Tuning Biodegradation of Poly (lactic acid) (PLA) at Mild Temperature by Blending with Poly (butylene succinate-co-adipate) (PBSA) or Polycaprolactone (PCL)

Biobased plastics are fully or partially made from biological resources but are not necessarily biodegradable or compostable. Poly (lactic acid) (PLA), one of the most diffused bioplastics, is compostable in industrial environments, but improving degradation in home composting conditions, in soil and in seawater could be beneficial for improving its end of life and general degradability. Blends obtained by the extrusion of PLA with different amounts of poly (butylene succinate-co-adipate) (PBSA) or poly (caprolactone) (PCL) were characterized in terms of their home composting, soil, marine and freshwater biodegradation. The blending strategy was found to be successful in improving the home compostability and soil compostability of PLA. Thanks to the correlations with morphological characterization as determined by electron microscopy, it was possible to show that attaining an almost co-continuous phase distribution, depending on the composition and melt viscosity of the blend components, can enhance PLA degradation in home composting conditions. Tests in marine and freshwater were also performed, and the obtained results showed that in marine conditions, pure PLA is degradable. A comparison of different tests evidenced that salt dissolved in marine water plays an important role in favoring PLA's degradability.