Wire and cable applications

Retard efficiently oxidation of polymers catalysed by metal impurities. Function by chelation. Effective metal deactivators are complexing agents which have the ability to co-ordinate the vacant orbitals of transition metal ions to their maximum co-ordination number and thus inhibit co-ordination of hydroperoxides to metal ions. Main use of stabilisation against metal-catalysed oxidation is in wire and cable applications where hydrocarbon materials are in contact with metallic compounds, e.g. copper. 

The main applications of butyl rubber are in wire and cable applications, inner tubes, inner liners in tubeless tyres, tyre curing bladders, and pharmaceutical closures, the latter utilising the low... 

Wire and cable applications and extrusion profiles, e.g., window seals and car door seals, probably form the major applications for EPM and EPDM rubber, although they are also used in a wide variety of other extrusion and moulding applications. Washing machine door seals moulded from EPDM are starting to replace NR as washer/dryers are becoming more common. 

The excellent UV stability of chlorosulphonated polyethylene has led to wide use as a roof sheeting material, the ability to compound this material to slowly cure at ambient temperatures being an added advantage another sheeting application is pond liners. Wire and cable applications, coated fabrics, and items made from them, hoses and moulded goods are other areas in which this material finds use. 

The main use of EVA is in wire and cable applications, although the electrical properties are inferior to those of EPDM. EVA is used for some medical extrusions and can be blended with other polymers to improve ozone resistance. 

PVC has been used in wire and cable applications since World War IT. The compounds are optimized for the requirements, including low temperature flexibility, high use temperature, especially low combustibility, weatherability. and high resistance to cutthrough. 

Decabromodiphenyl ether is also used for polyethylene wire and cable applications included at a level of 20-24 wt%. Chlorinated paraffin with a loading of about 25 wt% is also used. 

Hydromagnesite (usually found in combination with huntite) has intermediate thermal stability, decomposing between 220°C and 240°C.21 22 Mixtures of these minerals are used in wire and cable applications, due to their higher thermal resistance than ATH and lower cost compared to MH. They have also been considered for use in ethylene-propylene copolymers23 and poly(vinyl chloride) (PVC) formulations, where reduced smoke and acid gas emission are requirements.24... 

Material Design for Fire Safety in Wire and Cable Applications... 

Selection of polymer type and FR additive technology can have significant impact on meeting flame resistance requirements as specified by the above standards.56 Therefore, material selection and standards are directly interrelated. A summary of key material options for FR wire and cable applications follows. 

The most common polymers used in FR wire and cable applications are PVC, polyolefins, fluoropolymers, and silicone polymers. Thermoplastic polyurethanes (TPUs) and other specialty polymers such as chlorosulfonated polyethylene also serve niche applications in wire and cable. The approaches to achieve flame retardancy in each of these polymer systems along with issues unique to wire and cable application are discussed in the following sections. 

After PVC, polyolefin copolymers, predominantly polyethylene copolymers, are the next most widely used material for FR applications in wire and cable. Polyethylenes have very good dielectric strength, volume resistivity, mechanical strength, low temperature flexibility, and water resistance. In contrast to PVC, polyolefins are not inherently FR and thus are more highly formulated, requiring the addition of FRs to meet market requirements for flame retardancy. For this reason, and because of the steady global trend toward halogen-free materials for wire and cable applications, more space will be devoted to this section on FR polyolefins compared with the above discussion of PVC. 

Natural sources of ATH (Gibbsite extracted from Bauxite) and magnesium hydroxide (Brucite) are available but generally have large particle size as a result of grinding operations and contain significant amounts of impurities. In wire and cable applications, finer particles sizes are utilized for higher FOI values, improved mechanical properties, lower brittleness temperatures, and smoother surface characteristics despite the drawback of increased mixture viscosity.75... 

As discussed earlier, many FR qualification tests for wires and cables, according to applicable standards, require testing on a fully fabricated article. However, to conduct research toward new materials for use in wire and cable applications, it is often desirable to obtain directional information in the early stages by conducting laboratory-scale tests that are capable of discerning improvements in FR characteristics of materials. Later in the product development process, optimization, validation, and qualification must nevertheless be conducted on full-scale articles and equipment. 

Lee, D.C., Laakso, R., Gross, L., Muskopf, J., Olefinic elastomers for wire and cable applications, in Proceedings of the 55th IWCS/Focus International Wire Cable Symposium, Providence, RI, 2006, pp. 158-163. 

Wire and Cable. PVC has been used in wire and cable applications since Wodd War II, when the U.S. Navy demanded lower combustibility materials in construction. These products are manufactured by cross-head extrusion, usually from pellet compounds on single-screw extruders. Some line speeds are 1524 m (5000 ft) per minute (60 mph). The compounds are optimized for the requirements, including low temperature flexibility, high use temperature, especially low combustibility, weatherability, and high resistance to cutthrough. 

Non-lead and heavy-metal-free (HMF) stabilised PVC compounds present a viable material alternative to vinyl lead-based systems for wire and cable applications. Trends driving the use of these non-lead and HMF materials in... 

Risk reduction is a world wide problem and of course a concern to the field of PVC stabilisers. The replacement of lead stabilisers in wire and cable applications is demonstrated. Newly developed non-lead stabilisers (RUP-series) are shown to offer excellent heat stability, electrical and mechanical properties compared with traditional wire and cable formulations. The overall processability is shown with experimental and actual results. The gradual increase in use of ADKs and other non-lead stabilisers in the USA and Japan demonstrates industry s concern for the public demand in saving the environment without direct laws banning the use of lead. JAPAN... 

The compound 3,9-divinyl-2,4,8,10-tetraoxaspiro-[5.5]undecane together with a peroxide is utilized in the cross-linking or curing of polyethylene for wire and cable applications. Addition of 2,4-diphenyl-4-methyl-l-pentene (AMSd) inhibits scorch or premature cross-linking of the polymer, presumably through interception of the radicals.490... 

Use For electrical properties for outdoor wire and cable applications. In vinyls, combines good heat and light stability with high compatiblity. 

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