Effect of clay on immiscible morphology of poly(butylene terephthalate)/polyethylene blend nanocomposites

Polymer blend nanocomposites containing poly(butylene terephthalate) (PBT), polyethylene (PE), and organoclay were prepared by direct melt compounding. Their immiscible morphologies weree investigated using electronmicroscopy, X‐ray diffraction, and parallel plate rheometry. The PE domain sizes were reduced when the polar PBT phase was continuous (PBT/PE = 60/40) because the clay tactoids effectively prevented the coalescence of the dispersed PE domains. However, when the PBT component presented domains dispersed in the rich PE matrix (PBT/PE = 40/60), the addition of clay (>2 wt %) changed the phase morphology into a novel cocontinuous one, which was further confirmed by rheological measurements. The existence of clay tactoids led to a sharp enhancement in the viscosity of the PBT phase, changing the viscosity ratio between the PBT and PE phases remarkably, which may have promoted the phase inversion. As a result, clay had significant effects on the morphology of the polymer blend.