Collaborative Research: Microstructural Modeling and Synchrotron Studies of Orientation Development in Injection Molding of Liquid Crystalline Polymers

该基金为一项研究提供资金，该研究将实施新的建模策略，以预测热致液晶聚合物（TLCPs）注射成型过程中的取向发展。tlcp的优异性能与向列液晶相中棒状分子的自发有序以及随后的加工对分子取向状态的影响密切相关。预测和控制加工过程中分子取向的演变是优化TLCP成型的先决条件。建模将利用所谓的“多域”方向描述，这有助于与实验数据进行直接比较。这项工作利用了与复合过程建模中使用的纤维取向模型的密切类比。该计算程序将与尖端同步加速器实验相协调，以量化分子取向：(i)在注射成型周期中实时的原位x射线散射取向测量，以及（ii）一种新型的非原位同步加速器光谱技术，该技术提供了前所未有的3d表征分子取向分布在模具表层。该项目将在技术、科学基础设施和人力资源方面产生广泛影响。对TLCP加工中取向发展的深入了解，以及预测建模工具的开发和关键评估，将对这些材料的技术应用产生积极影响。更广泛的科学界将通过开发一种用于聚合物注射成型原位研究的新设备来服务。被分配到这个项目的学生将学习最前沿的实验和建模工具。最后，外联工作将吸引来自四年制大学的本科生、教师和教职员工参与该项目，并利用密歇根分子研究所的独特地位，将该项目的方法和结果传播给工业界。

This grant provides funding for a study in which new modeling strategies will be implemented to predict orientation development during injection molding of thermotropic liquid crystalline polymers (TLCPs). The excellent properties of TLCPs are intimately linked to the spontaneous ordering of rodlike molecules in the nematic liquid crystalline phase, and the subsequent impact of processing on the molecular orientation state. Prediction and control over the evolution of molecular orientation during processing is a prerequisite for optimized fabrication of TLCP moldings. The modeling will exploit a so-called 'polydomain' description of orientation which facilitates direct comparisons to experimental data. This effort is exploits a close analogy with fiber orientation models used in composite process modeling. The computational program will be coordinated with cutting edge synchrotron experiments to quantify molecular orientation: (i) in situ x-ray scattering measurements of orientation in real time during the injection molding cycle, and (ii) a novel ex situ synchrotron spectroscopy technique that offers unprecedented 3-D characterization of the molecular orientation distribution within the surface layer of moldings.This project will have broad impact in technology, scientific infrastructure, and human resources. Improved insights into orientation development in TLCP processing, as well as development and critical evaluation of predictive modeling tools, should favorably impact the technological application of these materials. The broader scientific community will be served by development of a new apparatus for in situ studies of polymer injection molding. Students assigned to this project will learn cutting-edge experimental and modeling tools. Finally, the outreach efforts will engage undergraduate students, teachers and faculty from 4-year universities in the project, and exploit Michigan Molecular Institute's unique position to disseminate the methods and results of this project to industry.