Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 22, 2007
Publication Date: April 5, 2008
Citation: Jong, L. 2008. Dynamic mechanical properties of styrene-butadiene composites reinforced by defatted soy flour and carbon black co-filler. Journal of Applied Polymer Science. 108:65-75. Interpretive Summary: In a continuing effort to improve the value of soy products and to expand the use of renewable materials in industrial applications, we have focused research effort on the use of renewable soy products in the composite applications. To achieve balanced properties required for styrene-butadiene composites, mixtures of defatted soy flour (DSF) and carbon black (CB) were used to reinforce the composites. DSF has a lower material cost than carbon black. Previously, it was shown that DSF has a significant reinforcement effect in styrene-butadiene composites. The reinforcement effect was characterized by measuring the strength of the composites. The current development indicates a partial substitution of CB with DSF results in an increase in the strength and a reduced filler cost. This development will be useful to industries developing new rubber products and to soybean farmers by creating new markets for soybean products.
Technical Abstract: Carboxylated styrene-butadiene (SB) composites reinforced by a mixture of defatted soy flour (DSF) and carbon black (CB) were investigated in terms of their dynamic mechanical properties. DSF is an abundant renewable commodity and has a lower cost than CB. DSF contains soy protein, soy carbohydrate, and soy whey. Aqueous dispersions of DSF and CB were first mixed and then blended with SB latex to form rubber composites by freeze-drying and compression molding method. A 30% DSF reinforced composite exhibited a 230-fold increase in the shear elastic modulus compared with unfilled SB rubber, showing a significant reinforcement effect by DSF. Mixtures of DSF and CB at three different ratios were also investigated as co-fillers. Compared with the DSF composites, the recovery behaviors of the 30% co-filler composites after the eight consecutive deformation cycles of dynamic strain were improved, and were similar to that of 30% CB composite. The co-filler composites showed a greater elastic modulus than the CB reinforced composites within the strain range measured.