Dielectric relaxation in a cadmium chloride-doped polymeric blend

[摘要] The temperature-and frequency-dependent relaxation processes in films of a polymeric blend comprising a polyvinyl alcohol (PVA)/polyvinyl acetate (PVAc) co-polymer blendedwith polyvinyl pyrrolidone (PVP) in equal proportion by weight, and doped with an inorganic metallic salt, cadmium chloride (CdCl$_2$), at 0.0 wt% and 10.2 wt% doping levels (DLs), have been studied using dielectric relaxation spectroscopy (DRS). The frequency response of dielectric parametersfor these samples has been studied with variation in temperature, from 303 up to 373 K, at different fixed frequencies (from 12 Hz up to 200 kHz). Study of Cole–Cole plots reveals a decrease in bulk resistivity of the samples with increase intemperature, which is attributed to thermally induced increase in the mobility of polymer chains. A 10-fold increase in bulk conductivity is observed for doped films with a DL of 10.2 wt%, when compared with the bulk conductivity of the un-doped (0.0 wt% DL) sample. The temperature dependence of dielectric parameters at different frequencies has been studied and the activation energy has been calculated. The relaxation time is found to be of the order of a few milliseconds, which implies that electrical conduction in CdCl$_2$-doped PVA/PVAc–PVP blend films is predominantly due to the migration of ions. Thevariation of AC conductivity with frequency is in agreement with Jonscher’s universal power law. AC conductivity of the sample is found to increase significantly with an increase in temperature of the sample. Frequency-dependent dielectric properties of CdCl$_2$-doped PVA/PVAc–PVP blend films, for various DLs, are also studied at room temperature.

[学科分类] 材料工程

[关键词] Cole–Cole plot;CdCl$_2$-doped PVA/PVAc–PVP;dielectric loss;dielectric relaxation spectroscopy;electric modulus.