Wheat Gluten Blends with a Macromolecular Cross-Linker for Improved Mechanical Properties and Reduced Water Absorption

Wheat gluten (WG) is reactively blended with a macromolecular cross-linker, polyethylene-alt- maleic anhydride (PEMA), to simultaneously improve strength, stiffness, strain, and reduce water absorption for the first time. FTIR illustrates the cross-linking reaction. An increase in T-g measured by DSC and a decrease in protein extractability measured by SE-HPLC demonstrates an increase in cross-linking as PEMA content increases. The modified WG is thermo-molded into solid bars and tested for flexural properties. The flexural testing results indicate that the maximum strain and stress of the modified WG can be improved by as much as 95% and 120%, respectively. Addition of PEMA to WG lowers the water absorption by as much as a factor of 4 at the same time as improving the mechanical properties. The results are consistent with a single phase, intermolecular, cross-linked morphology. The improvements attained make these blends approach the properties of polystyrene and aerospace grade epoxies.