DIELECTRIC-RELAXATION OF LC-THERMOTROPIC POLY(ESTER IMIDE)S

Two different series of poly(ester imide)s, which are distinguished fr om each other in the orientation of the ester Linkages and show well-d ifferentiated thermotropic behavior, are investigated by means of mode l calculations and dielectric relaxation spectroscopy. Model calculati ons show that the orientation of the ester linkages has a strong influ ence on the rotational energy barriers. The dielectric relaxation spec tra of both series shows three relaxation regions in the temperature r ange between 100 and 400 K that have been identified as the alpha-, be ta- and gamma-relaxation processes. A difference of about two orders o f magnitude between the characteristic rates of the gamma-relaxation i s the main feature observed in the dielectric response. However, the b eta-relaxation shows very similar behavior for both series. The differ ences in the relaxation behavior in the solid state are interpreted on the basis of the rotational barriers deduced from the model calculati on results. (C) 1997 John Wiley & Sons, Inc.