Abstract
Abstract The influence of the type of chain length regulator on the molecular weight, mechanical properties and solution viscosity of poly(urethane ureas) (PUUs) was investigated. As a model, a PUU based on poly(oxytetramethylene)glycol, 4,4′-diphenylmethane diisocyanate, a mixture of ethylenediamine as chain extender and propylene-1,2-diamine as co-chain extender was used. The monoamines diethanolamine (DEA), ethanolamine (EA) and 3(5)-methylpyrazole (3-MP) were compared as chain length regulators. Additionally, model reactions between phenyl isocyanate, n-butylamine and the three monoamines were performed to obtain data about the reactivity and possible side reactions of this mixture. These investigations were carried out by quantitative h.p.l.c. analysis. The lower reactivity of 3-MP led to a minor increase in the molecular weights of the PUUs due to further NCO-conversion, whereas all the mechanical properties of the different polymers were nearly identical. In contrast to 3-MP, however, the application of DEA or EA gave significantly lower solution viscosities, obviously due to the hydroxyl groups of these agents.
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