Cables Thermosets

The search for materials to aid in the defense effort during World War II resulted in a profound impetus for research into new plastics. Polyethylene, now one of the most important plastics in the world, was developed because of the wartime need for better-quality insulating materials for such applications as radar cable. Thermosetting polyester resins (now used for boatbuilding) were developed for military use. The terpolymer acrylonitrile-butadiene-styrene (ABS), (telephone handsets, luggage. 

During World War 11, people worldwide searched for materials for use in defense purposes, which provided substantial impetus for research into new plastics. Polyethylene was developed because superior-quality insulating materials were required during the war period for use in items such as radar cables. Thermosetting polyester resins were originally developed for military applications, but are now used for boat building. 

Properties desired in cable insulation and flexible circuit substrate materials include mechanical flexibiUty, fatigue endurance, and resistance to chemicals, water absorption, and abrasion. Both thermoplasts and thermosets are used as cable-insulating materials. Thermoplastic materials possess excellent electrical characteristics and are available at relatively low cost. 

Specification for 600/1000V and 1900/3300 V armoured electric cables having thermosetting insulation Fire resisting characteristics of electric cables Performance requirements, sample and lest conditions - BS 5467/1997... 

Power Cables. The materials mosdy used to produce power cables are ethylene copolymers loaded with conductive carbon black for semiconductive shielding layers, polyethylene or ethylene—propylene mbber-based compounds as insulations, and either thermoplastic materials (eg, polyethylene, PVC) or thermosetting (based on chlorinated polyethylene (CPE), chlorosulfonated polyethylene (CSPE), chloroprene, etc) for jackets. 

Insulation, Cross-linked polyethylene (XPLE) and ethylene—propylene mbber (EPR), both thermosets, are the primary extruded dielectrics used in medium and high voltage power cables (Table 4). 

HexceL [Hexcel] Thermoset polyurethane compds. encs ulants for cable plugging. 

Micral . [Solem Industries] Alumina trihydrate smoke suppressor/flame retardant fmr wire and cable insulation, inj. ntelded polyolefins, coatings, adhesives, rubber goods, paper filler and coating, PVC, EPDM, EPR, ABS, XLPE, and compr.-molded thermosets. 

The thermoset elastomers most frequently used for cables are ethylene propylene rubber and cross-linked polyethylene. 

Thermosets are widely used as sheet type insulating materials, adhesives, jointing compounds for cables and solid mouldings such as post insulators. 

There are many thermoplastic and thermoset resins but only a few developed for use in manufacturing cables. Table 9.5 summarises the main properties of the more frequently used resins. 

BS5467 Specification for 600/1000 V and 1900/3300 V armoured electric cables having thermosetting insulation. 

BS6724 Armoured cables for electricity supply having thermosetting insulation with low emissions of smoke and corrosive gases when affected by fire. 

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