| Popis: |
The specific features of the rheological properties of lyotropic liquid crystal systems are demonstrated, using aqueous solutions of propoxycellulose as an example. These properties include the existence of maxima on the plots of viscosity, elastic strain, normal stresses, and dynamic modulus against the concentration. These features are generally observed at concentrations corresponding to the appearance of the liquid crystal phase, although, in the case of elastic strain, the maximum is displaced into the region of higher concentrations. Accumulation of the liquid crystal phase is accompanied by an increase in non-linearity of the mechanical behaviour. The correlation between the static and dynamic characteristics is thus impaired. In the case of completely liquid solution the first difference in the normal stresses becomes negative. |
