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

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 ${\gamma }_1$, ${\alpha }_1$, ${\alpha }_2$, and ${\eta }_c$ 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′-dioxy-2,2′-dimethyl azoxybenzenedodecanediyl), a linear polyester usually labeled DDA9.