Submitted to: Journal of Elastomers and Plastics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/11/2010
Publication Date: 5/1/2011
Citation: Peterson, S.C., Jong, L. 2011. Effect of shearing on the reinforcement properties of vital wheat gluten. Journal of Elastomers and Plastics. 43(3):191-205. Interpretive Summary: In this research vital wheat gluten, a renewable agricultural product, was examined to see if it would make an effective filler. A filler is any cheap material that can be added to rubber to make it stronger, more elastic, a different color, or change some other material property. Currently the dominant filler in the rubber market is carbon black, a byproduct of the petroleum industry. If vital wheat gluten can perform as a substitute for carbon black, we would be replacing a fossil fuel product with a renewable one. This research clarified that in wheat flour, which contains starch and vital wheat gluten, it is the wheat starch that does the best job of rigid reinforcement to the overall composite, but small concentrations of vital wheat gluten-filled composites outperformed their carbon black-filled counterparts in many material properties suited for more rubbery, elastic-type applications.
Technical Abstract: An aqueous dispersion of vital wheat gluten and styrene-butadiene rubber was subjected to high-shear mixing in an attempt to reduce the aggregate size and enhance filler-matrix interactions with the goal of improving the reinforcement properties of the overall composite. Composites were formulated using 10-40% vital wheat gluten by mixing aqueous suspensions of the gluten and rubber, then freeze-drying and compression molding the resulting composite. Rheological experiments indicated that vital wheat gluten reinforced the rubber up to a factor of roughly 34. Subjecting the gluten suspension to high shearing reduced the particle size from approximately 5.2 to 4.5 'm, and 16 minutes was the optimum shearing time since shearing the dispersions longer did not result in any additional size reduction. Composites with 10% vital wheat gluten have good potential in applications requiring high elasticity since they were equal to or better than the carbon black control in terms of Young’s modulus, percent elongation, and toughness. Isolated vital wheat gluten was studied in order to determine its relative merit as one of the two reinforcing components of wheat flour (the other being wheat starch), and its reinforcing ability was a factor of 10 weaker than wheat flour, indicating that wheat starch is a much more effective biomaterial filler in terms of rigidity, but vital wheat gluten may be more suitable for applications requiring more elasticity.