Accelerated aging of 18 years rejuvenated polylactide bottles by fast scanning calorimetry

Abstract

This study focuses on the accelerated physical aging kinetics of rejuvenated polylactide (PLA) that has previously been processed and stored during 18 years under ambient conditions. The finish of a conditioned PLA bottle is subjected to structural relaxation for times varying between 0.001 and 1000.0 min at 45°C, that is, 15°C below its calorimetric glass transition temperature. The recovery of in‐situ aged PLA is monitored by fast scanning calorimetry and it is observed that the thermodynamic equilibrium is reached within the experimental aging time. Moreover, the time evolution of the enthalpy of recovery finds consistency with results obtained for PLA granules which did not undergo additional processing neither prolonged storage nor service life conditions. Thus, it is deduced that both processing and storage do not induce major degradation reactions that could affect the aging kinetics. Therefore, the behavior of a structurally rejuvenated amorphous PLA is depicted through the one of an unaged PLA.