Miscibility and morphology of kefiran/waterborne polyurethane blend films

Biodegradable blends of kefiran with various contents (10–40 wt%) of waterborne polyurethane were successfully synthesized via the casting method. When waterborne polyurethane content is lower than 30 wt%, good compatibility and miscibility were observed; otherwise, phase separation occurs between them. These phenomena can be attributed to intermolecular interactions, which were confirmed by Fourier transform infrared, X-ray diffraction, differential scanning calorimetry analysis, and scanning electron microscopy. Compared with kefiran film, the blends increased in thickness, tensile strength, elongation at break, yellowness, and opacity when the waterborne polyurethane content was increased. Meanwhile, the water vapor permeability and moisture absorption significantly decreased (p < 0.05).