Study of the Properties of Plasticised Poly(Lactic Acid) with Poly(1,3-Butylene Adipate)

Poly(lactic acid) (PLA) is a biodegradable thermoplastic that can be produced from renewable resources, and so was considered as a major alternative to petroleum-based plastics for packaging applications. However, plasticisation of PLA was required in order to obtain films with sufficient flexibility. Poly(1, 3-butylene adipate) (PBA) was used as a novel plasticiser for PLA, and acetyltributyl citrate (ATBC) was used as the control. FTIR revealed that interaction took place between PLA and plasticiser. With an increasing plasticiser content, storage modulus and glass transition temperature decreased, but elongation at break increased. The elongation at break of PBA-plasticised PLA (PBA content 30 wt.%) could be above 600%, higher than that of ATBC-plasticised PLA (ATBC content 30 wt.%). Moreover, PBA was able to restrain thermally induced migration of plasticiser in plasticised PLA. It was also found that the migration rate of ATBC was directly proportional to the ATBC content in the blends. The rheology showed that the plasticiser could obviously decrease the shear viscosity and improve the fluidity of the blends. PBA was therefore recognised as a novel plasticiser for enhancing the properties of PLA. In particular, as a biodegradable polymer, PBA, when used as a plasticiser in PLA, can enhance migration resistance for its proper molecular weight. Moreover, the area of application of plasticised PLA is broadened.