The influence of self-crosslinked epoxidized castor oil on the properties of Poly (lactic acid) via dynamic vulcanization: Toughening effect, thermal properties and structures

In this work, the epoxidized castor oil (ECO) with self-crosslinking structure is prepared and a series of PLA/ECO blends are fabricated via dynamic vulcanization. The effects of raw castor oil and ECO with different contents on the static and dynamic mechanical properties, rheological properties, crystalline properties were studied. FTIR NMR and GPC results indicate the generation of self-crosslinking structure and the interaction between the oil and PLA matrix. DSC and TGA results show a higher crystallinity and lower thermal stability for PLA/ECO blends. It is also shown the better rheological and dynamic mechanical properties are obtained in PLA/ECO blends in comparison with raw castor oil filled samples. The data of static mechanical properties exhibit that ECO leads a much better toughening effect than that of the raw castor oil, which is also proved by the morphology photos of SEM, showing a better dispersion and smaller droplet size of oil, as well as the toughening mechanism of shear yielding and internal cavitation in PLA. However, the structures are defected in PLA matrix with the ECO contents over 10 wt% due to the agglomeration of ECO in local areas, leading significant decrease in mechanical properties.