Super-tough polylactic acid blends via tunable dynamic vulcanization of polyurethanes with ultrahigh bio-based content

Polylactic acid (PLA), a biodegradable plastic derived from renewable resources, is commercially available but has been limited in application owing to its inherent brittleness. To address this, researchers explored a reactive blending strategy using polyurethane (PU) to enhance PLA toughness. This method is straightforward and effective, yet most PUs are derived from petroleum or containing low bio-based content. Herein, we developed a bio-based PU (BPU) with an ultrahigh bio-based content of 93.8%, using 1,3-polypropanediol (PO3G) and 1,5-pentane diisocyanate (PDI) with double bonds for dynamic vulcanization to toughen PLA. The toughness and tensile strength of the PLA/BPU blends were adjustable by modifying the BPU content. In particular, the toughness of the blends could reach 68.69 kJ/m2 by varying the amount of BPU. In addition, the BPU20-0.1 sample demonstrated an optimal balance of stiffness and toughness, exhibiting a tensile strength of 47.8 MPa and a notched impact strength of 54.86 kJ/m2. This research broadens the scope for toughening PLA using BPUs, thereby diminishing the dependency on petrochemical resources.