Effects of thermal treatment and nucleating agents on crystallinity, toughness, and stiffness of PLA/PCL blends

The effects of the thermal treatment and nucleating agents on the morphology, crystallinity, and mechanical properties of poly(lactic acid)/poly(s-caprolactone) (PLA/PCL) blends were studied in order to obtain PLA/PCL blends with both high stiffness and toughness. The standard thermal treatment of the melt-mixed blends (a compression molding without annealing) resulted in the systems with optimized morphology (at PLA/PCL ratio 80/20) and very high toughness (ca 16· higher with respect to neat PLA), but the stiffness at elevated temperatures (above Tg of PLA at 65 °C) was low due to the low crystallinity of the PLA matrix (60 °C by ca two orders of magnitude. The achieved combination of the PLA/PCL toughness and stiffness was one of the highest, according to the available literature.