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

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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.