Physicochemical characteristics of glycerol-plasticized dextran/soy protein isolate composite membranes

This work deals with the preparation and characterization of in situ crosslinked dextran/soy protein isolate composite membranes as a function of increasing glycerol content. The surface morphology of the membranes, as evidenced from field emission scanning electron microscopy and atomic force microscopy, exhibited smoother surfaces with increasing glycerol content up to 30%. The wettability, color, and UV-blocking characteristics of the membranes were studied. The glycerol content also significantly influenced the water vapor transmission rate of the membranes, demonstrating diminishing membrane permeability with increasing glycerol content. In addition, the membranes presented an increase in water vapor loss up to 5h with glycerol content ranging from 10% to 30%, whereas a decrease in vapor loss has been elucidated with 40% glycerol. The influence of plasticization on the rheological properties of the composite fluid was investigated. Although the tensile strength and modulus decreased with increasing glycerol content up to 30%, a significant increase was observed beyond this due to the antiplasticizing effect of glycerol that is dominant at concentrations higher than 30%. A structural analysis of the membranes using attenuated total reflectance indicates an increase in the intensity of the OH stretching region with increasing glycerol content. Further, X-ray diffraction patterns showed a decrease in crystalline behavior up to 30% glycerol content, above which the antiplasticizing effect of glycerol was dominant. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43847.