TSD of Liquid Crystals in the Supercooled Nematic Phase

Abstract MBBA and EBBA are used to apply the techniques of thermally stimulated depolarization (TSD) to liquid crystals in their glassy state. The orientational mobilities of the butyl and methoxy resp, ethoxy group show significant differences compared to the crystalline phases. A small TSD band in MBBA at 69.5 K and in EBBA at 64.5 K probably comes from relaxations of the butyl group. A ten times stronger TSD band at 117.5 K resp. at 124 K is due to relaxations of the methoxy respect to the ethoxy group. Using the partial heating technique and the thermal sampling technique a detailed analysis of this band allows more insight into the distribution of reorientation enthalpies and relaxation times.

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