Cables Cross-linking

Tih-Tay Dual chambers, polyethylene from cables (cross-linked EVA) 1998... 

Improved heat resistance is the most important advantage of cross-linked polyethylene (XITK) over thermoplastic polyethylene. A power cable... 

Advantages of the electron beam processor are its abiUty to penetrate thick and highly pigmented coatings. It is used to cross-link reactive unsaturated polymers, nonreactive thermoplastic polymers, iasulation, and wire-cable covetings (4,9,16) (see Insulation, electric-wire and cable COVERDIGS). 

Cross linked po)y elhylene insulated PVC sheathed cables Power cables w ith extruded cross-linked insulation (XLPE cables) for voltages from 1 kV-3 kV(V = 3.6 kV) 7098-1/1988 ... 

NEMA WC7/1991 (ICEA 5-66-524) Cross linked polyethylene insulated wire and cable for the transmission and distribution of electrical energy ... 

Vulcanised (cross-linked) polyethylene is being used for cable application where service temperatures up to 90°C are encountered. Typical cross-linking agents for this purpose are peroxides such as dicumyl peroxide. The use of such agents is significantly cheaper than irradiation processes for the cross-linking of the polymer. An alternative process involves the use of vinyl silanes (see Section 10.9). 

The excellent electrical insulation properties of polyethylene have led to extensive use in cable and other wire-covering applications. Spectacular early uses included undersea cables and airborne radar and the materials continue to be used in substantial quantities. One particular trend is the increasing use of cross-linked polyethylene for this area of use. Such materials have improved heat resistance and in addition have given generally better resistance to stress cracking. Cellular polyethylene is used as the insulator for television downlead aerials. 

Interest in EVA as a cable-insulating material has arisen because of the good resistance to stress cracking and because the polymer may be more easily cross-linked (see Table 11.12). 

The radiation-treated cables find wide applications in control instmmentation of nuclear power reactors, particle accelerators, aviation, and telephone equipments. Usually PE and PVC are radiation cross-linked for production of such cables. The heat shrinkable foils are widely used in packaging, electrical and electronic industries. The radiation cross-linked PE possesses the property of elastic memory which is utilized to produce heat shrinkable products. 

Cross-linking of wire and cables, heat shrinkable polymeric tubes and films, and PE foam. 

The cross-linked polyethylene retains shape upto 140°C and is used for cable insulation. Polyethylene is the most widely used plastic due to its low cost and ease of processing. 

In the energy domain, new and efficient uses in gas lines, electric cable ducts and the like, will promote surface stabilization and endurance as well as complex stress capability of various extruded or cast systems. Such reactants as acetylene terminated polymers have yielded cross-linked cured, networks of exceptional density and durability. A diimide dianhydride combined with (3) ethynylaniline yields an acetylene terminated tetraimide. On further polymerization at 250°C, the cross-linked structure derived can be used continuously at about 230°C. When this is combined with polymer carbon fibers or filaments, an exceedingly refractory and tough binder is produced. 

There are several interesting applications reported in the literature, such as insulated wire and cable, UV cross-linking of drawn fibers, and tapes from ultra-high-molecular-weight polyethylene. Semi-interpenetrating networks (IPNs) from acrylates and polyurethanes are suitable as UV curable adhesives with high elasticity, good impact resistance, and excellent adhesion to a variety of substrates. ... 

The formation of carbon-carbon cross-links is by far the most important effect and is the basis of the applications in wire and cable industry and for heat-shrinkable products. The factors affecting the changes of polyethylene by irradiation are the molecular weight distribution, branching, degree of unsaturation, and morphology. °... 

More than 30% of the industrial electron beam processors in the world are used in the radiation cross-linking of wire and cable insulation, and this application is growing. 

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

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