Development of PLA based multiphase bioblends with improved properties

Blends containing 75 wt% of an amorphous polylactide (PLA) with 25 wt% of a poly[(butylene succinate)-co-adipate] (PBSA) or a poly[(butylene adipate)-co-terphthalate] (PBAT) were separately prepared using an internal batch mixer. The thermal, rheological, and mechanical properties of these blends were characterized using dynamic scanning calorimetry (DSC), rheometry, and tensile testing, respectively. It was shown that the PBSA and PBAT’s crystallization rate is much faster compared to that in PLA which improves the strength of the blend systems. On the other hand, both PBAT and PBSA significantly improved the PLA’s facture toughness and changed the PLA’s brittle behavior to ductile feature. The viscoelastic and morphological properties of these two blends were also analyzed and compared. The Palierne model was used to analyze the linear viscoelastic responses of the blends and to determine the interfacial tension between the polymer components. Moreover, in order to stabilize the blends’ morphology under shear flow, nanoclay was applied in PLA-PBAT blends to be acted as a smart droplet coalescence barrier if being localized at the interface of PLA matrix and PBAT drops. In this context, various mixing routes were applied to control the clay’s localization during the processing. The results showed that despite the existence of droplet coalescence in the neat PLA-PBAT blends during shearing, the presence of nanoclay at the interface of these polymer phases inhibited the PBAT droplets’ coalescence under shear flow.