Cocontinuous phase morphology of asymmetric compositions of polypropylene/high‐density polyethylene blend by the addition of clay

A novel method of developing cocontinuous morphology in 75/25 and 80/20 w / w polypropylene/high density polyethylene (PP/HDPE) blends in the presence of small amount (0.5 phr) of organoclay has been reported. SEM study indicated a reduction in average domain sizes ( D ) of disperse HDPE when PP, HDPE, and the organoclay were melt‐blended simultaneously at 200°C. However, when the two‐sequential heating protocol was employed, (that is, the organoclay was first intercalated by HDPE chains at 150°C, followed by melt blending of PP at 200°C), very interestingly a cocontinuous morphology was found even for very asymmetric blend compositions. WAXD study revealed the intercalation of both PP and HDPE chains inside the clay galleries, when PP/HDPE and clay were melt‐mixed together at 200°C. However, when the two‐sequential heating protocol was used the organoclay platelets were selectively intercalated by the HDPE chains. Addition of SEPS in the blend decreased the D of HDPE domains in both the blending methods. Thus, the observed cocontinuous morphology in asymmetric composition of PP/HDPE blend in presence of clay is because of the barrier effect of the clay platelets in the HDPE phase that restrict the phase inversion into the domain/matrix morphology. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010