Molecular mobility and crystallinity in polytetramethylene ether glycol in the bulk and as soft component in polyurethanes

► PTMEG and PTMEG based PUs studied by Modulated DSC and two dielectric techniques. ► PTMEG of higher molecular weight exhibits more homogeneous crystallinity. ► Decrease of Mw of PU segments enhances microphase mixing and increases Tg. ► PTMEG segments of Mw = 2000 in PU crystallize after a spinodal decomposition process.