Effect of comonomer sequence distribution of LLDPE on miscibility of HDPE/LLDPE blends in the melt state

Two types of Linear low density polyethylenes (LLDPE) with different comonomer sequence distributions were blended with high density polyethylene, and the effect of the distribution on the miscibility behavior in the melt state was studied. Phase diagrams were constructed based on thermal behavior of the blends quenched from the melt. LLDPE prepared with Ziegler-Natta catalyst, which had more uneven comonomer distribution, was found to be more miscible with lower upper critical solution temperature compared to LLDPE prepared with metallocene catalyst. Rheological behavior and morphology of the blends were also examined, and the results showed good agreement with the phase behavior determined by thermal analysis.