Location: Plant Polymer Research
Title: Polymer composites prepared from heat-treated starch and styrene-butadiene latex Authors
Submitted to: Journal of Elastomers and Plastics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 13, 2014
Publication Date: N/A
Interpretive Summary: Rubber composites are made by using various blends of rubber with heat-treated starches. Heat-treated starches act as filler material, which makes a much stronger composite. Before blending with the rubber, the starch was pre-cooked at various temperatures, which makes the starch molecules swell, disintegrate, and become smaller molecules as the heating temperature was raised. A dramatic increase in the mechanical strength of the produced composites was observed, and the result was explained by the structural variation of the cooked starches. This work would impact the food and rubber processing industries, and could bring about the production of strong rubber composites using heated starch, which is cheap and renewable, and reduce the use of carbon black, which is obtained from the burning of fossil fuels.
Technical Abstract: Thermoplastic starch/latex polymer composites were prepared using styrene–butadiene (SB) latex and heat-treated cornstarch. The composites were prepared in a compression mold at 130 °C, with starch content 20%. An amylose-free cornstarch, waxy maize, was used for this research and the heat treatment range was from ambient to 170 °C. The heat-treated starch was characterized by Optical Microscopy, Dynamic Light Scattering (DLS), and Size Exclusion Chromatography (SEC). The composites were characterized by mechanical analysis (stress-strain) and by Scanning Electron Microscopy (SEM). The mechanical test of composites revealed a dramatic increase in the modulus and tensile strength when the gelatinized starch was incorporated. When the starch was not gelatinized, starch did not contribute to the increase in the modulus and tensile strength because of its small surface area, thus weak interaction with matrix. The reinforcing effect of starch as filler was reduced as the heating temperature of starch was increased to higher than 120 °C. The variation of reinforcement effect of heat-treated starch as filler was explained by the interaction between starch and matrix material, latex.