Morphology development of PLAs with different stereo-regularities in ternary blend PBSA/PBS/PLA films

Abstract

ABSTRACT This study was to investigate the influence of incorporating poly(lactic acid) (PLA) with different stereo-regularities into poly(butylene succinate-co-adipate) (PBSA)/poly(butylene succinate) (PBS). The PBSA/PBS matrix phase was fixed at 70/30 wt%, whereas the PLA contents were varied from 10 to 30 wt%. Two grades of PLAs with different D-lactide contents of 4.0% (Hi-PLA) and 1.0% (Lo-PLA) were used. The developed microstructures and morphologies of dispersed PLA phases were purposed from DSC and WAXD studies. Basically, the presence of PLAs in ternary blends significantly enhanced the bubble stability during film blowing. According to the different chain backbones of PLA, Hi-PLA was completely melted during the extrusion process and coalescence led to a larger size of the dispersed phase. The biaxial deformation of dispersed Hi-PLA occurred in bubble inflation stages bringing to the layer-like morphology. Conversely, the cold crystallization occurred in Lo-PLA droplets which could not further deform during the bubble forming. The different reinforcing morphologies of these PLA minor phases were investigated and correlated with their mechanical properties of ternary blend films. A good balance of stiffness and toughness was achieved from ternary blend containing 10 wt% of Hi-PLA. Finally, the developed PBSA/PBS/PLA films can be suggested as a suitable packaging for environmental sustainability.