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Abstract Polymer film blends of hydroxypropyl methylcellulose (HPMC) and hydroxypropyl starch (HPS) were produced with an incorporation of three different plasticizers, including polyethylene glycol (PEG), glycerol and 1, 2-propylene glycol (PG) respectively, and the influence of these plasticizers were compared and studied by X-ray Diffraction (XRD), small angel X-ray Scattering (SAXS), optical microscope and dynamic mechanical analysis (DMA). Results showed that multi-scale structure of the blends were greatly affected by the plasticizers and therefore caused significant changes in mechanical properties. In the course, blends with glycerol presented lamellar structure rather than self-similar structure. Moreover, crystalline degree was increased with an order of glycerol > PEG > PG, whereas the compactness of amorphous region of all samples was decreased by PEG and PG. [ABSTRACT FROM AUTHOR]

Since hydroxypropyl methylcellulose (HPMC) is a thermal gel while hydroxypropyl starch (HPS) is a cool gel, their blends show some unique and interesting behaviors of phase transitions and microstructures, which control their performances. This work focused on the effect of processing conditions on the microstructure and mechanical properties of these blends with various ratios of HPMC/HPS, in particular for incubation and drying conditions. To clearly identify the changes of starch phase in such blending system, the technique of dyeing HPS with iodine was developed and used. Rheometer, small angel X-ray scattering (SAXS), X-ray diffraction (XRD), dynamic mechanical analysis (DMA) and mechanical testing apparatus were used to study the changes of microstructure and the relative properties of the blending gels and dried films incubated at different temperatures. It was found that the higher incubation temperature resulted in higher storage modulus, more solid-like behavior and more compact self-similar structure of the blending gel. Moreover, the films prepared from the gels dried at high temperature showed higher crystalline degree and more compact amorphous structure, and therefore result in increasing tensile strength and modulus but decreasing elongation. [ABSTRACT FROM AUTHOR]