Viscoelastic Properties of Low Temperature Thermotropic Liquid Crystalline Polymers

Abstract

Main-chain type thermotropic liquid crystalline polymers HPC-P having lower liquid crystalline temperature were obtained by esterification of hydoxypropyl cellulose. Two different samples were obtained, the one is HPC-P(l) having DS = 2.4 and another one is HPC-P(2) having DS = 2.8. Logarithmic curves of dynamic modulus(G') and loss modulus(G') against frequency obtained at different temperatures within liquid crystalline temperature range can be superposed to obtain a single composite curve for both samples. The composite curves for G' show lower frequency side plateau(Ca. 300 dyne/cm²). The log G' against temperature curves for both samples decrease with increasing temperature upto transition temperature and then increase upto T_C and then decrease again with increasing temperature above T_C showing maxima at around T_c.