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Characterization of a two-phase starch-based polymeric system
With increasing demands for using agricultural materials in industrial applications to reduce the dependence on cruel oils and natural gases, starch has received a lot of attention. Starch molecules can be chemically modified to obtain properties similar to petroleum-based polymers. However, due to their inherent hydrophilic characteristics, after thermomechanical process such as extrusion, starch-based materials have low functional properties and cannot compete with other polymers. In this dissertation, starch acetate, a chemically modified hydrophobic polymer, was used as the base material to prepare extruded materials. ^ During extrusion, starch acetates were transformed, losing their original morphological properties, and resulting in direct effects on the functional and thermal properties of the final materials. With this information, it was possible to separate the effect from second phase materials on the final two phase starch system. ^ Research was conducted to prepare various extruded foams from starch acetates and other biopolymers. By blending starch acetates with biopolymers, some of the functional properties were increased while the preparation cost was reduced. On the other way, the improved functional properties suggested well-blended/homogeneous mixtures were obtained. ^ Detailed studies also were conducted to analyze the relationship between morphological and functional properties of processed two phase starch-based materials. Both starch acetate-cellulose and starch acetate-PLA (two phase systems) were well-mixed and no phase separation occurred, suggesting starch acetates had good miscibility with the other two biopolymers. Cellulose and PLA did not just functioned as fillers in the predominantly starch acetate systems, but their appearances also improve some of the functional properties. ^ Finally, macromolecular structural properties were examined using scanning electronic microscope. The starch acetate-cellulose foams showed the optimum hexagonal cell structures. This was the major reason why these foams had good functional properties. Meanwhile, post-extrusion steaming recovery of starch acetate-based extruded foams was discovered, to provide broader applications and reusability of the foams. ^
Guan, Junjie, "Characterization of a two-phase starch-based polymeric system" (2005). ETD collection for University of Nebraska - Lincoln. AAI3194115.