Dynamic mechanical behavior and structure of polyurethaneimides

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Abstract
Dynamic mechanical behavior and X‐ray diffraction of two series of segmented polyurethaneimides (PUI) prepared either from poly(ethylene adipate) glycol (PEA), pyromellitic dianhydride (PMDA) and 4,4′‐diphenylmethane diisocyanate (MDI), or from PEA, PMDA, and a mixture of 2,4‐ and 2,6‐tolylene diisocyanate (TDI) were studied. All samples have a two‐phase structure of the soft polyester (PE) phase and hard polyimide (PI) phase. PI microdomains containing MDI units are semicrystalline, whereas those with TDI are crystalline only at highest contents of TDI. The storage modulus E′ increases with increasing fraction of the hard phase. The MDI‐containing hard phase has a stronger effect on E′ and also makes the plateau on the dependence of E′ on temperature more pronounced.