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

这笔赠款为一项研究提供了资金，该研究将实施新的建模策略来预测热致液晶聚合物(TLCP)注射成型过程中的取向发展。TLCP的优异性能与棒状分子在向列相液晶相中的自发有序性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成型工艺的前提。该模型将利用所谓的“多域”取向描述，便于与实验数据的直接比较。这项工作利用了与复合材料工艺建模中使用的纤维取向模型非常相似的方法。该计算程序将与先进的同步加速器实验相配合，以量化分子取向：(I)在注塑过程中实时进行取向的原位x射线散射测量，以及(Ii)一种新的非原位同步光谱分析技术，它提供了前所未有的注塑表面层内分子取向分布的三维表征。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工艺中定向发展的深入了解，以及预测建模工具的开发和批判性评估，应该会有利地影响这些材料的技术应用。更广泛的科学界将通过开发一种用于现场研究聚合物注射成型的新设备来服务。分配到这个项目的学生将学习尖端的实验和建模工具。最后，外展工作将吸引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向业界传播该项目的方法和结果。

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.