A comparative study of glycolic acid and L-lactic acid on modification of poly(butylene succinate)

A series of bio-based poly(butylene succinate-co-glycolate) (PBSGA) and poly(butylene succinate-co-lactate) (PBSLA) random copolymers with similar comonomer content were synthesized by the incorporation of glycolic acid (GA) or L-lactic acid (L-LA) into poly(butylene succinate) (PBS) macromolecular chains so as to provide ideal monomer for rapid degradation. The microstructure and composition of copolymers were investigated by using the proton nuclear magnetic resonance (1H NMR). Different scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM) techniques were used to further explore the thermal and crystallization properties. Although the introduction of comonomer weaken the crystallization ability of PBS, nucleation mechanism, crystal structure and crystal morphology did not change. In addition, shear rheological properties of PBS copolymers were preliminary investigated by rotary rheometer. PBSGA and PBSLA copolymers possessed splendid mechanical properties. Meanwhile, the degradation rate of copolymers was higher than PBS. Compared with PBSGA, the presence of side chain methyl in PBSLA weakens the crystallization properties and improves degradation rate. Besides, the composition, structure, thermal properties, crystallization and surface morphology of the copolymers were characterized by 1H NMR, DSC and scanning electron microscopy (SEM) during degradation process. In summary, the merge of L-LA or GA units not only enhances the hydrophilicity of the copolymers, but also improves the toughness and degradability without sacrificing mechanical properties.