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Own Irradiation Center for X-Ray of XLPE and PVC Wires.
Improvement of Flame-Retardant properties of insulated wires by radiation crosslinking Electric wires coated with XLPE and PVC.
Electric wires coated with polyethylene insulation crosslinked by a chemical method (gel fraction = 80%) and a jacket of self-extinguishing resin were produced. The jacket was crosslinked by irradiation with rays or accelerated electrons. Flame retardant properties of the wire improved by -ray induced crosslinking up to 60% gel fraction in the jacket. Beyond this point, however, the flame resistance rapidly decreased with increasing gel fraction. The flame resistance was also improved by irradiation with electrons, but the extent of the improvement was strongly dependent on the energy of incident electrons. This fact was attributed to the difference in the distribution of energy dissipation, i.e., crosslinks formed in the jacket. By introducing a double layer structure to the jacket, in which the inner layer adjacent to the polyethylene insulation was crosslinked more densely than the outer layer, the wires were markedly improved in resistance to flame and heat deformation.
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