Thermal, optical and dielectric studies of VO۲+ doped Poly(vinyl chloride)(PVC) films

Pure and VO۲+ doped poly(vinyl chloride) (PVC) films were prepared by using solution casting method. Various techniques including Differential Scanning calorimetry(DSC), Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy(UV-Vis) and Electro paramagnetic resonance(EPR) were employed in the characterization of the samples. The thermal properties of these films were investigated by employing DSC and TGA. Using the DSC thermograms, glass transition temperature (Tg) and melting temperature (Tm) of PVC films were measured. Thermogravimetric curves of pure and VO۲+ doped PVC films showed three distinct steps of weight loss. FTIR results show that the addition of VO۲+ reduces the crystallinity of PVC due to the interaction of vanadium ions with the CH stretching modes of the CH۲ groups. Optical absorption edge and indirect band gap showed a decreasing trend with increasing VO۲+ concentration. From the EPR spectra, the Spin – Hamiltonian parameters (g and A) were evaluated. For dielectric studies films were studied in the frequency range from ۱۰ KHz to ۲ MHz at room temperature. It is observed that with the increase in frequency, the value of dielectric constant decreases up to۱۰۰ kHz, thereafter it becomes almost constant for all the samples.

Keywords:

Poly(Vinyl Chloride) , DSC , TGA , Optical analysis , EPR