Date of Completion

10-26-2015

Embargo Period

10-25-2018

Keywords

Wheat Gluten, Brittleness, Water Absorption, Toughening, Crosslinking, Energy Damping, Composites

Major Advisor

Richard Parnas

Associate Advisor

Douglas Adamson

Associate Advisor

Radenka Maric

Associate Advisor

Serge Nakhmanson

Associate Advisor

Harris Marcus

Field of Study

Materials Science and Engineering

Degree

Doctor of Philosophy

Open Access

Campus Access

Abstract

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.

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