Vogel-Fulcher dependence of relaxation rates in a nematic monomer and elastomer

Dielectric relaxation spectroscopy is used to study the relaxation processe s in a nematic monomer and the corresponding cross-linked polymer nematic l iquid crystal (elastomer). In the frequency window 10 mHz to 2 GHz the mono mer liquid crystal shows a single relaxation whereas the polymer exhibits t hree relaxation processes, two of which are quantitatively analyzed. The te mperature dependence of relaxation times in both the monomer and polymer fo llows a Vogel-Fulcher behavior. The relaxation processes are identified wit h specific molecular motions and activation energies are calculated in a li near approximation for comparison with literature data.