External impacts on structure and relaxation properties of thermotropic liquid crystal copolyester

Abstract

Abstract The methods of thermally stimulated depolarization (TSD) and X-ray diffraction analysis were used to study the impact of electric and temperature fields on the relaxation properties, structure, and molecular mobility of a liquid crystal (LC) copolymer based on polyethylene terephthalate (PET) and n-hydroxybenzoic acid (n – HBA). It was shown that polarization in the LC state besides the main relaxation transition leads to the formation of additional high-temperature maximum on current thermograms of thermally stimulated depolarization (TSD). The data of X-ray diffraction analysis indicate a change in the orientation of mesogenic units after polarization in an electric field. The results were explained by the combined action of electric and temperature fields on the conformational structure of the liquid crystal copolyester, namely, a change in the degree of crystallinity of the studied copolyester under the influence of external fields.