Simulation and Experimental Measurement of Liquid Crystal Polymer Orientation During Injection Molding

MRS Advances ◽  
2018 ◽  
Vol 3 (39) ◽  
pp. 2311-2316
Author(s):  
Anthony Sullivan ◽  
Anil Saigal ◽  
Michael A. Zimmerman
Keyword(s):  
Liquid Crystal ◽  
Melt Processing ◽  
Engineering Properties ◽  
Liquid Crystal Polymers ◽  
Director Field ◽  
X Ray Scattering ◽  
Molecular Ordering ◽  
Orientation State ◽  
Degree Of Order ◽  
Good Agreement

AbstractLiquid crystal polymers (LCP’s) comprise a class of materials that derive desirable, but anisotropic, engineering properties from long-range molecular ordering. 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 realistic manufacturing geometries. In this investigation, a practical methodology is proposed to simulate the director field in full-scale melt-processing domains and wide-angle x-ray scattering (WAXS) is used to experimentally validate modeling results. It is shown that the model generates good agreement with experimental measurements of both the orientation state and degree of order.

Simulation of Liquid Crystal Polymer Directionality During Cast Film Extrusion

2018 ◽  
Author(s):  
Anthony Sullivan ◽  
Anil Saigal ◽  
Michael A. Zimmerman
Keyword(s):  
Liquid Crystal ◽  
Bulk Material ◽  
Hybrid Approach ◽  
Industrial Applications ◽  
Melt Processing ◽  
Liquid Crystal Polymers ◽  
Film Extrusion ◽  
Cast Film ◽  
Orientation State ◽  
Degree Of Orientation

Liquid crystal polymers (LCP’s) comprise a class of melt-processable materials that derive specialized mechanical, chemical, and electrical properties from long-range molecular ordering. This unique microstructure gives rise to anisotropic bulk behavior that can be problematic for industrial applications, and thus the ability to model the orientation state in the polymer is necessary for the design of isotropic material manufacturing processes. 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 realistic manufacturing geometries. In this investigation, a practical methodology is proposed to simulate the director field in full-scale melt-processing set-ups, specifically cast film extrusion, to predict the bulk material orientation state. The hybrid approach utilizes separate simulations for the polymer flow with commercial computational fluid dynamics (CFD) software, and the material directionality through a user-defined post-processing script. Wide-angle x-ray scattering (WAXS) is used to experimentally validate the simulated directionality during extrusion processing. It is shown that the model is capable of predicting both the direction and degree of orientation in the polymer resulting from processing, and the model produces strong agreement with experimental measurement of the polymer orientation state.

Structure-property-processing relationships in extruded liquid crystal polymer film

2021 ◽  
pp. 096739112110070
Author(s):  
Anthony Sullivan ◽  
Anil Saigal ◽  
Michael A Zimmerman
Keyword(s):  
Liquid Crystal ◽  
Industrial Applications ◽  
Practical Implementation ◽  
Liquid Crystal Polymers ◽  
Structure Property ◽  
Bulk Properties ◽  
Industrial Processing ◽  
Film Extrusion ◽  
Modeling Methodology ◽  
Orientation State

Liquid crystal polymers (LCPs) derive favorable mechanical, chemical, and electrical behavior from long-range molecular ordering. The microstructure gives rise to anisotropic bulk properties that are problematic for industrial applications, and thus the ability to model the polymer directionality is essential to the design of isotropic material manufacturing processes. This investigation proposes a modeling methodology to simulate the 3D director field in full-scale film extrusion geometries. Wide-angle x-ray scattering (WAXS) is used to validate the predicted orientation for a standard coat-hanger die, and is compared with macroscopic mechanical, thermal, and dielectric testing of LCP film to illustrate the morphological dependence of the polymer properties. The highly anisotropic orientation state resulting from cast film extrusion is both predicted by the model and confirmed experimentally, and this preferred orientation is shown to correlate with observed anisotropy in the bulk properties. Additionally, a practical implementation of the modeling tool is presented to simulate directionality in two alternative die geometries designed to improve bulk isotropy, and it is demonstrated that the model is capable of simulating the resulting order for large, irregular domains typical of industrial processing.

scholarly journals Dynamic tuning of the director field in liquid crystal shells using block copolymers

2020 ◽  
Vol 2 (3) ◽  
Author(s):  
JungHyun Noh ◽  
Yiwei Wang ◽  
Hsin-Ling Liang ◽  
Venkata Subba Rao Jampani ◽  
Apala Majumdar ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Block Copolymers ◽  
Director Field ◽  
Dynamic Tuning
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