Kinetics of solidification of cross-linked polyethylene

In the production of extruded dielectric cables the molten polymer is invariably quenched following extrusion. During this process crystallization of the polymer occurs at a series of different temperatures depending on the thermal conductivity of the polymer in question. For cross-linked polyethylene the polymer is chemically cross-linked immediately after extrusion and prior to quenching. Separation of impurity molecules and of low molecular weight polyethylene molecules generally occur during the crystallization process. The rate at which such separation processes occur may have an influence on electric breakdown behavior. When in use the temperature of the cable may exceed the melting point resulting in re-crystallization under totally different thermal conditions from those under which crystallization occurred during manufacture. A different morphological structure may result under such circumstances. In this paper we wish to report studies of the crystallization behavior of chemically cross-linked polyethylene and to discuss the ways in which it differs from the uncross-linked polymer.