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Polyolefins Journal، جلد ۱۱، شماره ۴، صفحات ۲۳۵-۲۴۲
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عنوان انگلیسی The influence of magnesium dichloride as support on molecular weights of the polyethylenes produced by Ziegler-Natta catalyst
چکیده انگلیسی مقاله The paper presents data on the effect exerted by magnesium dichloride in Ziegler-Natta catalysts on the activity and molecular weight of polyethylene (PE) produced by ethylene polymerization in the absence or presence of hydrogen. It was found that ethylene polymerization in the absence of hydrogen over titanium-magnesium catalysts (TMCs) with different ratio of titanium chloride and magnesium dichloride (Ti/Mg = 0.5 and 0.07), oxidation state of titanium (TiCl3 or TiCl4) and structural characteristics of the catalysts leads to the formation of PE with a close molecular weight. At the same time, PE obtained over a δ-TiCl3 catalyst has a much (threefold) higher molecular weight. The introduction of hydrogen during polymerization for decreasing the molecular weight of PE is accompanied by a sharp drop in activity of the δ-TiCl3 catalyst, in distinction to the highly active supported TMC containing 3 wt. % Ti. Data about the effect of hydrogen content during polymerization on the molecular weight of PE were used to calculate the ratio of rate constants for polymer chain transfer with hydrogen (KtrH) and polymer chain propagation reaction (Кр). This value was close for TMCs of different composition containing magnesium dichloride. In the case of δ-TiCl3, the KtrH/Кр value was approximately two times lower compared to TMCs.
کلیدواژه‌های انگلیسی مقاله Ziegler-Natta catalysts, magnesium dichloride, titanium-magnesium catalysts composition and structure, Ethylene polymerization, molecular weight characteristics of polyethylene
نویسندگان مقاله Tatiana B. Mikenas |
Boreskov Institute of Catalysis SB RAS, pr. Akademika Lavrentieva, 5, 630090 Novosibirsk, Russia

A. V. Sholma |
Boreskov Institute of Catalysis SB RAS, pr. Akademika Lavrentieva, 5, 630090 Novosibirsk, Russia

Vladimir A. Zakharov |
Boreskov Institute of Catalysis SB RAS, pr. Akademika Lavrentieva, 5, 630090 Novosibirsk, Russia

Mikhail Matsko |
Boreskov Institute of Catalysis SB RAS, pr. Akademika Lavrentieva, 5, 630090 Novosibirsk, Russia

نشانی اینترنتی http://poj.ippi.ac.ir/article_2072_45dd75fdaba5984052badba7b3014298.pdf
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