Semi-Conducting Composites Containing a Ladder Polymer as a Conductive Filler

Abstract

This study is concerned with the use of a novel ladder polymer (SCL) as a conductive filler in insulating thermoplastics and thermosets. SCL, which had apristine electrical conductivity of 8.0 x 10^-6 Scm^-1, was mixed with poly(methylmethacrylate) (PMMA) and polyesters in various volume loadings in order to determine percolation behaviour. A maximum electrical conductivity of 1.2 x 10^-8 Scm^-1 was observed at loading of 13% v/v in polyester resin, while the maximum conductivity observed with PMMA was 7.3 x 10^-7 Scm^-1 at a loading of 11.2% by volume. The maximum conductivity was slightly lower for thin composite films of SCL/ PMMA. The thermal stability of the composite samples was found to be dependent upon the thermal stability of the host plastic since the composite showed decomposition behaviour characteristic of two separate phases. Thermal ageing of the composite samples at 100°C and 175°C showed that the electrical conductivities were stable at these temperatures over long periods of time. However, ageing at 250°C led to a decrease in electrical conductivity.