Industrial & Engineering Chemistry Research, Vol.58, No.5, 1914-1923, 2019
Coexistence of Transcrystallinity and Stereocomplex Crystals Induced by the Multilayered Assembly of Poly(L-lactide) and Poly(D-lactide): A Strategy for Achieving Balanced Mechanical Performances
The multilayer architecture consisting of alternating poly(L-lactide) (PLLA) and PLLA/poly(D-lactide) (PDLA) blend layers was fabricated through layer-multiplying coextrusion. With the multiplication of layers, the spherulites tended to disappear and the whole specimen exhibited a transition from isotropic to highly oriented crystalline morphology. Finally, a specific TC/SC alternating multilayer structure was created for the first time when the layer numbers reached 1024. Resulting from such unique structure, the tensile strength and elongation at break of the 1024-layer specimen were respectively increased by 17% and 1528%, in comparison to those of the conventional blend specimen containing the same content of PDLA (similar to 2.5 wt %). Besides, largely enhanced resistance to scratch destruction which is critically related to the mechanical strength and ductility was also achieved. Thus, this research opens up a new horizon for achieving balanced mechanical performances of polylactide by tailoring its crystalline structures.