Evaluating corn starch and corn stover biochar as renewable filler in carboxylated styrene–butadiene rubber composites

Abstract

Corn starch, corn flour, and corn stover biochar were evaluated as potential renewable substitutes for carbon black as filler in rubber composites using carboxylated styrene–butadiene as the rubber matrix. Previous work has shown that starch-based fillers have very good reinforcement properties at the expense of brittleness in the final rubber composite. In an attempt to alleviate this, starch was blended with corn stover biochar; the biochar does not have as good reinforcement properties but makes composites that are less brittle. It was found that carboxylated styrene–butadiene rubber composites filled with 10% (by weight) corn starch or a 3:1 blend of corn starch:biochar had better reinforcement, tensile strength, elongation, and toughness than the corresponding carbon black-filled control sample. These renewable fillers therefore show good potential in replacing carbon black filler for applications utilizing more ductile styrene–butadiene rubber composites.