Influence of polyurethane-based polycarbonate diols with different structures induced via polymer processing on their dielectric properties

This study was focused on the different conformations of polyurethane (PU)-based polycarbonates diols (PUC) that contributed to the dielectric properties, which was explained by the plot of temperaturevs. dielectric constant and loss, using the Vogel-Fulcher-Tamman-Hesse equation and Cole-Colt plots. The effect of the conformation and hard segment content was compared in terms of the dielectric properties. The PUCs with a cross-linked or linear conformation were both synthesized by the prepolymer method, varying the hard segment content from 23 to 48% by weight (wt%). As expected, increasing the hard segment content decreased the dielectric constant, since it created a rigid polymer chain in the PUCs. Nevertheless, it also caused interface polarization. The effect of the PU conformation had a greater effect on the dielectric constant than the hard segment content by weight. The linear conformation PUC clearly showed a higher dielectric constant, and frequency and temperature dependence than those of the cross-linked conformation PUC. beta-Relaxation and alpha-relaxation were the main relaxation processes found in the PUCs.