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Investigation of Chain Microstructure of Polypropylene Polymerized by Ziegler–Natta Catalysts with Diester and Diether Compound as Internal Donor via Hydrogen Chain Transfer
journal contribution
posted on 2020-01-27, 16:33 authored by Xuemin Yin, Yawei Qin, Jin-Yong DongTwo series of polypropylene samples
(PP) were prepared with two
MgCl2/TiCl4-type catalysts with diisobutyl phthalate
and 9,9-bis(methoxymethyl)fluorine as internal donors (named as cat1
and cat2), respectively, at different hydrogen dosages. The results
show that the molecular weights and microstructures of polypropylene
were affected by the dosages of hydrogen, which acted as a chain transfer
agent in propylene polymerization. For the two catalysts, the molecular
weights of polypropylene had an exponential relationship with the
hydrogen dosages, to which the total defect contents and lamellar
thicknesses (Ln) however
showed a linear dependency, indicating that hydrogen exerted similar
effects on the above polypropylene properties. However, there were
differences in the linear relationships of mmmm contents
and the hydrogen dosages for the two catalysts. Moreover, the linear
relationship between the lamellar thickness (L1) of PP prepared with the two catalysts and hydrogen content
is also different. It was suggested that for different catalysts of
different internal donors the hydrogen chain transfer followed different
patterns in affecting polypropylene properties. Our results provide
guidelines to obtain special quality polypropylene by hydrogen chain
transfer.