Evaluation of a.c. conductivity behaviour of graphite filled polysulphide modified epoxy composites

[摘要] Composites of epoxy resin having different amounts of graphite particles have been prepared by solution casting method. Temperature dependence of dielectric constant, tan ð›�? and a.c. conductivity was measured in the frequency range, 1â€�??20 kHz, temperature range, 40â€�??180°C for 0.99, 1.96 and 2.91 wt% graphite filled and unfilled epoxy composites. It was observed that the dielectric constant, tan ð›�? and a.c. conductivity increase with increasing temperature. Near the transition temperature the materials show anomalous behaviour for the observed properties. Peaks of dielectric constant, tan ð›�? and a.c. conductivity were observed to shift towards lower temperature with increasing frequency. Clear relaxation (tan ð›�?) peaks around 169°C were observed in epoxy resin, which shifted to lower temperature side on increasing the frequency. Addition of 2.91 wt% graphite shifted the tan ð›�? peaks towards higher temperature side by creating hindrances to the rotation of polymer dipoles. Addition of 2.91 wt% graphite leads to an increased relaxation time 𝜏 of dipoles in polysulphide epoxy from 1.44 Ã�? 10^-5-3.92 Ã�? 10^-5 (s) at 90°C by creating the hindrance to the rotation of dipoles.

[学科分类] 材料工程

[关键词] a.c. conductivity;graphite;epoxy.