Submitted to: Journal of Biobased Materials and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2015
Publication Date: 6/18/2015
Citation: Finkenstadt, V.L., Fanta, G.F., Felker, F.C., Hornback, K., Selling, G.W. 2015. Structure-function properties of amylose-oleic acid inclusion complexes grafted with poly(methyl acrylate). Journal of Biobased Materials and Bioenergy. 9(2):258-265(8).
Interpretive Summary: In order to broaden the use of corn starch in consumer products, the starch is often modified. One method to modify starch is by attaching other polymers to it. For example, when poly(methyl acrylate) is attached to the starch, the resulting product, starch graftpoly(methyl acrylate), will have different properties than either material alone. Stach alone is a brittle polymer that is not fully utilized in part due to its elongation. Poly(methyl acrylate) is an inexpensive gummy polymer that has limited utility due to its tackiness. When the starch graftpoly(methyl acrylate) is formed, the material has good elongation and can be processed like other plastics using melt processing is not gummy. It was found that when smaller particles of starch were used, elongation can be dramatically increased. Physical properties are similar to those of polyethylene and yet the material is 50% bio-based. This information will be beneficial to manufacturers involved in the production of corn starch as well as those companies interested in producing biobased (corn) articles that can compete with articles made using petroleum based ingredients.
Technical Abstract: Spherulites, produced by steam jet-cooking high-amylose starch and oleic acid, were grafted with methyl acrylate, both before and after removal of un-complexed amylopectin. For comparison, granular high-amylose corn starch was graft polymerized in a similar manner. The amount of grafted and ungrafted poly(methyl acrylate) were similar for all starch-graft-poly(methyl acrylate) copolymers. Ribbons were extruded, and tensile properties were determined. Although extruded ribbons with similar tensile strength were obtained from the three starch-PMA graft copolymers, much higher values for elongation were obtained from the spherulite-containing copolymers. The graft frequency and molecular weights of grafted poly(methyl acrylate) showed an interesting correlation to the tensile elongation of the extruded sample.