Effect of Organically Modified Silicate Layers and the Mixing Sequence On Poly(Butylene Adipate-co-Terephthalate) and Poly(Lactic Acid) Blend's Morphology

This work investigates the mixing sequence of organically modified clay in the blend of poly (butylene adipate-co-terephthalate) (PBAT) and poly (lactic acid) (PLA) and its effect on the morphological and thermal properties of the blend. PBAT has high ultimate elongation but low modulus, while PLA is a rigid biodegradable polymer with relatively high modulus. An incompatible blend of these two polymers is not easily extrudable due to the phase separation encountered in the melt state. Addition of silicate layers to the blend overcomes this problem in addition to enhancing the mechanical properties of the resultant blend compared to that of the neat blends. Cloisite 30B, which consists of organically modified silicate layers known as organoclay, was melt-compounded with the aforementioned blend. In order to further investigate the interaction preference of the organically modified clays, mixing sequences were taken into consideration. The morphological changes were compared among the blends in which clay was first mixed with PBAT, PLA, or the blend. The morphology of the blends and clay dispersion were examined using Scanning Electron Microscopy (SEM), while the thermal stability of the blends were measured using Thermo-gravimetric Analyzer (TGA). The nano-composite blend showed a significant decrease in disperse phase domain size.