Thermoplastic blends of corn gluten meal/starch (CGM/Starch) and corn gluten meal/polyvinyl alcohol and corn gluten meal/poly (hydroxybutyrate-co-hydroxyvalerate) (CGM/PHB-V)

Corn gluten meal/starch (CGM/Starch), corn gluten meal/polyvinyl alcohol (CGM/PVAl), and corn gluten meal/poly (hydroxybutyrate-co-hydroxyvalerate) (CGM/PHB-V) blends were prepared in different proportions. Glycerol was used as plasticizer. The blends were prepared by melting in a Haake torque rheometer, followed by hot compression molding. The morphology of the blends containing CGM showed changes as a function of variations in blend composition. Water absorption at equilibrium did not vary to any significant extent in response to the addition of PVAl or Starch to CGM, and decreased with increasing PHB-V content. Tensile tests showed that the addition of PVAl increased the flexibility of the blends, while the presence of PHB-V enhanced their rigidity, but slight changes in mechanical properties were observed with the addition of Starch to CGM. The dynamic mechanical analysis (DMA) results revealed that all the blends exhibited two different glass transitions, one for each component, indicating that these blends are immiscible in the compositional range of this study.