PROBING OF NANOSTRUCTURE CHANGES IN POLY (VINYL CHLORIDE)/RUBBER BLENDS BY POSITRON LIFETIME AND ELECTRICAL MEASUREMENTS

Abstract

During the last few decades many positron annihilation lifetime spectroscopy (PALS) measurements have been carried out for characterization of the microstructure of various polymeric materials. In the present study the PALS technique was employed for studying the free volume content in the polymer blend system of poly vinyl chloride (PVC)/rubber. Positron annihilation lifetime spectra are usually resolved into three lifetime components. The longest lifetime component τ3 and its intensity I3 were used to determine the free volume parameters. The correlations between PVC content and the mean free volume hole size Vf, and fractional free volume fv were obtained by PALS method. In addition, the electrical measurements such as tracking time and resistivity of the blend system were discussed. Results of PALS measurements shows a slight decrease in the Vf parameter with rubber content in PVC, while the fraction fv showed linear decrease. Characterization of such free volume for nanostructure is important for the development of polymers with improved physical and electrical properties. A distinct correlation was established between the PALS and electrical measurements such as tracking time to be used as a calibration curve for determination of the free volume parameters in a simple way.