Microstructural lattice simulation and transient rheological behavior of aflow-aligning liquid crystalline polymer under low shear rates

A microstructural lattice simulation for textured liquid crystalline polyme r is carried out to predict rheological behavior, especially the stress evo lution after shear inception. It is based on a combination of two main conc epts: (i) the director in each cell of a supramolecular lattice has an orie ntation described by the minimization of total energy of director map, and (ii) the torque balance of each director under shear flow and anisotropic r elaxational shear moduli depends on the averaged orientation of the directo r map. By considering the interaction between the nearest-neighbor director s, the spatial orientational correlation is introduced and the spatial hete rogeneity, i.e., a polydomain texture, is generated simultaneously. For the start-up shear flow, the overshoot and the steady value of shear stress in crease and the former shifts toward a shorter time as the applied shear rat e increases. Also, the calculated stress evolution is compared with the exp erimental result of a thermotropic liquid crystalline poly(ester-imide).