Film-forming polymers from distillers' grains: structural and material properties

Hemicelluloses are promising biopolymers for substituting petroleum-based polymers. Distillers' grains (DG), a residual product from the dry grind ethanol industry, has a high hemicellulose and low lignin content making it an interesting feedstock as a low-cost source of hemicelluloses. This study fractionated DG into an alkali-soluble hemicellulose-rich polymer (DG-HC) and an alkali-insoluble residue (DG-AI). Chemical and 2D-NMR analyses suggested that DG-HC was rich in arabinoxylans, whereas DG-AI was more rich in glucans, along with crude proteins and fat. The DG-HC was made into stand-alone films or thin film coatings on paper, and evaluated by DSC, TGA, FT-IR, corrected water vapor transfer rate and tensile strength. Created DG-HC films were stiff with a Tg of about 174 °C. When coated onto paper, DG-HC can effectively increase paper dry and wet tensile strength. The residual DG-AI was characterized showing good potential for animal feed, having approximately 95% in vitro true dry matter digestibility.