PLA plasticized with low molecular weight polyesters: structural, thermal and biodegradability features

Poly(lactic acid) (PLA) was plasticized with ester oligomers having different structure, molecular weight and carboxylic acid content (AN) as end-functionalities. In particular PLA oligomers and a low molecular weight polyester of adipic acid and 1,2-propane diol (an adipate-based derivative) were used and compared. Their plasticizing capability was tested and the final structural and thermal properties of PLA matrix were evaluated by correlating the different features to the chemical and physical characteristics of these additives. SEC, DSC, TGA, tensile tests, XRD, SEM results, even after annealing, were collected, the related data analysed and evaluated with reference to additive starting properties. All the oligoesters resulted able to generate flexible compounds, but PLA oligomers provided mixtures with reduced structural and thermal stability. Finally, the most performing blend was tested for biodegradability to definitely assess the material suitable for the final application (sustainable packaging).