Compatibilization-like effect of reactive organoclay on the poly(l-lactide)/poly(butylene succinate) blends

The morphology of an incompatible polymer blend composed of poly(l-lactide) (PLLA) and poly(butylene succinate) (PBS) was examined by scanning and transmission electron microscopy, X-ray scattering, and X-ray photoelectron spectroscopy before and after the incorporation of an organoclay containing reactive functional groups, namely twice functionalized organoclay (TFC). TFC was prepared by treating Cloisite® 25A with (glycidoxypropyl)trimethoxy silane. When a small amount of TFC was incorporated into the PLLA/PBS blend, the clay layers became fully exfoliated and were located mainly in the PLLA phase. At the low clay content, the dispersed phase had an almost constant domain size comparing with the PLLA/PBS blend, which decreased sharply as the clay content was further increased. When the clay content became high, the clay layers were dispersed not only in the PLLA phase but also in the PBS phase with intercalated/exfoliated coexisting morphology. The reactive TFC was found to play an important role in the blend similar to the in situ reactive compatibilizer. The specific interaction between the TFC and the polymer matrix was quantified by the Flory-Huggins interaction parameter, B, which was determined by combining the melting point depression and the binary interaction model. The morphology of the PLLA/PBS/clay composites was analyzed by considering the interaction parameter.