Modeling Thermal, Mechanical, and Hydrolytic Degradation of PLA During Single‐Screw Extrusion

ABSTRACT Molecular weight decrease caused by thermal, hydrolytic, and mechanical degradation of PLA is a major concern during melt processing. Modeling and predicting degradation is essential to minimize material deterioration and material property changes. Current kinetic degradation models show potential to describe degradation, but they are limited to rheometry and focus on thermal and/or hydrolytic degradation only. There is no model yet that describes degradation during melt processing techniques such as injection molding or extrusion. The aim of this work is to establish a degradation model that predicts the molecular weight decrease of PLA throughout single‐screw extrusion. A combination of experimental extrusion data and numerical simulations is used to establish the model. Subsequently, the model is experimentally validated to check its predictive quality. The results show good similarity between predictions and measurements for multiple process variables. The maximum deviation between both was found to be 5%. Combining experimental data with numerical simulations allows us to describe the extrusion process in an equipment‐independent way, which is essential to use the model for different extruders or dies. Overall, minimizing degradation during processing will avoid the loss of valuable resources, materials, and time, and will result in obtaining high quality products.