Super toughening of the poly(l-lactide)/thermoplastic polyurethane blends by carbon nanotubes

Carbon nanotubes (CNTs) were introduced into the poly(L-lactide)/thermoplastic polyurethane (PLLA/TPU) blend to prepare the ternary nanocomposites. The results showed that CNTs selectively localized in the TPU phase, leading to a morphological change from the sea-island morphology to the quasi-cocontinuous morphology. The high content of the CNTs induced the formation of the percolated network structure. Consequently, super toughened PLLA/TPU/CNTs nanocomposites were prepared successfully. More apparent cavitation of the TPU phase and the intensified local plastic deformation of the PLLA matrix under the impact load were observed on the impact-fractured surface of the ternary nanocomposites. This was believed to be the main toughening mechanisms for the ternary nanocomposites. After being annealed, besides the morphological change of the nanocomposites, PLLA matrix also exhibited a large number of crystalline structures. Furthermore, the impact toughness of the ternary nanocomposites was enhanced further.