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–poly(vinyl alcohol) (PVA) cast films has been investigated. The spectral measurements indicate the responsibility of the Ni2+ ion in its octahedral symmetry. Dopant concentrations higher than 10 wt % Ni Cl2 are found to make the samples more resistant to a degradation effect caused by neutron irradiation. The thermally stimulated depolarization currents (TSDC) of pure PVA revealed the existence of the glass transition Tg and space charge relaxation peaks, whereas doped-PVA samples show a new sub-Tg relaxation peak. A proposed mechanism is introduced to account for the neutron effects on both glass transition and space charge relaxation peaks. The peak positions, peak currents, and stored charges of the sub-Tg relaxation peak are strongly affected by both the concentration of the dopant and neutron exposure doses. © 1993 John Wiley & Sons, Inc.