Enhancing the flexural and impact properties of bioplastic poly(lactic acid) by melt blending with poly(butylene succinate)

Abstract

Bio-based biodegradable Poly(lactic acid) (PLA) suffers limitations such as brittleness and slow crystallization. This study aims to resolve the brittle nature of PLA by blending with Poly(butylene succinate) (PBS), a more ductile biodegradable polymer with superior toughness and flexural properties. In this research, a series of PLA/PBS blends was prepared at the blend ratios of 100/0, 80/20, 60/40, 40/60, 20/80 and 0/100. FTIR showed that there was no change in the functional groups of the PLA/PBS blends. Thermal stability assessed by TGA revealed that PBS degraded at higher temperature than that of PLA; the decomposition temperature (Td) at 10% weight loss of PLA and PBS were 330.8 and 356.4°C respectively. The Td of all the blends increased gradually with the addition of PBS. The flexural properties in terms of the flexural strength and the flexural modulus of the blends reduced significantly with PBS content. The PLA/PBS specimens with greater PBS content were softened and flexed more easily, thereby requiring a much lower flexural strength. The flexural modulus of the 80/20 and 60/40 blends dropped from 3.5 GPa for neat PLA to 3.2 GPa and 2.1 GPa while the flexural strength also declined from 105.3 MPa to 90.9 MPa and 69.1 MPa respectively. The toughness of all the blends was greater than that of neat PLA; in particular the 60/40 blend exhibited superior impact strength of 48.7 J/m compared with 30.9 J/m of the neat PLA. The microscopic images of all the blends showed two distinct phases; the 60/40 blend consisted of well dispersed small particles of the tough PBS, resulting in greater absorption of energy upon impact. © (2014) Trans Tech Publications, Switzerland.