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Biocomposites of a biopolymer and the coproduct of corn bioethanol industry, dried distillers' grains with solubles (DDGS), were produced by reactive melt extrusion and injection molding. The biopolymer matrix was a blend of polyhydroxy(butyrate- co-valrerate), PHBV, and poly(butylene adipate- co-terphthalate), PBAT. The effect of compatibilizer, polymeric methylene diphenyl diisocyanate (PMDI), and corn oil lubricant was studied. The change in melt processing force suggested the occurrence of chemical reactions during the processing. This hypothesis was further investigated by infrared spectroscopy by which the formation of urethane and urea bonds between DDGS and polymeric matrix was approved. Dynamic mechanical analysis confirmed the occurrence of crosslinks at PBAT-PHBV interface showing that the tan δ curves for PBAT and PHBV of the matrix shifted slightly towards each other. Moreover, the calculated parameter of interaction, A, from tan δ curves admitted the stronger bond at the DDGS-matrix interface as a result of addition of PMDI compatibilizer. Also, scanning electron microscopy images revealed improved interfacial adhesion at the DDGS-matrix interface as well as PBAT-PHBV interface within the matrix itself. The obtained crosslinked interfaces resulted in improvement in the strength, modulus, and elongation-at-break of biocomposites. Moreover, a synergism of PMDI and corn oil effects led to a dramatic improvement in impact strength of this biocomposite system so that the respective value for the prepared DDGS biocomposite increased from 75 to 212 J/m with addition of 1 % of PMDI and 3 % of corn oil. [ABSTRACT FROM AUTHOR]

A novel concept of developing green composites with improved performance using co-injection molding technique has been established. Poly (butylene succinate) (PBS), poly (butylene adipate- co-terephtalate) (PBAT), and their blends were investigated as skin material. Composite core material was made from poly (3-hydroxybutyrate- co-hydroxyvalerate) (PHBV) and miscanthus. Co-injected samples with good surface finish were achieved at a skin/core volume ratio of 40/60 and mold temperature of 45 °C. Notched impact strength of 140 J/m, four times higher than that of neat core material and unnotched impact strength of almost 400 J/m with modulus of more than 1 GPa was achieved for the co-injection molded green composites. Good adhesion at the skin/core interface was observed under scanning electron microscopy. [ABSTRACT FROM AUTHOR]