Measurement of the Viscoelastic Coefficients of Main-Chain Nematic Polymers by an NMR Technique

Abstract

We propose a simple NMR technique, and the underlying theory, to evaluate, with high accuracy, four out of the five viscosity coefficients and the ratio $\frac{{k}_{33}}{{k}_{11}}$ of the bend to splay Frank elastic constants, in nematic polymers. Quantitative data on the viscosities ${\ensuremath{\gamma}}_{1}$, ${\ensuremath{\alpha}}_{1}$, ${\ensuremath{\alpha}}_{2}$, and ${\ensuremath{\eta}}_{c}$ and the ratio $\frac{{k}_{33}}{{k}_{11}}$ are given for the first time for a thermotropic nematic polymer. The material studied is poly (4,4\ensuremath{'}-dioxy-2,2\ensuremath{'}-dimethyl azoxybenzenedodecanediyl), a linear polyester usually labeled DDA9.