Compatibilization of Poly (Lactic Acid)/Polycarbonate blends using triacetin-mediated interchange reactions

Abstract

There is a strong interest in the use of poly (lactic acid) PLA which is a renewable polymer for environmental sustainability. The aim of the paper is to improve the properties of PLA by blending with polycarbonate (PC) at various ratios using melt blending technique. The effects of two types of triacetin (TA) as compatibilizers and tetra butyl ammonium tetraphenylborate (TBATPB) as catalyst were investigated. Mechanical, thermal and morphological properties of the PLA/PC blends were examined. The addition of both triacetin (2022 type, 5 wt%) with catalyst (0.2 wt%) in 50PLA/50PC blends showed good improvement in modulus and elongation at break. The Young’s modulus, flexural modulus and elongation at break increased by 280MPa, 238MPa and 94% respectively compared to uncompatibilzed 50PLA/50PC blend. It was depicted that transesterification reaction can take place only in the presence of compatibilizers; however, the addition of the catalyst accelerates the reaction. Dynamic mechanical analysis revealed a new peak attributed to the glass transition temperature (Tg) of the PLA-PC copolymer at a temperature (~ 110 °C) higher than Tg of typical PLA and lower than the Tg of typical PC. It can be concluded that the addition of triacetin and catalyst results in the overall best mechanical properties, thereby confirming the synergistic action promoted the transesterification reaction between PLA and PC promoting the compatibility of the PLA/PC system.