Strain-induced structural evolution of Poly(l-lactide) and Poly(d-lactide) blends. (2nd September 2016)

• Record Type: Journal Article
• Authors: Stoclet, G.
• Is Part Of: Polymer. Volume 99(2016)
• Page Start: 231
• Page End: 239
• Publication Date: 2016-09-02
• Subjects: Stereocomplex -- Polylactide -- Structural evolution -- Crystalline morphology; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2016.07.019
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: This work focuses on the mechanical behavior and the associated structural evolution of Polylactides homopolymers blends, i.e. PLLA and PDLA blends, with the aim of determining the ability to form the sterecomplex crystalline form upon stretching. The investigations carried out on initially amorphous samples revealed that only the crystalline α′-form, i.e . the one encountered in the case of the homopolymers, can be induced upon stretching indicating that the stereocomplex form cannot be strain-induced. Semi-crystalline samples initially under the stereocomplex form were also studied. Besides it was evidenced that while the strain-induced α′ crystalline form is strongly oriented toward the tensile axis, the sterecomplex crystals are almost insensitive to the mechanical treatment as a result of the presence of hydrogen bonds. Finally a brittle behavior was observed in the case of initially semi-crystalline samples under the α-form. This brittleness is ascribed to a phase separation process between the L-PLA and D-PLA macromolecules during the crystallization which involves a lack of cohesion between the crystalline lamellas, particularly due to the absence of tie molecules. Graphical abstract: Highlights: Mechanical behavior and strain-induced structural evolution of PLLA-PDLA blends. No possibility to induce the stereocomplex form upon stretching. High cohesiveness of the stereocomplex crystals. Brittle behavior induced by the presence of α-form crystals. Crystallization induced phase separation.