Mechanical recycling of PLA : Effect of weathering, extrusion cycles, and chain extender

Abstract This work evaluated the reprocessing of PLA with a high melt flow index (MFI). PLA samples were prepared by extrusion using a chain extender (Joncryl ADR‐4368) and subjected to two additional extrusion cycles with or without exposure to accelerated weathering. The results showed drastic affectations of PLA properties by weathering. The MFI increased from 65 to 137 g/10 min by reprocessing, while reprocessed and weathered samples reached a MFI of 417 g/10 min after three extrusion cycles. The addition of Joncryl prevented PLA degradation (MFI of 170 g/10 min after three extrusion cycles, even when weathering was performed). Additionally, the tensile strengths of weathered samples were substantially decreased (67%) compared to only reprocessed samples (14%). In this sense, PLA mechanical recycling is a good alternative if it is not exposed to harsh weathering conditions, in which case a chain extender is needed to get reasonable properties. Otherwise, reprocessing accelerated the composting of PLA, and the chain extender addition did not limit it.