Cables and wires

LDPE homopolymers include everything from power cables, insulation for coaxial cables, and telephone cable cores to sheathing material. Especially, for medium- and high-voltage cable insulation, a contamination-free resin with a very low gel level and excellent dielectric properties is required. 

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PVC use [VINYL POLYTffiRS - VINYL Cm ORIDE POLYTffiRS] (Vol 24) -tantalumpowdersfor [TANTALUM AND TANTALUM COMPOUNDS] (Vol23) Wire and cable coverings... 

Polyamides. In 1988, 77% of U.S. demand for adipic acid was for nylon-6,6 fiber, while 11% was used in nyon-6,6 resins (195). In Western Europe only about 66% was for polyamide, because of the stronger competition from nylon-6. The fiber appHcations include carpets (67%), apparel (13%), tire cord (7%), and miscellaneous (13%). Nylon-6,6 resins were distributed between injection mol ding (85%) for such appHcations as automotive and electrical parts and for extmsion resins (15%) for strapping, film, and wire and cable. 

Bis(bexacbIorocycIopentadieno)cycIooctane. The di-Diels-Alder adduct of hexachlorocyclopentadiene [77 7 ] and cyclooctadiene (44) is a flame retardant having unusually good thermal stabiUty for a chlotinated aUphatic. In fact, this compound is comparable ia thermal stabiUty to brominated aromatics ia some appHcations. Bis(hexachlorocyclopentadieno)cyclooctane is usedia several polymers, especially polyamides (45) and polyolefins (46) for wire and cable appHcations. Its principal drawback is the relatively high use levels required compared to some brominated flame retardants. 

Aryl Phosphates. Aryl phosphates were introduced into commercial use early in the twentieth century for flammable plastics such as cellulose nitrate and later for cellulose acetate. CeUulosics are a significant area of use but are exceeded now by plastici2ed vinyls (93—95). Principal appHcations are in wire and cable insulation, coimectors, automotive interiors, vinyl moisture barriers, plastic greenhouses (Japan), furniture upholstery, conveyer belts (especially in mining), and vinyl foams. 

D. Paul, "A New Phosphate Plasticizer for Low Smoke Wire and Cable AppHcations," paper presented at 3rd Annual BCC Conference on Recent advances in Flame Retardany of Polymeric Materials, Stamford, Conn., May 19—21,1992. 

Safe Handling Guide, Teflon Fluorocarbon Resins, du Pont Materials for Wire and Cable, bulletin E-85433, E. I. du Pont de Nemours Co., Inc., Wilmington, Del., 1986. 

M. I. Bro and co-workers, 29th International Wire and Cable Symposium, Cherry Hill, N.J., Nov. 1980. 

After 10 years of unabated rapid growth in the plenum wire and cable market, fluoropolymers including PVDE, primarily the flexible VDE/HEP copolymer, are beginning to lose market share to lower priced PVC-akoys. The loss of market share in the plenum market probably wkl be compensated by growth of PVDE in other fields thus during the mid-1990s the total volume of PVDE may not grow (188). 

Phosphazene polymers are inherently good electrical insulators unless side-group stmctures allow ionic conduction in the presence of salts. This insulating property forms the basis for appHcations as wire and cable jackets and coatings. Polyphosphazenes also exhibit excellent visible and uv radiation transparency when chromophoric substituents are absent. 

The aryloxyphosphazene polymers, on the other hand, have been used primarily ia wire and cable coatings and jackets and as fire-resistant, low smoke, closed-ceU foams and sound-barrier sheets. 

The U.S. Department of Commerce Bureau of Census reports that in 1990 the total value of iasulated wire and cable shipments was more than 10.5 biUion. These shipments have grown more than 165% compared to 1983 and more than 225% compared to 1977. 

Each segment of the insulated wire and cable industry has its own set of standards, and cables are built to conform to specifications provided by a large variety of technical associations such as The Institute of Electrical Electronic Engineers (IEEE), The Insulated Cable Engineers Association, (ICEA), National Electrical Manufacturers Association (NEMA), Underwriters Laboratories (UL), Rural Electrification Administration of the U.S. Department of Agriculture (REA), Association of Edison Illumination Companies (AEIC), MiUtary Specifications of the Department of Defense (MIL), American Society for Testing and Materials (ASTM), National Electrical Code (NEC), etc. 

Each segment of the insulated wire and cable industry has its own set of standards, some of which are quite compHcated because of requirements imposed by specific appHcations and/or environments. The most complex specifications are typically imposed on power cables and telecommunication wires. 

Table 2. Wire and Cable Insulation PVC Formulations, Parts by Weight...

Union Carbide Corp., Kabelitems Wire and Cables No. 150, 152, Treeing Update, Danbury, Conn. 

B. F. Goodrich Co., Typical Properties of Geon Uinyl Compounds for Wire and Cables Insulation and Jacketing, bulletin, Cleveland, Ohio, 1991. 

Electrical Properties. Erom a chemical standpoint, HDPE is a saturated aUphatic hydrocarbon and hence a good insulator. Its electrical characteristics are given in Table 1. Because polymer density and molecular weight affect electrical properties only slightly, HDPE is widely used for wire and cable insulation. 

Because it is a saturated aUphatic hydrocarbon, LLDPE does not conduct electricity, and so is widely used for wire and cable insulation. LLDPE is poorly permeable to water and inorganic gases and only slightly more so to organic compounds, whether Hquid or gas. 

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