Optimization of Electrical Conductivity, Dielectric Properties, and Stress Relaxation Behavior of Conductive Thermoplastic Vulcanizates Based on ENR/COPA Blends by Adjusting Mixing Method and Ionic Liquid Loading

Abstract

Conductive thermoplastic vulcanizates based on epoxidized natural rubber (ENR) and copolyamide (COPA) blends were prepared using two alternative mixing stages to incorporate MWCNTs: after or before dynamic vulcanization (i.e., ADV or BDV, respectively). Effects of ionic liquid (IL) loading on properties of the blends were also studied. The results indicated that both ADV and BDV mixing preferentially localized MWCNTs in the COPA phase. However, with BDV mixing some of the MWCNTs also resided in ENR domains. The TPVs made with BDV showed higher electrical conductivity, dielectric properties, and superior stress relaxation behavior relative to those prepared by ADV. This might be due to better dispersion of MWCNTs in both phases of the blends. In addition, the electrical and dielectric properties were improved by the IL in a dose dependent manner with the IL loading. However, the IL reduced stress relaxation of the TPVs due to its plasticizing effect.