THE EFFECT OF CATALYST ON COMPOSITION OF ETHYLENE/1-HEXENE COPOLYMERS DETERMINED BY MODIFIED FTIR METHOD 

Białek M., Sudoł M., Czaja K.

University of Opole, Institute of Chemistry

          Copolymerization of ethylene with 1-olefins is very important process using mainly to change properties of polyethylene. Incorporation of 1-olefin into polyethylene chain changes the structure, and consequently the properties of polymer product obtained. This effect is dependent on polymerization conditions, comonomer type and above all catalytic system [1]. Therefore, it has been interested to us to study the influence of catalyst on comonomer incorporation into polymer chain. In our studies we have investigated four catalysts supported on magnesium complex:

1.       MgCl₂(THF)₂/VCl₄/Et₂AlCl

2.       MgCl₂(THF)₂/VOCl₃/ Et₂AlCl

3.       MgCl₂(THF)₂/TiCl₄/ Et₂AlCl

4.       MgCl₂(THF)₂/Cp₂ZrCl₂/MAO

          The composition of ethylene/1-olefin copolymers is usually determined by IR or ¹³C-NMR methods. Because of very high molecular weight (low solubility) copolymers obtained over vanadium systems we could not have got their spectra then the incorporation of comonomer has been measured only by the modified FTIR method [2] using A₁₃₇₉/A₁₃₆₈ absorbance ratios, which had been obtained by the separation of analytical bands.

          It has been found that zirconocene and vanadium (VCl₄) catalysts preferentially incorporate 1-olefin into polyethylene chain in comparison to other Ziegler-Natta catalyst.

[1] Kaminsky W. in: Kricheldorf HR, editor. Handbook of Polymer Synthesis: part A, New York: Marcel Dekker, 1992

[2] Sudoł M., Czaja K., Białek M. Polimery 2000; 45, 405