Effect of Crosslinking and Doping on Thermoluminescence of U.V.‐Irradiated Polymers

The thermoluminescence (TL) of elastomeric materials modified by doping and chemical or γ‐induced crosslinking was measured following irradiation with u.v. light at 77 K and compared with the thermally stimulated depolarization currents (TSDC) obtained during warmup of samples previously polarized from 298 to 77 K, stressing the comparison of luminescence and current peaks observed in the glass transition range. Significant shiftings of the TL peaks were found as a function of degree of crosslinking and nature of the dopant, even though the glass transition temperature and the position of the TSDC peaks were not affected, showing that the kinetics of the light‐emitting process is not only governed by the thermal motions of the polymer units but also critically depends on the nature of traps and luminescent species. Generally speaking, the TL method appears to be much more sensitive than the classical relaxation methods to any structural, morphological, or environmental change of the macromolecular chains and seems, thus, particularly attractive to obtain valuable information on new aspects of polymer relaxation.