Blends of ethylene 1-octene copolymer synthesized by Ziegler-Natta and metallocene catalysts. II. Rheology and morphological behaviors

Abstract

The rheological and morphological behaviors of commercially available three binary blends of ethylene 1-octene copolymer (EOC) regarding the melt index (MI), density and comonomer contents, one component made by the Ziegler-Natta and the other by the metallocene catalysts, were investigated to elucidate miscibility and phase behavior. Miscibility of the EOCs blend in a melt state was related to the value of the MI, density, and comonomer content. If the comonomer contents are similar, then the melt viscosity is weight average value, otherwise it is positively or negatively deviated. The microtomed surface prepared by two different cooling processes-one is fast cooling and the other is slow cooling-indicated that all the blends were not homogenous regardless the density, MI, and comonomer content. The Ziegler-Natta catalyzed EOCs exhibited bigger spherulitic diameter and larger ring space than those of the metallocene EOCs prepared by a cooling process. The blends consisting of similar MI showed banded spherulites with different diameter, whereas the blend consisting of different MI and density takes place of explicit phase separation and phase inversion at 1 : 1 blend composition. The melt rheology appeared to influence the mechanical and film properties in the solid state.

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