Molecular mobility and phase transitions in a liquid crystalline polymer studied by dielectric techniques

The mechanisms of molecular mobility and of phase transitions in a thermotr opic, comb-shaped, side-chain liquid crystalline polymer (LCP), poly-(epsil on -acryloyloxycaproyloxy-phenyl)-n-butoxybenzoate (PABB) were studied by d ielectric techniques (dielectric relaxation spectroscopy, DRS, and thermall y stimulated depolarization currents, TSDC). Two subglass secondary relaxat ions, beta and gamma, were observed in TSDC measurements, at about -100 and -150 degreesC, respectively. The beta relaxation, as well as, the alpha re laxation, associated to the glass transition, were studied by DRS.