Radiation effects in thermal properties of polymers. An analytical review. I. Polyethylene

Abstract

The information about radiation effects on the thermal properties of polymeric materials is of special interest since: (1) the temperature regime of technical structural units operated in the radiation fields is determined in many respects by the values of the material thermal constants and the rate of their degradation; (2) the temperature and dose dependencies of heat conductivity and, especially, heat capacity characterize the polymer structure. The data on radiation effects on the thermal conductivity, heat capacity and diffusivity, linear thermal expansion, density, crystallinity degree, heat and temperature of phase transitions are presented in this review only for polyethylene of high and low density, as a very famous and typical semi-crystalline polymer. It is supposed to deal in the future with such problems as reversible radiation effects on heat capacity, analytical models of the radiation-induced changes and anisotropy effects on the thermal conductivity, accumulated radiation energy (“heat defect”) and an important problem of specific action of different kinds of radiation on the thermal properties of polymers.