Polymer, 2019, vol 175pp. 186-194
DOI:10.1016/j.polymer.2019.05.010
Abstract
DMC-derived poly (ether urethanes) were prepared via isocyanate-free route. The transurethanization reaction of the non-isocyanate route needs higher temperature as compared with the traditional route. There may be some unknown side reactions under high temperature which lead to changes in chemical structure and subsequent thermal and mechanical properties of the novel DMC-derived non-isocyanate polyurethanes (NIPUs). Two 1,6-hexamethylene diisocyanate based polyurethanes (HDIPUs) were prepared as a control. HDIPUs possessed a higher melting point and better mechanical properties than NIPUs. In order to find out the causes of the difference in their thermal and mechanical properties, the structure, crystallization behavior, morphology and microphase separation behavior of NIPUs and HDIPUs were systematically studied and compared in this work. It was found that the structural distinction between NIPUs and HDIPUs was originated from the hard segments. The urea content in the hard segments of NIPUs was much higher than that of HDIPUs. The formation of urea groups was explained by the side reactions during the transurethanization process of NIPUs. Due to the random insertion of urea groups on the hard segments of NIPU, the strength of hydrogen bonding between hard segments and the crystallinity of the hard phase were lower than those of HDIPU. Therefore, the compatibility between the hard phase and the soft phase of NIPU was increased, resulting in poor thermal and mechanical properties.
