

The polymer field is versatile and fast growing, and many new polymers are continually being produced or improved. The basic chemistry principles involved in polymer synthesis have not changed much since the beginning of polymer production. Major changes in the last 70 years have occurred in the catalyst field and in process development. These improvements have a great impact on the economy. In the elastomer field, for example, improvements influenced the automobile industry and also related fields such as mechanical goods and wire and cable insulation. 

Leyden and Rabb [68] have illustrated the rubber formula reconstruction process. Table 2.8 shows some of the difficulties encountered in the reconstruction of a complex wire and cable jacket compound. Forrest [38] has illustrated the reverse engineering of the reasonably complex highly flame retardant elastomer compound of... 

Polyurethane elastomers are exceptionally tough, abrasion resistant, and resist attack by oil. The polyester types (AU) are susceptible to hydrolytic attack at above ambient temperatures, and certain polyester thermoplastic polyurethanes have been known to stress crack in cable jacketing applications when in contact with water at ambient temperatures this latter effect has sometimes, incorrectly, been ascribed to fungal attack. Polyether types (EU) are far more resistant to hydrolytic attack. Certain polyurethanes can be attacked by UV light, the resistance to this agency primarily being determined by the isocyanate used. 

Silicone elastomers find use as gaskets and seals, wire and cable insulation and hot gas and liquid conduits. They also find use in surgical and prosthetic devices. The RTV elastomers are used for sealing and encapsulating. 

The use of silicone elastomers for high-voltage applications (insulators and cable accessories) requires special formulations. Unusually, stringent requirements for these materials must be met.509,510 Fluorosilicone rubbers, which offer some unique combinations of properties (e.g., chemical resistance and higher temperature stability), have attracted considerable attention and have been reviewed in recent publications.511,512 It was noted that a modification of perfluoroether elastomers with silicone elastomer via hydrosilylation reaction opens the possibility of novel applications.5... 

Kevlar fibers are available in four forms Kevlar, Kevlar 29, Kevlar 49 and the recently developed Kevlar 149. Kevlar is designed specifically for reinforcements of elastomers (e.g. tires and belts), while Kevlar 29 is used primarily for tensile members sueh as ropes, cables, webbings and ballistic cloth. Kevlar 49 and 149 are designed for reinforcement of high performance PMCs. Kevlar 149 offers a 40%... 

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. 

Additional curing is often achieved with sulfur, peroxide, or maleimide formulations. Chloro-sulfonated polyethylene has improved resistance to oil, ozone, and heat compared to many other elastomers. Applications include harrier membranes and liners, surface coatings on fabrics, automobile air-conditioner hose, electrical cable insulation, and spark-plug boots [Andrews and Dawson, 1986],... 

Polyolefins and polyvinylctiloride, some elastomers Wire and cable insulation Cross-linking, 0.4—3 MeV, at approx. 10 kGy or higher... 

Cross-linkable polymers used for wire and cable insulations are polyolefins, certain fluoropolymers, and elastomers. Among these, radiation cross-linked polyethylene is the most widely used. The radiation cross-linking process of PE has also been the most widely studied. ... 

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