Effect of Poly(Ethylene Glycol)‐Poly(d‐Lactide) Block Copolymers on the Microstructure and Performances of Poly(l‐Lactide)/Rubber Blends

ABSTRACT

In this article, poly(ethylene glycol)‐poly(

‐lactide) (PEG‐PDLA) block copolymers with different PEG chain lengths were synthesized and melt‐mixed with poly(‐lactide) (PLLA) and rubber nanoparticles. The role of PEG‐PDLA block copolymers in tailoring the microstructures and performances of PLLA/rubber blend were investigated in detail. It was found that high contents of stereocomplex (SC) crystals were generated in PLLA/rubber/PEG‐PDLA copolymer blends, which induced rubber nanoparticles to agglomerate and form network‐like structures. The size of rubber aggregates and continuity of rubber network‐like structures first increased and then declined significantly as the PEG chain length increased. Resultingly, the impact toughness of PLLA/rubber/PEG‐PDLA copolymer blends first remarkably increased to 74.1 kJ/m² and then decreased to 30.6 kJ/m². Meanwhile, the elongation at break increased with increasing PEG chain length and little loss of tensile strength happened, revealing good stiffness‐toughness balance performances of PLLA/rubber/PEG‐PDLA copolymer blends. Moreover, the matrix crystallization rate of PLLA/rubber/PEG‐PDLA copolymer blends could be greatly increased by increasing PEG chain length and the PLLA/rubber/PEG‐PDLA copolymer blends exhibited much higher Vicat softening temperatures than PLLA/rubber blend, which confirmed the excellent heat resistance of PLLA/rubber/PEG‐PDLA copolymer blends. These interesting findings suggested that PEG‐PDLA block copolymers were highly conducive to prepare PLLA materials with outstanding comprehensive performances.