Nanoclay Migration and the Rheological Response of PBAT/LDPE Blends

Blends of a poly(butylene adipate-co-terephthalate) (PBAT) and a low density polyethylene (LDPE) (80 wt%/20 wt%) were prepared through a twin screw extruder while incorporating 3 wt% Cloisite 30B (C30B) nanoclay that possessed a much higher affinity with PBAT. The blends were processed through three melt mixing strategies: (i) direct mixing of all three components, (ii) mixing C30B and PBAT followed by mixing with LDPE, and (iii) mixing C30B and LDPE followed by mixing with PBAT. The rheological properties of each system were determined in small amplitude oscillatory shear (SAOS) experiments. The migration of C30B nanoparticles from the LDPE minor phase towards the PBAT matrix was then monitored in the blend nanocomposites prepared through strategy (iii) via SAOS time sweep experiments. It was firstly understood that the C30B migration could be detected during time sweep SAOS experiments. The migration time was observed to be frequency dependent due to the smaller length scales probed at larger frequencies. Such migration occurred even faster when the SAOS time sweep experiments were conducted at a higher temperature due to the viscosity reduction.