Effects of polyol plasticizers on morphological characteristics and performance of injection‐molded polylactide/thermoplastic starch blends

Abstract Thermoplastic starch (TPS)‐based blends have attracted increased attention as a substitute for imperishable and non‐renewable plastics in various applications including packaging due to price competitiveness and being environmentally benign. However, the plasticizer type and quantity used to prepare TPS affect both the processability and performance of the final blends. Herein, TPS materials plasticized with both single (glycerol, xylitol, and sorbitol) and mixed polyol plasticizers (glycerol/xylitol and glycerol/sorbitol) were prepared and then blended with polylactide with a PLA:TPS weight fraction of 60:40. The effects of polyol plasticizers on the morphology and performance of injection‐molded PLA/TPS blends were discussed. Melt flowability and elongation of the glycerol‐plasticized PLA/TPS blend were much higher than those of other blends. In contrast, the blends plasticized with xylitol or sorbitol showed augmented tensile strength and Young's modulus, improved thermal stability, and reduced starch retrogradation. The reduction of TPS phase size and narrower size distribution were observed for blends plasticized with a higher fraction of xylitol or sorbitol. Crystallinity and cold crystallization temperature of PLA in the blends increased with increasing xylitol or sorbitol fraction. The obtained PLA/TPS blends have great potential for manufacturing renewable and biodegradable injection‐molded articles with tunable properties by incorporating appropriate polyol plasticizers. Highlights Injection‐molded polylactide/thermoplastic starch (PLA/TPS) blends are prepared. Glycerol (G), xylitol (X), sorbitol (S), and their mixtures are used as plasticizers. Higher X or S fraction increases strength, modulus, and thermal stability of blends. Higher X or S fraction decreases TPS phase size and starch retrogradation in blends. Higher X or S fraction increases PLA's T cc and crystallinity in the blends.