Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/26/2004
Publication Date: 8/22/2004
Citation: Selling, G.W., Sessa, D.J. 2004. Effect of orientation on physical properties of zein based films[abstract]. American Chemical Society. p.45.
Technical Abstract: It has been reported that very little orientation takes place when processing zein (the main corn protein) into films or fibers. In polymers of synthetic origin, orientation has been observed after processing and many technologies have been developed to mitigate the resulting changes in properties that orientation induces. Work was performed using zein blends having 10 to 20% tri(ethylene) glycol and 7% water as plasticizers and processed on a Brabender single screw extruder to provide pellets. These pellets were used as the feed using the same extruder fitted with a ribbon die to produce a 2 inch ribbon. The physical properties of the ribbons were measured in the machine, transverse and 45' directions. It was found that the tensile strength and elongation were always highest when measured in the machine direction, illustrating that orientation is taking place. Upon comparison with un-orientated compression molded bars from the same formulations, the tensile strengths were similar but the elongations of the ribbons were significantly lower. When ribbon samples were ground and then compression molded, tensile strength was not affected, however, elongation increased to the same level as seen in the un-orientated molded bars. Microscopic analysis using cross polarized light of the ribbon shows that the ribbon is birefringent. IR spectra were obtained using polarized light. The spectra showed small differences in the carbonyl region when taken in the machine and transverse directions. When the surface layer of the ribbon was removed, the spectra in the two directions had no differences, illustrating that orientation occurs mainly on the surface of the ribbon.