Rheology of Semi-dilute Solutions of Calf-thymus DNA

We study the rheology of semi-dilute solutions of the sodium salt of calf-thymus DNA in the linear and nonlinear regimes. The frequency response data can be fitted very well to the hybrid model with two dominant relaxation times $\tau_0$ and $\tau_1$. The ratio $( \tau_0 / \tau_1) \sim 5$ is seen to be fairly constant on changing the temperature from 20 to $30^o\hspace{2mm}C$. The shear rate dependence of viscosity can be fitted to the Carreau model