Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/21/2010
Publication Date: 6/7/2010
Citation: Woods, K.K., Sessa, D.J., Mohamed, A. 2010. Melt processing of Zein with Polyvinylprrolidone and Cloisite**R Nonoclay to improve tensile properties [abstract]. Corn Utilization and Technology Conference, June 7-9, 2010, Atlanta, GA. Interpretive Summary:
Technical Abstract: Zein, the predominant prolamine in corn, is one of the potential major co-products of the bioethanol industry. Historically, it was used predominantly in the coatings and textile industries (1). In the 1950’s, though, petroleum-based products became more cost effective and zein fell out of favor. The current focus on bioethanol production has created renewed interest in zein as a high value co-product. Interest in biodegradable plastics and films has increased significantly due to environmental concerns. Industry estimates suggest a global demand for bioplastics approaching 1M metric tons by 2013 (2). Zein is a potentially attractive component of such products, due to its excellent film forming properties and ability to be melt processed. Previous research has shown that solution-cast films of zein and polyvinylpyrrolidone (PVP) form compatible blends (3). This was the first reported blend of zein with a synthetic polymer, and the resulting films showed modest improvements in tensile strength. Our current work has extended this research to include melt processed zein/PVP blends. In addition to PVP, we have also studied the effect of nanoclay on these melt processed blends. The nanoclay used in this study, Cloisite Na**+, is a natural montmorillonite clay commonly used as an additive to improve the physical properties of plastics. Cloisite Na**+ was specifically chosen because of its hydrophilicity, making it more likely than other nanoclays to effectively interact with the zein/PVP blends. The goal of this work was to achieve increased tensile strength/elongation of the zein/PVP blends by addition of up to 5% nanoclay. Samples were melt processed on a Brabender single screw extruder, then compression molded into tensile bars. For the zein/PVP blends, three different molecular weights of PVP were used between 2.5 and 20% by zein weight. Some zein/PVP blends showed a 10-15% increase in tensile strength for bars stored at 50% RH. All PVP/zein blends exhibit a single Tg by DSC. For zein samples blended with both PVP and nanoclay, the PVP and Cloisite Na**+ were used at concentrations from 1 to 5% by zein weight. Certain zein/PVP/Cloisite blends also showed a 10-15% increase in tensile strength, with the greatest increase for samples containing PVP10K with 5% Cloisite Na**+ . X-ray analysis suggests no intercalation between the zein and nanoclay under the conditions of single screw extrusion.