Effects of nanoclay and its localization on the morphology stabilization of PLA/PBAT blends under shear flow

Blends of an amorphous polylactide (PLA) with 25 wt% poly[(butylene adipate)-co-terephthalate] (PBAT) containing 1 and 5 wt% Cloisite 30B (C30B) nanoclay were prepared using an internal batch mixer. Three mixing strategies were used: (S1) direct mixing of all three components, (S2) mixing C30B and PLA followed by mixing with PBAT, and (S3) mixing C30B and PBAT followed by mixing with PLA. X-ray diffraction (XRD) and transmission and scanning electron microscopy (TEM and SEM) were used to study the C30B dispersion and the blend morphology. Small amplitude oscillatory shear (SAOS) and stress growth tests were also conducted to investigate the nanocomposites and blend rheological properties and morphological stability under shear flow. With 1 wt% C30B, the nanoparticles were located at the PLA-PBAT interface for all mixing routes, which was favorable for morphology stabilization. The average PBAT droplet-diameter was reduced from 1.30 mm for the neat PLA-PBAT blend to 0.75, 0.85, and 0.70 mm for blend nanocomposites depending on the mixing strategy used. Under shearing at 0.01 s(-1), droplet coalescence did not occur due to the presence of C30B at the interface of the polymer phases. On the other hand, in blends containing 5 wt% C30B, the location of the nanoparticles and the occurrence of coalescence depended on the mixing strategy used. (C) 2016 Elsevier Ltd. All rights reserved.