Vogel-fulcher dependence of relaxation rates in a nematic monomer and elastomer
Dielectric relaxation spectroscopy is used to study the relaxation processes in a nematic monomer and the corresponding cross-linked polymer nematic liquid crystal (elastomer). In the frequency window 10 mHz to 2 GHz the monomer liquid crystal shows a single relaxation whereas the polymer exhibits three relaxation processes, two of which are quantitatively analyzed. The temperature dependence of relaxation times in both the monomer and polymer follows a Vogel-Fulcher behavior. The relaxation processes are identified with specific molecular motions and activation energies are calculated in a linear approximation for comparison with literature data.
Shenoy
D
Code 6900, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA.
Filippov
S
Aliev
F
Keller
P
Thomsen
D
Ratna
B