Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 27, 2009
Publication Date: June 24, 2009
Citation: Fanta, G.F., Salch, J., Felker, F.C., Shogren, R.L. 2009. Adsorption of Polyethylene from Solution onto Starch Film Surfaces. Journal of Applied Polymer Science. 114(3):1840-1847. Interpretive Summary: In this research, we discovered a simple process for applying thin, protective coatings of water-repellent polyethylene plastic to the surfaces of starch films. These findings are important because films and other consumer articles prepared from biodegradable starch are water sensitive, thus limiting many of their potential uses. This investigation shows that when polyethylene is dissolved in hot organic solvents and starch films are placed in the hot solutions, the dissolved polyethylene separates from solution and becomes attached to the starch film surface when the solutions are slowly cooled. These results will expand the range of end-use applications for biodegradable starch-based products, thus reducing the negative impact of non-degradable plastics on the environment.
Technical Abstract: Starch films were prepared by jet cooking aqueous dispersions of high-amylose starch and then allowing the jet cooked dispersions to air-dry on Teflon surfaces. When the starch films were immersed in 1 % solutions of PE in 1-dodecanol, dodecane and xylene at 120º C and the solutions were allowed to slowly cool, PE precipitated from the solutions and adsorbed onto the starch film surfaces. FTIR spectroscopy was used to estimate the µg of PE adsorbed per cm2 of starch film. PE was preferentially adsorbed onto the film side that was in contact with the Teflon surface during drying. The amount of PE adsorbed ranged from about 8 to 45 µg/cm2 and depended upon the solvent used and the final temperature of the cooled solution. SEM of starch film surfaces showed discontinuous networks of adsorbed PE on the Teflon side and widely spaced nodules of adsorbed PE on the air side. NMR analysis showed that the PE adsorbed onto the starch surface was more linear and/or had a higher molecular weight then the starting PE. Possible reasons for selective adsorption of PE onto the Teflon side of the starch film surface were considered.