Influence of diethylzinc on ethylene polymerization using iron catalyst homogeneous and supported on clay

• Diethylzinc (DEZ) introduced in ethylene polymerizations at different concentrations.
• Iron based catalyst system both homogeneous and also supported on clay.
• DEZ decreased catalytic, molecular weight and polydispersion.
• DEZ increased melting temperature and crystallinity degree of polyethylene.
• Clay lamellae became exfoliated in the polyethylene matrix.

Diethylzinc (DEZ) was introduced in ethylene polymerizations using iron based catalyst system both homogeneous and also supported on clay. The aim was to evaluate the influence of this compound on catalytic activity as well as on crystalline structure and thermal properties of polyethylene. The results showed that using the homogeneous system, the compound DEZ slightly decreased the catalytic activity while increased melting temperature of the synthesized polyethylene as observed by DSC analysis. Besides, X-ray diffraction technique showed that the crystallographic peaks of polyethylene were shifted to higher angles probably due to the dilatation of the orthorhombic unit cell by chain branching. In the polymerizations employing the iron catalyst supported on clay, the addition of DEZ also promoted an increase of the melting temperature of the polyethylene, and a slight increase in the degree of crystallinity was also observed.

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