Dielectric properties of poly(triethylene glycol p,p′-bibenzoate-co-(R)-(+)3-methyl adipate)

In this study, a copolyester of poly(triethylene glycol p,p′-bibenzoate-co-(R)-3-methyl adipate) was prepared. The mesophase texture, the thermal and dielectric properties (a.c.-dynamical as well as thermostimulated depolarization currents) were studied. X-ray diffractograms reveal a relatively stable mesophase smectic Sc, whereas DSC shows on heating only the glass transition and the endotherm due the isotropization of the mesophase. Dynamic dielectric measurements show a broad sub-Tg relaxation together with an α loss peak (associated with the glass transition) overlapped with a significant conductive contribution. After separating this contribution from the dipolar component of the dielectric loss, we have modeled the relaxation according to classical empirical models. Thermostimulated depolarization currents also show three relaxations. The fine structure of these relaxations is analyzed by the thermal sampling technique.