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Study on Synthesis and Modification of Polypropylene with Different Tacticity

Author: WangWei
Tutor: WangLi
School: Zhejiang University
Course: Chemical processes
Keywords: Ziegler-Natta catalysts Low isotactic polypropylene Chlorinated polypropylene Polypropylene grafted
CLC: TQ325.14
Type: Master's thesis
Year: 2006
Downloads: 278
Quote: 2
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Isotactic polypropylene and low (LIPP) is a new kind of a polypropylene material, the kind of polypropylene in the industry mainly by the low load titanium mM MgCl 2 -supported Ziegler-Natta catalyst to catalyze the synthesis, but Currently, the catalytic activity of the catalyst is low, so how to improve the catalytic activity of the the low carrier titanium Ziegler-Natta catalysts are increasingly subject to the attention of academia and industry. In this paper, a kettle ball milling method (process I) Preparation of a new type of composite carrier MgCl 2 / AlCl 3 load ZN catalysts, the preparation process is simple, easy to operate, and the titanium content of controllability, stability, ease of engineering scale. A different AlCl 3 / MgCl 2 molar ratio catalysts for propylene polymerization, found that the AlCl 3 / the MgCl 2 < / sub> molar ratio of 0.12, and the catalyst containing an amount of 1.2wt% titanium, catalytic propylene polymerization activity reaches a maximum value with respect to MgCl 2 single carrier supported ZN catalyst, activity increased nearly doubled; polymerization kinetics and the use of the prepared catalysts for propylene polymerization relatively stable, suitable for industrial production. Preferably the polymerization conditions is found to [Ti] = 6.4 * 10 -6 gTi / ml, Al / Ti (mol / mol) = 40.T = 40 ℃, t = 30min, and in this condition The following can be low isotactic polypropylene. I the basis of the process, we have developed a kettle ball milling method to simplify the process (process II). Compared with the catalyst of the process I prepared in the case of titanium content of the same carrier, with the process II Preparation of composite carrier Aluminium from AlCl 3 / mM MgCl 2 supported ZN Catalyst The high activity of propylene polymerization, and the polymerization product isotacticity substantially constant; Process II method more simple and easy engineering scale, the resultant Catalyst propylene polymerization kinetics compared smooth, suitable for industrialized production. Preferably the polymerization conditions is found to [Ti] = 6.4 * 10 -6 gTi / ml, Al / Ti (mol / mol) = 40, T = 40 ℃, t = 30min, in this condition The following can be low isotactic polypropylene. Chemical reaction prepared MgCl 2 supported Ziegler-Natta catalyst, the catalytic activity of the resulting catalyst and catalytic propylene polymerization kinetics curve is relatively stable, suitable for industrial production. Preferably the polymerization conditions is found to [Ti] = 1.1 * 10 -5 gTi / ml, Al / Ti (mol / mol) = 80.T = 20 ℃, t = 30min, in this condition The following can be low isotactic polypropylene. Since the polypropylene non-polar polymer containing a polar group in the molecular chain, and thus the poor compatibility, adhesion, dyeability, and antistatic properties, which greatly limits the application of polypropylene, therefore polypropylene modified research is very necessary, graft modification and chloride modified is more commonly used and effective means of modified. The developed a swelling chlorinated new process, using this process, a particle size of not greater than 0.18mm of isotactic polypropylene particles more uniform chlorination of chlorinated polypropylene can be made by aqueous suspension chlorination: In order to enable diameter greater than 0.18mm isotactic polypropylene particles obtained in the aqueous suspension chlorination preferably chloride effect, we have developed a new process of a multi-stage swelling Chloride, using this process, capable of a particle size of 0.35 mm of isotactic polypropylene particles obtained by chlorination Chloride more uniform product. All resulting chlorinated product can be dissolved in carbon tetrachloride; all soluble in xylene at 80 ℃, after cooling, into a homogeneous transparent solution. In this paper, the two-step grafting reaction process to graft modification of the polypropylene fibers, to effectively reduce the formation of a homopolymer, has a good controllability of the reaction, the graft rate. Experimental results show that the preferred graft reaction conditions for the initiator decomposition temperature of 353K, the initiator concentration of 1.25% wt / v, graft reaction time 1h, the grafting reaction temperature of 353K, the graft monomer concentration of 1.09 mol / l. Meanwhile, we studied with a high-pressure liquid chromatography the graft reaction mechanism, and thus on the polyacrylic acid chain length of the grafted on the average number of grafting sites on the polypropylene, and each graft was calculated. The results show that in the above graft under the reaction conditions, an average of 914 propylene units a graft point, each of the grafting sites on the average graft chain length of the polyacrylic acid to 136 acrylic monomer.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > Polymer resin and plastic > Polyolefin plastic > Polypropylene
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