CONTINUUM DYNAMIC BEHAVIOR OF HOMOGENEOUS LIQUID-CRYSTALLINE POLYMERSUNDER THE IMPOSITION OF SHEAR AND MAGNETIC

An analysis of the dynamic behavior of polymeric liquid crystals is gi ven in terms of a second-rank order parameter tensor describing the or ientational state of the local microstructure. The continuum equations governing the dynamics of the material are analyzed under both steady -state and transient conditions for isotropic and liquid-crystalline f luids subjected to shear and magnetic fields. Analysis reveals that a great variety of dynamic behavior for liquid-crystalline materials can be accommodated within the framework of a continuum theory in terms o f a second-rank order parameter tensor, and that this dynamic behavior approximates well the orientational behavior obtained with the more c omplex distribution function theories. Under some conditions the. asso ciated theological behavior of the continuum theory exhibits discrepan cies in the normal stress behavior compared to theological calculation s based on the distribution function theory. For simultaneous applicat ion of shear and magnetic fields, both the direction and the strength of the magnetic field play a major role in determining the dynamic sys tem response. (C) 1995 Society of Rheology.