| The thesis presents the study on the changes of the active center distribution (ACD) of DQ-1 type Ziegler-Natta catalyst with conditions in homopolymerization of 1-hexene and propylene, and gives a primitive investigation on the copolymerization of propylene and 1-hexene with the same catalyst.The influences of quenching conditions on acetyl chloride quenching method for determining the concentration of the active sites in polymerization of 1 -hexene were investigated. We found that side reactions were negligible when quenching time was less than 10 minutes between 0癈 and 50癈. That addition of THF does not enhance the content of carbonyl in the polymer also implies that the influences of side reactions on the quenching reaction are negligible.The influences of polymerization temperature, external donor, hydrogen regulation and type of cocatalyst on the ACD in 1-hexene polymerization were investigated. The ACD was determined using a method of deconvoluting the molecular weight distribution (MWD) curves by multiple Flory distribution functions. The polymerization rate and the active center concentration were also determined. The results suggest that raising temperature and hydrogen regulation can activate the active sites producing polymer with low molecular weight. While the active sites, which produce polymer with high molecular weight, can be activated by external donor. We found that triisobutyl aluminium (TEA )mainly activates the sites producing high molecular weight polymer, while triethyl aluminium (TEA) activates the sites producing low one. A higher value of active center concentration was observed in TEA catalytic system, and a lower value was observed in TBA catalytic system. When methylalumoxane (MAO) was added to these systems, the active center concentration was markedly increased, especially in mixtures with TBA and TEA. With the addition of external donor Ph2Si(OMe) 2, obvious decrease in active center concentration was observed.The influences of changing the composition of cocatalyst mixtures TEA/MAO, TBA/MAO and TEA/TBA/MAO on the active sites distribution in 1-hexene polymerization were also investigated. The results suggest that there exist complexinteraction among different cocatalysts. MAO can activate the centers that produce polymer with low molecular weight in mixed cocatalysts, which is similar to hydrogen regulation.The effects of different mixtures of cocatalysts on the active sites distribution in propylene polymerization were investigated. The results suggest that there exists complex interaction between cocatalysts and external donor. Changing the composition of cocatalyst mixtures can regulate the active sites distribution to a certain degree following a similar law as that of 1-hexene polymerization, but the extent of MWD regulation is relatively small. Possibly, this is caused by the difference of monomer and reaction conditions. In the presence of hydrogen, the regulation function of mixed cocatalysts become small. MAO can raise isotactic index of produced polypropylene in mixed cocatalysts.After having studied the property of ACD in copolymerization of propylene and 1-hexene by DQ-l/TBA based on temperature-rising elution fractionation (TREF) and MWD measurement of the copolymer, we found that there exists great difference in ability between hornopolymerization of propylene and 1 -hexene and copolymerization of propylene and 1 -hexene of all types of active sites in the catalyst. The active sites producing polymer with low molecular weight can catalyze hornopolymerization of propylene and random copolymerization of propylene and 1-hexene easily. The active sites producing polymer with high molecular weight are unstable and they can catalyze hornopolymerization of 1-hexene easily, but they catalyze block copolymerization of propylene and 1-hexene more easily than hornopolymerization of 1-hexene in the presence of propylene. The activity of copolymerization of propylene and 1-hexene is higher than that of hornopolymerization of propylene.The present resu...
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