Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/16/2008
Publication Date: 3/22/2009
Citation: Jong, L. 2009. Reinforcement Effect of Alkali-Hydrolyzed Wheat Gluten and Shear-Degraded Wheat Starch in Carboxylated Styrene-Butadiene Composites. Paper No. POLY65.
Technical Abstract: Wheat gluten (WG) and wheat starch (WS) are the protein and carbohydrate obtained from wheat flours. Wheat gluten is not water soluble or dispersible due to its hydrophobic nature. To prepare wheat gluten dispersions, an alkali hydrolysis reaction was carried out to produce a stable aqueous dispersion. WG aggregates have a number and volume average size of ~0.3 and ~7 micrometers, respectively. The swollen size of WG aggregates can be further decreased by ultrasonic disruption to a number and volume average size of ~300 and ~380 nm, respectively. The swollen WS aggregates in aqueous dispersion had a number and volume average size of ~7 and ~24 micrometers, respectively. The WG, WS, or carbon black (CB) dispersions were coagulated with rubber latex to form composites. This study shows that WS and WG composites were less temperature dependent than CB composites. WS showed the greatest reinforcement effect, while WG and CB had similar effect. For fatigue and recovery properties, the initial structures of WS composites were more stable at the smaller strains, but they broke down at the larger strains without much recovery. WG and CB composites, on the other hand, had a less stable composite structure at the smaller strains, but had better recovery ability. For the residual structures of these composites after the strain cycles, WG composites were the most elastic in the small strain region. The extent of stress softening indicated WS composites had a significant structure deformation and were less elastic compared to WG and CB composites. This study shows that the alkali hydrolyzed WG composites exhibited viscoelastic behaviors similar to that of CB composites.