Collaborative Research: Thermal and Processing Effects on the Properties of Low Cost Thermotropic Copolyesters

该合作研究项目旨在加深对热致液晶聚合物(TLCP)加工的了解，从而降低目前广泛应用的障碍。这将通过对TLCP的熔体稳定性、流动行为和结构/性能进行协调研究来实现。一系列复杂的表征方法将被用于监测熔体在高温下的热稳定性，X射线散射方法将被用于研究分子取向(直接与TLCP的机械性能相关)在简单流动和与加工相关的复杂流动中的发展和命运。近年来，这些方法已被卓有成效地应用于具有纯科学意义的TLCP的“模型”，但该项目为使用这些技术对技术相关材料进行全面研究提供了第一次机会。为了将这些基本信息与产品性能相关联，将在X射线结果的指导下对通道流动斑块进行模制，并研究其形态和物理性能。这些材料用于商业应用，要求具有良好的加工性、充模精度、物理性能、尺寸稳定性和热稳定性。尽管TLCP前景看好，但其作为高强度/轻质材料的潜力可能得到充分发挥的许多应用领域尚未得到广泛应用。促成因素包括加工过程中熔体在高温下的热稳定性限制、成型过程中系统性的弱方向以及商业上可获得的TLCP的高成本。这项工作将以TLCP材料为特色，提供大幅降价的潜力(约3美元/磅)，从而直接解决成本这一核心问题。西北大学和MMI之间的合作为研究生和本科生提供了一个在最先进的表征工具和热分析方面获得经验的场所。

This Collaborative Research project is to develop an understanding of the processing of thermotropic liquid crystalline polymers (TLCPs) so that the current barriers to widespread applications are lowered. This will be accomplished through a coordinated study of melt stability, flow behavior, and structure/properties of TLCPs. An array of sophisticated characterization methods will be applied to monitor the thermal stability of the melt at high temperature, and x-ray scattering methods to study the development and fate of molecular orientation (directly related to mechanical properties of TLCPs) in both simple flows and complex flows of relevance to processing. These methods have been productively applied to 'model' TLCPs of purely scientific interest in recent years, but this project affords the first opportunity for a comprehensive study of a technologically relevant material using these techniques. To relate such fundamental information to product properties, channel flow plaques will be molded under protocols guided by the x-ray results, and their morphologies and physical properties studied.These materials are used commercially in applications requiring excellent processibility, mold-filling precision, physical properties, dimensional stability, and thermal stability. Despite considerable promise, TLCPs have yet to be broadly applied in numerous applications where their potential as high strength/low weight materials might be realized. Contributing factors include thermal stability limitations at high temperatures in the melt during processing, systematically weak directions in moldings, and the high cost of commercially available TLCPs. This work will feature a TLCP material that offers potential for dramatic price reductions (approximately $3/lb), thereby directly addressing the central issue of cost. The collaboration between Northwestern University and MMI provides a venue for graduate and undergraduate students to gain experience in state-of-the art characterization tools and thermal analysis.