Submitted to: Composites Part A Applied Science and Manufacturing
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/4/2006
Publication Date: 2/1/2007
Citation: Jong, L. 2007. Effect of soy spent flakes and carbon black co-filler in rubber composites. Composites Part A Applied Science and Manufacturing. 38(2):252-264. Interpretive Summary: Soy spent flakes (SSF) is a plentiful, renewable material from the waste stream of commercial soy protein extraction. SSF contains mostly soy carbohydrate. In many rubber related applications, rubber products are filled with reinforcement materials. Currently, SSF has little commercial value. Previously, we have found that the elastic moduli of SSF reinforced rubber composites are greater than that of carbon black (CB) reinforced composites, but the SSF reinforced composites have less than desired recovery behaviors after they are deformed. In the current research, a mixture of SSF and CB is used as a reinforcing filler. The reinforcement effect is characterized by dynamic mechanical methods. The results show that the substitution of CB with 50% to 75% of SSF yields a greater elastic modulus than that of the CB composites; and the co-filler composites have recovery behaviors similar to that of the CB composites. This development will have practical use for technologists developing new rubber products, and will be useful to soybean farmers by creating new markets for soybean products.
Technical Abstract: Rubber composites reinforced by a mixture of soy spent flakes (SSF) and carbon black (CB) are investigated in terms of their viscoelastic properties. Soy spent flakes is a plentiful, renewable material from the waste stream of commercial soy protein extraction. SSF contains mostly soy carbohydrate. Dry SSF increases rubber modulus significantly. The aqueous dispersions of SSF and CB were first mixed and then blended with styrene-butadiene latex to form rubber composites by a freeze-drying and compression molding method. The mixtures of SSF and CB at three different ratios are investigated as co-fillers. A 30% co-filler reinforced composite exhibits about a 100 times increase in the shear elastic modulus compared with unfilled SB rubber, showing a significant reinforcement effect by the co-filler. Compared with the SSF composites, the recovery behaviors of the co-filler composites after the eight consecutive deformation cycles of dynamic strain are improved and are similar to that of the CB composites. The comparison of viscoelastic properties of the composites prepared by freeze-drying and casting methods indicates that the composites prepared by the freeze-drying method have a lower elastic modulus, but have a better recovery behavior due to its polymer mediated filler network structure. The co-filler composites with 50% to 75% substitution of CB by SSF have a greater elastic modulus than the CB reinforced composites.