Fracture mechanisms of additively manufactured polylactide: Effect of in vitro hydrolytic degradation

This is the first study considering the effect of in vitro hydrolytic degradation at 37 °C on fracture mechanism of the most important aspect of additive manufacturing – the interface between layers. Specimens were tested transversely (failure between layers) and longitudinally (failure directly through extruded filaments) under testing conditions similar to those in the human body (submerged at 37 °C). Feature of fracture surface, including striations and localised ductility, significantly changed when degradation caused a reduction in molecular weight below 40 kDa from the initial 240 kDa or an increase in crystallinity above 12%. Such changes indicated a transition from more ductile to more brittle fracture during degradation.