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Several polyurethanes were prepared from poly(ethylene adipate) glycol, 4,4′‐diphenylmethane diisocyanate (MDI), and 1,4‐butanediol. The overall NCO/OH ratio was allowed to vary from 0.94 to 1.21. Thus, the obtained elastomers differed in the amount of allophanate groups and perfection of microphase separation. These effects were studied by dielectric and pulsed NMR techniques. The results show that quite subtle effects concerning molecular mobility and its restriction due to interfacial region, perfection of the separation, and inadequacy of thermomechanical measurements can be investigated in the presented way.
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W. Nierzwicki (1985) studied this question.
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