Miscible blends of poly(ethylene oxide) and an amorphous copolyester-polyurethane

Blends of poly(ethylene oxide) (PEO) with an amorphous copolyester-polyurethane (PU) were prepared by casting from a common solvent. The polymers were found to be miscible and to show a single, composition dependent, glass transition temperature. The techniques used were DSC and optical and scanning electron microscopy. Optical and scanning electron microscopy revealed that blend samples prepared by solution casting crystallized with volume-filling spherulites up to a composition of 40/60 PEO/PU. DSC results showed that there existed crystals in the samples of high PEO content up to 10/90 PEO/PU. Observation of melting point depression of annealed melt-pressed films allowed determination of the B interaction parameter of the two polymers in the melt, using available theory. In order to obtain equilibrium melting point data, the Hoffman-Weeks procedure was employed to take into account the influence of crystal morphology. The value of B obtained was -3.42 cal/cm 3 ; the negative value is expected for miscible blends. © 1990.