372588 Orientational Order of Rheologically Modified Main Chain Liquid Crystalline Polymers Processed By Multilayer Coextrusion
Orientational Order of Rheologically Modified Main Chain Liquid Crystalline Polymers Processed by Multilayer Coextrusion
Zhenpeng Li1, Zheng Zhou2, Shannon Armstrong2, Eric Baer2, Donald R. Paul1, Christopher J. Ellison1
1 McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
2 Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH, 44016, USA
Liquid crystalline polymers (LCPs) have been considered for potential applications as barrier films and high performance membranes due to their extraordinary barrier properties and chemical resistance. However, LCPs usually possess extremely low viscosities, which presents a challenge for implementing them into multilayer coextrusion due to the mismatch of their viscosities with other film components. In this study, a commercial grade diepoxy reagent was used to modify the rheological properties of a thermotropic main chain LCP. The effects of diepoxy concentration and reaction time on the resulting melt viscosity and liquid crystal structures of the LCP were investigated. High quality multilayer films were fabricated by coextruding the rheologically modified LCP with polypropylene-graft-maleic anhydride. Additionally, the orientational order of the LCP in the multilayer films was studied by polarized infrared spectroscopy and x-ray diffraction. It was found that the LCP chains tend to orient perpendicular to the extrusion direction instead of aligning along the shear direction, which was ascribed to a ‘log-rolling’ effect during processing.
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