Preparation and characterization of ternary blends composed of polylactide, poly(ɛ-caprolactone) and starch

By means of a melt blending method, a ternary blend composed of polylactide (PLA), poly(ɛ-caprolactone) (PCL) and starch was prepared to conquer the major shortcomings (brittle and high price) of PLA. By the addition of PCL, PLA was tuned from rigid to ductile but its tensile strength was also reduced. To overcome the poor compatibility between PLA70PCL30 and starch, the acrylic acid grafted PLA70PCL30 (PLA70PCL30-g-AA) was chosen as the alternative for the preparation of ternary blends. Owing to the formation of ester carbonyl groups, the PLA70PCL30-g-AA/starch blend gave a much better dispersion and homogeneity of starch in the PLA70PCL30-g-AA matrix, and consequently led to apparently better properties. In a soil environment, the PLA70PCL30/starch gave the better biodegradation than the PLA70PCL30-g-AA/starch but the difference was slight. Finally, the PLA70PCL30-g-AA/starch blend not only provided a plateau tensile strength at break up to 50 wt% starch but also provided more easily processing properties.