Cable and Wires Insulation

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. 

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

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. 

PVC—nitrile mbber permanent plasticization of PVC, improved processibihty wire and cable insulation, food contact service 141,317,318... 

Electrical Applications. Plastics are used for electrical insulation, conduit and enclosures, lighting fixtures, and mechanical devices. The most widely used plastic for wire and cable insulation is flexible, plasticized PVC, which constitutes well over half the market in insulating wires for buildings, automobiles, appHances, and power and control lines. Polyethylene is also a factor. Higher performance plastics such as nylon and fluoropolymers also play a smaller role in this area. 

Wire and cable insulation based on vulcanizates of PZ has also been studied. Again, low fire risk was the target property, and this was achieved. The need to vulcanize the coating, somewhat modest tensile properties, tensile strength of 5.2 to 12.2 MPa (760 to 1770 psi), and high dielectric constant (4—5 at 10,000 Hz) limited interest in this appHcation (19). 

The market for PPVC film and sheet is only slightly less than for wire and cable insulation. Uses are as diverse as seepage barriers, factory doors, inflatables, baby pants, car trim, covering materials for book bindings and document cases and shower curtains. UPVC film has also been widely used for packaging of food, particularly for shrink-wrap purposes, but this market has been subject to some substitution by polypropylene. 

This copolymer has proved particularly suitable for wire and cable insulation, with many grades being rated at 155°C for 20 000 h continuous exposure. It is extensively used in electrical systems for aircraft, underground railways, computers, telecommunications installations and heating circuits. Because of its toughness combined with its heat and chemical resistance it also finds use for lining pumps and valves and other equipment for the chemical industry and for laboratory ware. 

These materials are developed from the polyetherimides introduced by General Electric (see also Section 18.14.2). At the time of writing one grade, Ultem Siltem STM 1500, is being offered. It is of particular interest as a material for wire and cable insulation, as it not only has excellent flame resistance coupled with low smoke generation but also avoids possible toxic and corrosion hazards of halogenated polymers. This can be of importance where there are possible escape problems in the event of a fire, such as in tunnels, aircraft and marine (particularly submarine) vessels. 

P Injection, blow, extrusion and rotational Pipe, pipe fittings, surgical implants, coatings, wire and cable insulation... 

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. 

Flexible PVC grades account for approximately 50% of PVC production. They go into such items as tablecloths, shower curtains, furniture, automobile upholstery, and wire and cable insulation. 

Butyl ruhher vulcanizates have tensile strengths up to 2,000 psi, and are characterized hy low permeahility to air and a high resistance to many chemicals and to oxidation. These properties make it a suitable rubber for the production of tire inner tubes and inner liners of tubeless tires. The major use of butyl rubber is for inner tubes. Other uses include wire and cable insulation, steam hoses, mechanical goods, and adhesives. Chlorinated butyl is a low molecular weight polymer used as an adhesive and a sealant. 

Flexible RP These materials are used with elastomeric materials providing special engineered products such as conveyor belts, mechanical belts, high temperature or chemical resistant suits, wire and cable insulation, and architectural designed shapes. 

Table II. Properties of Poly(aryloxyphosphazene) Wire and Cable Insulation/Jacketing...

Polymers are widely used as electrical insulators in applications such as wire and cable insulation, electrical appliance housings and capacitor films. Polymers used in these applications include polyvinyl chloride, polyethylene, and isotactic polypropylene. 

Peterson, T. C. "Polyphosphazene Wire and Cable Insulation", Horizons Research, Inc., Cleveland, Ohio, Dec 1979, DTNSRDC Contract N00024-78-C-4644, ADA091410. 

Low density polyethylene is used in making film and sheeting, injection moulding, wire and cable insulator, coating and blow moulding. 

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. 

Wire and cable insulation consumes 4% of all PVC with construction and automotive wires, electrical cord jacketing, fibre optic sheathing, heat-shrinkable sleeves. .. Components in phone systems, power tools, refrigerators, washing machines, air conditioners, computers, keyboards, housings. .. 

Electrical sleeving, wire and cable insulation and jacketing, appliance wires, motor lead wires, compact wire and cables, airframe wiring, extruded coatings... 

Combustion products can affect sensitive electronic equipment. For example, hydrogen chloride (HCI) is formed by the combustion of PVC cables. Corrosion due to combusted PVC cable can be a substantial problem. This may result in increased contact resistance of electronic components. Condensed acids may result in the formation of electrolytic cells on surfaces. Certain wire and cable insulation, particularly silicone rubber, can be degraded on exposure to HCI. A methodology for classifying contamination levels and ease of restoration is presented in the SFPE Handbook... 

LLDPE—telephone jacketing, wire and cable insulation, piping and tubing, drum liners, bottles, films... 

The second type of EPM is the EPDM, which is made by polymerizing ethylene, propylene, and a small amount (3-10 mol%) of nonconjugated diolefine employing ZNCs. The side chains allow vulcanization with sulfur. They are employed in the production of appliance parts, wire and cable insulation, coated fabrics, gaskets, hoses, seals, and high-impact PP. 

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