OPTICAL-ABSORPTION AND THERMALLY STIMULATED DEPOLARIZATION CURRENT STUDIES OF NICKEL CHLORIDE-DOPED POLY(VINYL ALCOHOL) IRRADIATED WITH LOW-LEVEL FAST-NEUTRON DOSES

The influence of neutron irradiation on ultraviolet/visible absorption and thermally stimulated depolarization current in nickel chloride-po ly(vinyl alcohol) (PVA) cast films has been investigated. The spectral measurements indicate the responsibility of the Ni2+ ion in its octah edral symmetry. Dopant concentrations higher than 10 wt % Ni Cl-2 are found to make the samples more resistant to a degradation effect cause d by neutron irradiation. The thermally stimulated depolarization curr ents (TSDC) of pure PVA revealed the existence of the glass transition T-g and space charge relaxation peaks, whereas doped-PVA samples show a new sub-T-g relaxation peak. A proposed mechanism is introduced to account for the neutron effects on both glass transition and space cha rge relaxation peaks. The peak positions, peak currents, and stored ch arges of the sub-T-g relaxation peak are strongly affected by both the concentration of the dopant and neutron exposure doses. (C) 1993 John Wiley & Sons, Inc.