Biobased and biodegradable ternary blends: Investigation of properties via experimental and theoretical routes

Biobased and biodegradable ternary blends from poly (lactic acid) (PLA), poly(3-hydroxybutyrate-co-hydroxy- valerate) (PHBV), and poly(propyiene carbonate) (PPC) were melt-compounded using a K-mixer and fabricated using an injection molding machine. The miscibility, degree of crystallinity, thermal stability, and mechanical properties were investigated. The blends were observed to be immiscible. PPC provided greater thermal stability in the blends compared to PHBV. The toughness and strain- At-break of the ternary blends were far superior to that of the binary blends due to the synergistic effect of the dispersed components. The stiffness and strength of the blends were consistent with those of the PLA matrix. The existing micromechanical models fit well for stiffness but underestimated the tensile strength. As such, a new empirical model was developed that took into consideration the flexibility that exists between the immiscible blends.