Characterization and ageing study of poly(lactic acid) films plasticized with oligomeric lactic acid

Poly(lactic acid) (PLA) was melt-blended with a bio-based oligomeric lactic acid (OLA) plasticizer at different concentrations between 15 wt% and 25 wt% in order to enhance PLA ductility and to get a fully biodegradable material with potential application in films manufacturing. OLA was an efficient plasticizer for PLA, as it caused a significant decrease on glass transition temperature (T-g) while improving considerably ductile properties. Only one T-g value was observed in all cases and no apparent phase separation was detected. Films obtained by compression moulding were stored during 3 months under ambient controlled conditions and thermal, mechanical, structural and oxygen barrier properties were studied in order to evaluate the stability of the PLA-OLA films over time. Blends with 20 and 25 wt% OLA remained stable and compatible with PLA within the ageing period. Besides, PLA-20 wt% OLA formulation was the only one which maintained its amorphous state with adequate thermal, mechanical and oxygen barrier properties for flexible films manufacturing. (C) 2012 Elsevier Ltd. All rights reserved.