Thermally Stimulated Relaxation and Electrical Conduction Phenomena in Polyacrylamide

Thermally stimulated relaxation (TSR), employing thermally stimulated luminescence (TSL) and thermally stimulated conductivity (TSC) as experimental techniques, in Polyacrylamide (PAA) have been studied; in the temperature range 300 - 480 K. Measurements of electrical conductivity (σ) at various temperatures, in the same temperature range have been made, in both as-grown and UV-irradiated PAA films; to elucidate the mechanism of charge transport in relation to the macromolecular relaxations in PAA. Two TSL and TSC glow curves with maxima at 375 and 475 K have been observed. The logσ vs 1/T plots showed two transition temperatures with changes in slopes; indicating the on-set of molecular motion in PAA. The TSL/TSC curves at 475 K are attributed to the β-relaxation near the glass transition temperature of the polymer. The β-relaxation is considered to be associated with the glow curve at 375 K. Analysis of TSL / TSC curves and electrical conductivity plots have been made and the results are correlated. The two endothermic peaks recorded by Differential scanning calorimetry (DSC) are correlated with the TSL/TSC α and β - relaxations in Polyacrylamide.