Correlation of electrical and swelling properties with Nano free volume structure of conductive silicone rubber composites

Abstract EN

The present study focuses on finding a correlation between the positron annihilation parameters in silicone rubber based on Poly dimethyl siloxane (PDMS) composites loaded with different conductive fillers and their swelling and electrical properties.

Four types of conductive fillers have been used in this study: carbon black, graphite, copper, and nickel powders.

The maximum degree of swelling Qm %, the penetration rate, P, as well as the diffusion coefficient, D, decrease with increasing the filler content due to the reduction of the size of free volume, as observed through a decrease of the probability of ortho-positronium (o-Ps) formation I3 and the o-Ps lifetime τ3, representing the size of free volume measured by the positron annihilation lifetime technique (PAL).

The electrical conductivity ln (σ) is positively correlated with the probability of free annihilation of positrons at interfaces I2, thus suggesting an increase in the electron density with the filler content.

The activation energy of conduction, Ea, is found to decrease with the increase in the loading of conductive filler and the particle size of the filler.

A correlation between the free-volume Vf, and the d.c.

electrical conductivity ln (σ) is found to be in accordance with Miyamoto and Shibayma model of ion conduction.