Numerical simulation of liquid crystalline polymer flow into two‐dimensional thin cavity moulds

Abstract

SUMMARYIn this paper, flows of liquid crystalline polymers into two-dimensional thin cavity moulds are simulated. The flows are modelled by Ericksen-Leslie equations of motion in the high viscosity limit. An elliptic pressure equation is derived under Hele-Shaw approximations, and the non-isothermal natures of the flow are modelled. The equations are solved using the finite-difference technique. A new boundary-mapping technique is developed in this study to solve the difficulty in the finite-difference treatment of arbitrarily shaped boundaries, which possess no natural coordinate system. This new method avoids the difficult mesh control in the body-fitted mapping process and makes the mapping process easy to implement. It can also solve the problems caused by the uneven distribution of grid nodes in the traditional body-fitted mapping technique.

On the banded texture and nematic elasticity in a thermotropic liquid crystalline polymer. In situ optical microscopy and light scattering

“…The flow behavior of LCPs is quite complex end efforts to understand the flow behavior and control the microstructure are being carried out. [18][19][20][21][22][23][24][25][26] It has also been reported that after shearing and orienting the polydomain texture the defect texture is not eliminated and this rapidly relaxes to a disordered state after cessation of shear, sometimes through a so-called banded texture. 2 In this study the optical textures during and after cessation of shear flow were studied by in situ optical microscopy and light scattering.…”

“…The polydomain texture and the difficulty to obtain a monodomain even under prolonged thermal annealing has prevented thermotropic LCPs to find optical applications, for example, polarizers or displays. The flow behavior of LCPs is quite complex end efforts to understand the flow behavior and control the microstructure are being carried out 18‐26 . It has also been reported that after shearing and orienting the polydomain texture the defect texture is not eliminated and this rapidly relaxes to a disordered state after cessation of shear, sometimes through a so‐called banded texture 2…”

Shear‐induced textures and viscoelasticity in the nematic and isotropic phase of semiflexible thermotropic polymers. A rheo‐optical study

“…Admittedly, the flow behavior of thermotropic polymers is complex and remains challenging. It is believed these results will further our understanding of nematic director and texture evolution under complex flow patterns 44‐48 …”