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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Plant Polymer Research » Research » Publications at this Location » Publication #195247
Title: TENSILE PROPERTIES OF COMPOUNDED AND INJECTION MOLDED CORN GLUTEN MEAL

Author
item Lawton Jr, John

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2006
Publication Date: 9/18/2006
Citation: Lawton Jr, J.W. 2006. Tensile properties of compounded and injection molded corn gluten meal [abstract]. p.80.

Interpretive Summary:

Technical Abstract: Corn gluten meal (CGM), the co-product from corn wet milling, contains between 60 to 70% protein about 45% of which is zein. The remainder contains about 22% starch and the balance is fiber and lipid. Research was conducted using a Haaka torque rheometer to identify conditions needed to produce thermoplastic melts of CGM. Zein and starch are both in a granular state in CGM. Triethylene glycol (TEG) and decanoic acid (DA) proved to be effective in disrupting and melting the protein. For CGM, the effect of water on its melt was different depending on the plasticizer used. Better melts were obtained for dry CGM with TEG, whereas CGM containing about 7% water gave the best melts with DA. DA was used as the plasticizer for CGM in extrusion runs, as it is not as hygroscopic as TEG. CGM containing 7% moisture and 30% DA was compounded on a Leistritz twin screw extruder, at 90 deg C, 100 RPM, and a feed rate of 17 g/min. The extrudate was injection molded into tensile bars using a Cincinnati Milacron Act-75-B molder. Tensile strength of the bars after storage at RT and 50% RH was 10 MPa. SEM of the fractured tensile bars revealed that the CGM was still granular after processing. To improve the tensile strength of the CGM tensile bars, CGM containing 30% DA and 7% moisture was extruded under various conditions and the SEM of the resulting extrudates examined. Extrusion conditions of 90 deg C, 100 RPM, and 23 g/min showed optimum melting in the extrudate. These conditions were used to compound CGM and the resulting extrudate was injection molded into tensile bars. No improvement was seen in the tensile strength of the bars. SEMs of the fractured surface of the bars showed an uneven surface, indicating that melting of the compounded CGM was incomplete in the injection molder.