Tailoring polylactide toughness: Synergistic effect of D-isomer content and biaxial stretching on mesophase evolution and toughening mechanism
Year: 2025
Type: article
Abstract: This study investigates the synergistic effects of D-isomer content and biaxial stretching on the mechanical, thermal, and microstructural evolution of polylactide (PLA). Commercial PLA grades with 2%, 4%, and 12% D-isomer content were biaxially stretched up to 3.5×3.5 and characterized. Increasing D-isomer content reduced stereoregularity, entanglement density, and glass transition temperature, thereby lowering strength. Biaxial stretching induced a brittle-to-ductile transition, accompanied by formation of a locally ordered mesophase whose content and morphology depended strongly on both D-isomer content and stretch ratio. Notably, PLA with 2% D-isomer achieved 137% elongation at break at a 2×2 stretch ratio, with mesophase content reaching 40% at 3×3. In contrast, grades with higher D-isomer content required greater stretch ratios for lower maximum elongations (~80-84%). Analyses revealed that smaller spherical mesophase domains in low D-isomer PLA promote microfibril-rich crazes that stabilize crack propagation. A novel toughening mechanism is proposed: biaxial stretching converts entanglements into a spherulitic mesophase, which nucleates controlled, energy-dissipative crazing. This strategy provides a practical route for tailoring PLA performance for advanced applications.
Source: Materials Today Communications
Authors: Mei Li, Sijie Chen, Yaoyao Qiu, Jiading Lin
Language: English
Subfield: Biomaterials
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,830
Award: G8477578330
OpenAlex ID: W7115065384