Date of Completion
Wheat Gluten, Brittleness, Water Absorption, Toughening, Crosslinking, Energy Damping, Composites
Field of Study
Materials Science and Engineering
Doctor of Philosophy
Wheat gluten (WG) is the protein extracted from wheat flour and normally manufactured as an industrial by-product. WG is found to possess reasonable mechanical properties when processed into biodegradable plastic and thus has the potential to substitute some petroleum-based non-degradable plastics and composites matrix. Nevertheless, application of WG biodegradable plastics is restricted by two major disadvantages: brittleness and high water absorption. Brittleness causes WG materials to fail at strains as low as 1%, and high water absorption softens WG when exposed to water. In the current study, anhydride functionalized macromolecular cross-linkers are developed to construct a new intermolecular network structure that is able to efficiently blunt crack propagation to improve WG mechanical performance. Rubbery cross-linkers, such as polyethyl acrylate-co-maleic anhydride (PEA-MA), blunt crack propagation and have strong energy damping capabilities, leading to a large improvement in mechanical properties. Meanwhile, the network structure restricts WG from swelling to reduce the high water absorption. Characterization techniques, such as FTIR, DSC, TGA, SE-HPLC, DMA, NMR, and mechanical testing are performed to determine the new molecular structure, energy damping and performance of the WG. Among all the blends, WG/PEA-MA achieves so far the highest mechanical properties in the field, with strength, strain, and toughness improved by 110%, 255%, 880%, respectively, and water absorption ratio is greatly reduced from 115% to 50%. WG/PEA-MA blend has mechanical performance better than polystyrene, therefore making it promising for applications such as non-degradable plastics and composite matrices.
Diao, Cheng, "Wheat Gluten Biodegradable Plastics and Biocomposites" (2015). Doctoral Dissertations. 941.