Practical simulation and experimental measurement of liquid crystal polymer directionality during injection molding

Abstract

Liquid crystal polymers (LCP's) comprise a class of materials that derive favorable mechanical, chemical, and electrical behavior from long‐range molecular ordering. This unique microstructure gives rise to anisotropic bulk properties that can be problematic for industrial applications, and thus the ability to model the polymer texture is essential to the design of manufacturing processes for isotropic material production. Previous efforts to model LCP directionality have been primarily restricted to structured grids and simple geometries that demonstrate the underlying theory, but fall short of simulating the polymer flow and orientation through realistic manufacturing geometries. In this investigation, a practical methodology is proposed to simulate the 3D director field in full‐scale melt‐processing domains for the prediction of the bulk material orientation state. The hybrid approach utilizes separate simulations for the polymer flow and directionality, using commercial CFD software and a user‐defined post‐processing script, respectively. Wide‐angle X‐ray scattering is used to experimentally validate the directions and degree of order calculated by the model. It is shown that the model is capable of predicting not only the bulk orientation state but also the intricacies of the hierarchal structure produced during manufacturing. POLYM. ENG. SCI., 59:E414–E424, 2019. © 2019 Society of Plastics Engineers