The effect of steady flow fields on the isotropic–nematic phase transition of rigid rod-like polymers

In this paper we study the stability of steady state solutions to Doi’s kinetic equation for rigid rod-like polymers in an arbitrary flow field. It is found that for a certain range of concentration, the addition of flow to an isotropic phase can induce a transition to the nematic phase, if the flow rate exceeds a certain critical value. This critical flow rate decreases as concentration is increased. For phase transitions occurring in weak flow, exact solutions to this problem are calculated. Unlike the ‘‘free energy’’ approach, these calculations are not restricted to potential flows.