A New Strategy\nfor the Preparation of Fully Biobased\nand Biodegradable Polylactic Acid with Both High Rigidity and Flexibility

Tougheners are crucial for polylactic acid (PLA) because\nof its\ninherent brittleness. Among the many available tougheners, biobased\nand/or biodegradable tougheners are the primary choice. However, increasing\nPLA toughness typically leads to a trade-off with reduced rigidity\nor modulus. In this study, biobased and biodegradable thermoplastic\nvulcanizates (BBTPVs), made from PLA and a polyester elastomer (BBPE),\nare developed for toughening of PLA. The PLA phase in BBTPV ensures\nhigh compatibility with the PLA matrix, while the BBPE rubber phase,\nwith its adjustable cross-linking degree and particle size, allows\nfor controlled stress dissipation. Further, fully biobased and biodegradable\nPLA composites exhibiting excellent performances are prepared. The\nelongation at break and notched impact strength of the PLA–BBTPV\ncomposite increase by 31 and 12 times, respectively, compared with\npure PLA, while its tensile strength remains high (44.5 MPa). This\nstudy offers a new approach for preparing fully biobased and biodegradable\nPLA with high rigidity and flexibility.