Submitted to: Industrial and Engineering Chemistry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2012
Publication Date: 7/11/2012
Citation: Sessa, D.J., Selling, G.W., Biswas, A. 2012. Compatibility of melt-processed zein blends with methylenediphenyl 4,4'-diisocyanate-thermal, mechanical and physical properties. Industrial and Engineering Chemistry Research. 51(27):9199-9203.
Interpretive Summary: The market for bioplastics is set to top one million tons in 2011 and will grow rapidly to double in size by 2015, according to the European Bioplastics Association. Zein, a protein co-product of the ethanol industry, has the potential for use in the bioplastics industry. Our current research demonstrates that we can achieve synthesis of plasticized zein products with mechanical properties similar to those derived from petroleum-based products by melt processing zein modified with a diisocyanate. Based on the thermal, mechanical and physical properties of the melt-processed reaction products of zein with a diisocyanate, we have generated a compatible reaction product that can be used as a bio-based building block for the construction of new polymer composites. This finding not only will benefit the farmer and corn ethanol producers but also the multi-billion dollar thermoplastics industries.
Technical Abstract: Corn zein was melt-processed with methylenediphenyl 4,4'-diisocyanate (MDI) using triethylamine (TEA) as catalyst. The objective is to construct a melt-processed, compatible blend of zein with MDI that can be used as a building block for generating bio-based thermoplastics. The impact of cross-linking zein with MDI was followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to monitor growth in molecular weight. Various techniques were used to evaluate changes in properties after reaction. These included: FTIR to observe absorption differences of the cross-linked product; differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) to monitor the impact of cross-linking on thermal events; light microscopy to define surface characteristics and cross-sectional break of tensile bars when they were evaluated for mechanical properties by the use of an Instron Universal Testing Machine. Our findings demonstarte that zein can be melt-processed with MDI to generate a cross-linked product with improved tensile strength and elongation % when compared to melt-processed controls.