Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2006
Publication Date: 6/5/2006
Citation: Sessa, D.J., Byars, J.A., Selling, G.W. 2006. Mechanical properties of films from zein reacted with glutaraldehyde [abstract]. Corn Utilization and Technology Conference. p. 43.
Technical Abstract: To improve the mechanical properties of zein films, zein was reacted in glacial acetic acid with varying amounts of glutaraldehyde (GDA) from 0.5 to 16% by weight based on weight of zein. When 0.5, 1, 2, 4 and 8% GDA were each added to zein solids dissolved in glacial acetic acid and allowed to cure in a close system at room temperature for one week, only did the zein reacted with either 4 or 8% GDA form a gel. Those gels were insoluble in organic solvents known to dissolve zein. Insoluble gel formation indicates that a cross linking reaction occurred at those GDA concentrations. Air dried films were generated from each of the reaction blends with GDA along with a zein control. Dynamic mechanical analysis (DMA) was performed on 8% GDA modified zein films with an ARES LS2 controlled strain rheometer equipped with a torsion rectangular fixture to measure the magnitude and temperature dependence of the complex G', G", and tan delta data sets where a primary Transition glass was observed at 172.5 deg C along with a second transition identified by a peak in G" at a temperature of 77.3 deg C. Differential scanning calorimetry (DSC) likewise yielded two transitions at temperatures similar to the DMA events which factor indicates that our films are biphasic. DSC of finely ground control film materials also gave two events. Physical testing of tensile bars cut from films and stored for one week at 50% RH was performed with an Instron where the specimens with a grip distance set at 50.00 mm were subjected to a cross-head speed of 10.00 mm/min. Evaluations of tensile bars from 0.5% GDA modified zein films showed minor enhancement of tensile strength, elongation %, and Young's modulus which increased and leveled off with 4% or greater GDA modifications. When the 4 to 16% GDA data are averaged for films reacted with GDA and compared with control films the tensile strength increased 2.9 fold (i.e. 44.8 MPa versus 15.5 MPa), elongation % increased 1.3 fold (i.e. 18.7% versus 14.2%), Young's modulus increased 2.5 fold (i.e. 448.2 MPa versus 179.4 MPa). GDA reaction with zein generated films with improved tensile strength, ductility and stiffness when compared with zein control films.