Effect of the poly(oxytetramethylene)diol spacer length on some properties of liquid crystalline polyurethanes |
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Authors: | Barbara Szczepaniak,Kurt C. Frisch,Piotr Penczek,Jerzy Mejsner,Irena Leszczy ska,Ewa Rudnik |
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Affiliation: | Barbara Szczepaniak,Kurt C. Frisch,Piotr Penczek,Jerzy Mejsner,Irena Leszczyńska,Ewa Rudnik |
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Abstract: | Previous studies on liquid crystalline polyurethanes prepared from 4,4′-bis(2-hydroxyethoxy)biphenyl (BHBP) and 2,4-tolylene diisocyanate (TDI) were continued. In this article, a series of polyurethanes, which differ in the flexible spacer length and BHBP content is described. Poly(oxytetramethylene)diols of different molecular weights (PTMO, M n = 250, 650, 1000, 2000) were used as flexible spacers. The polyurethanes were investigated by DSC, polarizing microscopy, x-ray diffractometry, and IR spectroscopy. The molecular weight distribution was determined by GPC. The morphology of the polyurethanes was investigated by the SALS method. Partial replacement of BHBP by 25–75 mol % PTMO and the flexible spacer length influence the liquid crystalline properties, the phase transition temperatures, and the range of mesophase occurrence. © 1993 John Wiley & Sons, Inc. |
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Keywords: | main-chain liquid crystalline polymers thermotropic polyurethane spacer length effect |
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