Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 22, 2009
Publication Date: November 15, 2009
Citation: Jong, L. 2009. Effect of Hydrolyzed Wheat Gluten and Starch Ratio on the Viscoelastic Properties of Rubber Composites. Journal of Applied Polymer Science. 114(4):2280-2290. Interpretive Summary: Wheat gluten and starch are the protein and carbohydrate obtained from wheat flour. In many rubber related applications, rubber products are filled with reinforcement materials. Previously, we have used soy protein and soy carbohydrate to increase significantly the strength of rubber composites. The new development is to use different ratios of wheat gluten and starch to change the strength and flexibility of rubber composites. The results indicate that the rubber composites dominated by hydrolyzed wheat gluten exhibited similar mechanical properties as that of carbon black filled composites. This development will be of general interest and practical applications to technologists developing new rubber products and will be beneficial to wheat farmers by creating new markets for wheat products.
Technical Abstract: The hydrolyzed wheat gluten (WG) and wheat starch (WS) showed substantial reinforcement effects in rubber composites. Due to different abilities of WG and WS to increase the modulus of rubber composites, the composite properties can be adjusted by varying the ratio of WG and WS as a co-filler. The temperature dependent moduli indicated that WS and WG composites were less temperature dependent than carbon black (CB) composites. The temperature dependence of the co-filler composites increased with the increasing WG content. In poly(styrene-butadiene) matrix, WS had the greatest reinforcement effect, while WG and CB had a similar reinforcement effect. The co-filler composites showed a reinforcement effect between that of WG and WS single-filler composites. For fatigue and recovery properties, the initial structure of WS filler-related network was stronger and more resilient in the smaller strain region, but it broke down significantly in the larger strain region without much recovery. WG and CB, on the other hand, had a less elastic filler-related network structure in the smaller strain region, but had better recovery ability. The co-filler composites reflected the characteristics of the single filler composites. For the residual structures of these composites after the strain cycles, WG composites were the most elastic in the small strain region. For the co-filler composites, the composite structures became less elastic as the WS content was increased. 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 hydrolyzed WG-dominated composites exhibited viscoelastic behaviors similar to that of CB composites.