4. Conclusions
Polyethers, PEG and PTHF, were introduced as electron donors
in titanium based Ziegler–Natta catalysts supported on -MgCl2.
The synthesis procedure for applying the polyethers as electron
donors in the catalysts was found to be a very important factor.
When PEG and TiCl4 were added at the same stage, a PEG/TiCl4
complex was formed, decreasing the activity of the catalyst. The
formation of this complex can be prevented or hindered by fixing
PEG on -MgCl2 prior to the addition of TiCl4. As for PTHF, it was
found to partially decompose to THF in contact with the -MgCl2
synthesized in this work. The decomposition of PTHF was attributed
to the Lewis acidic nature of the lateral surfaces in the -MgCl2
and to possible presence of organomagnesium compounds in the
-MgCl2. The catalysts prepared in this work showed good activity
and comonomer response in the polymerizations suggesting the
polyethers are potential electron donors for Ziegler–Natta catalysts.
Ack