Dielectric characterization of a thermotropic liquid crystalline copolyesteramide: 1. Relaxation peak assignment

Dielectric relaxation analysis was carried out on the main chain thermotropic liquid crystalline copolyesteramide Vectra B950. The dielectric spectra of Vectra B950 show four relaxations, instead of three as cited in the literature. These correspond, from high to low temperature, to the glass transition, the rotation of hydroxynaphthoic acid moieties, the rotation of terephthalic acid moieties, and the combined rotation of terephthalic acid and aminophenol moieties. The combination of TSD and DMA analysis made it possible to distinguish between dipole and charge relaxations. Although the TSD and the dielectric results compare well for the low-temperature dipole relaxations, they are not directly comparable for the alpha relaxation. TSD experiments reveal that free charges have a significant influence on the cl relaxation.