Structure–property relationships of polycarbonate diol‐based polyurethanes as a function of soft segment content and molar mass

Abstract

ABSTRACTSegmented thermoplastic polyurethanes (PUs) have been synthesized with polycarbonate diol as soft segment and 4,4′‐diphenylmethane diisocyanate and butanediol as hard segment. Two different series employing two different soft‐segment molar mass, 1000 and 2000 g/mol, and by changing the hard‐segment content from 32 to 67% have been investigated with the aim to elucidate the effect of the different content variations on the properties. Morphological, thermal, and mechanical properties have been studied by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), wide angle X‐ray diffraction, atomic force microscopy, tensile and tear strength, hardness, and specific gravity tests. Properties have been explained from the standpoint of miscibility between hard‐ and soft‐segment microdomains of the tailored segmented PUs through an exhaustive analysis. FTIR, DSC, and DMA measurements revealed that miscibility between hard and soft microdomains increases as the molar mass of the macrodiol decreases. An increase in hard‐segment content entailed the formation of larger hard domains with higher crystallinity what results in superior mechanical properties such as higher tensile stress and tear strength, and hardness. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41704.