Ultra-high toughness and strength polylactic acid/bio-polyamide 11 blend induced by dendritic structure of hyperbranched polyester with microcrystalline cellulose as the core

The development and use of bio-based materials instead of traditional petroleum-based materials is an effective way to conserve fossil resources and reduce carbon emissions. Polylactic acid (PLA) has considerable potential as a bio-based material for industrial purposes. However, its limited toughness restricts its widespread application. In this study, a hyperbranched polyester with microcrystalline cellulose as the core (MCC-EHBP) was designed, synthesized, and used to upgrade the compatibility of a PLA/bio-based polyamide 11 (PA11) blend by synchronously enhancing the toughness and strength of PLA. Owing to the excellent reactivity of the epoxy group, MCC-EHBP forms a block-like dendritic polymer structure with the molecular chain of PLA/PA11, which observably improves the compatibility of the two phases of the blend. The prepared PLA/PA11/MCC-EHBP blend has tensile strength of 67.37 MPa, impact strength of 38.75 kJ m^-2, and an elongation at break of 30.3 %, which are 36.9 %, 241.7 %, and 300.1 % higher than those of PLA, respectively. Moreover, the initial decomposition temperature and activation energy of PLA are increased by 5 °C and 17.3 %, respectively. The proposed simple, efficient, and environmentally friendly method for preparing PLA with ultra-high toughness, strength, and heat resistance is expected to broaden the industrial applications of this polyacid.