High performance polylactic acid/thermoplastic polyurethane blends with in‐situ fibrillated morphology

As an environment‐friendly polyester, polylactic acid (PLA) shows great potential market value. While it still faces some obstacles in large‐scale practical application due to its brittleness. In this work, a novel strategy to improve the toughness of polylactic acid is developed. By adjusting processing temperature during the melt‐blending process, thermoplastic polyurethane/poly (D‐lactic) acid/poly (L‐lactic) acid (TPU/PDLA/PLLA) ternary blends with different morphology are obtained. The experimental results show that the TPU in ternary blends formed a fibrillated micro‐morphology, and the interfacial compatibility between the components is improved when the processing temperature is adjusted to 200°C. Under the synergistic action of in‐situ fibrillated TPU and stereocomplex (SC) crystals, the toughness of the ternary blends is improved significantly without sacrificing its own tensile strength. The maximum value of tensile strength, elongation at break, and fracture work of ternary blends are 61.9 MPa, 23.5%, and 1038.9 kJ/m3, respectively. In addition, the melt strength of ternary blends was significantly improved, which is a benefit to their processing application.