Effect of PEO-PPO-PEO copolymer on the mechanical and thermal properties and morphological behavior of biodegradable poly (L-lactic acid) (PLLA) and poly (butylene succinate-co-L-lactate) (PBSL) blends

A blend of two biodegradable and semi-crystalline polymers, poly (L-lactic acid) (PLLA; 70wt%) and poly (butylene succinate-co-L-lactate) (PBSL; 30wt%), was prepared in the presence of various polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) triblock copolymer contents (0.5, 1, 2wt%). Mechanical, thermal properties, and Fourier transform infrared (FTIR) analysis of the blends were investigated. It was found that the addition of copolymer to PLLA/PBSL improved the fracture toughness of the blends as shown by mode I fracture energies. It was supported by morphological analysis where the brittle deformation behavior of PLLA changed to ductile deformation with the presence of elongated fibril structure in the blend with copolymer system. The glass transition temperature (T_g), melting temperature (T_m) of PLLA, and PBSL shift-closed together indicated that some compatibility exists in the blends. In short, PEO-PPO-PEO could be used as compatibilizer to improve the toughness and compatibility of the PLLA/PBSL blends.