Green composites from a bioplastic blend of poly(3-hyroxybutyrate- co-3-hydroxyvalerate) and carbon dioxide-derived poly(propylene carbonate) and filled with a corn ethanol-industry co-product

Abstract

Sustainable green composites were engineered from distillers' dried grains with solubles (DDGS), a co-product from the corn ethanol industry as a sustainable filler in bioplastic matrices made from a carbon dioxide-derived poly(propylene carbonate) (PPC) and poly(3-hyroxybutyrate-co-3-hydroxyvalerate) (PHBV) blend. The effect of water-washed DDGS (15 and 25 wt %) on the properties of injection-molded green composites from PHBV/PPC blends (60/40) and (40/60) and DDGS without and with peroxide (0.5 phr) has been investigated. From the results, it was noticed that the glass transition temperature (Tg) of the PHBV/PPC (60/40) bioplastic matrix increased by ∼9.6 °C by adding a peroxide cross-linking agent, indicating significant interaction (linkage) between PHBV and PPC polymers in this particular composition ratio, which was supported by SEM analysis as no phase separation was observed between PHBV and PPC. The tensile modulus of PHBV/PPC (60/40) and PHBV/PPC (40/60) blends with peroxide was improved by ∼40.7 and 1.5% after the addition of 25 wt % DDGS, respectively, due to its fibrous flaky structure. The % elongation values at break of the PHBV/PPC (60/40) blend matrices with and without peroxide were drastically improved by 18.5 and 90.7 folds, respectively, as compared to that of brittle pristine PHBV.