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Supported single site catalyst and ethylene polymerizatlon

Author: SongLiXin
Tutor: WangQi
School: Zhejiang University
Course: Polymer Chemistry and Physics
Keywords: Olefins Ethylene polymerization Supported Single-center Montmorillonite Metallocene catalyst Alumoxane Polyethylene chain Nanocomposites An olefin polymerization catalyst
CLC: O643.3
Type: Master's thesis
Year: 2002
Downloads: 110
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Abstract


In recent years, the metallocene catalyst caused widespread concern in the industry and academia. Supported olefin polymerization catalyst even after years of extensive research, is still the coordination polymerization focus of research in the field, with a wide range of applications and academic value. In this thesis, supported aluminoxane Synthesis and Catalysis activity. Tried to use different methods in different pore size of the silica gel surface ethyl - mixed isobutyl alumoxane, was prepared with the supported alumoxane and the metallocene catalyst to catalyze the polymerization of ethylene. The relationship between research Catalyst and morphology of the polymer. The studies show that SiO 2 the H 2 O premix, adding AlR 3 of the method of preparation of the load type aluminum alumoxane can be prepared by the diameter 0-3.2mm between the ball-type polyethylene particles. This paper also studied montmorillonite as a carrier supported metallocene catalysts were synthesized, and in situ catalytic polymerization of ethylene to prepare a polyethylene / montmorillonite nanocomposites. Metallocene catalyst supported on montmorillonite interlayer impact on the the montmorillonite structure of the load reaction type, the process of change of the montmorillonite and polyethylene structure in the polymerization of different periods. Studies show that, by appropriate reaction of the metallocene catalyst can be fixed in the interlayer of montmorillonite, the catalytic polymerization of ethylene and interpolation layer polymer is formed. Only when the polymerization activity was higher before they can form a polyethylene / montmorillonite exfoliated nanocomposites. Olefin polymerization process for the the montmorillonite in situ load, we found that the polymerization reaction is carried out through three distinct stages: (1) The initial stage of polymerization, the monomer diffuses into the montmorillonite interlayer occurs at the active center of polymerization: polymerization (2) a relatively slow rate within the polyethylene chain in a two-dimensional plane interlayer growth, crystallization, and the formation of low melting point polymer. Montmorillonite interlayer distance increased in this process; (3) Finally, in the growth and crystallization of the polyethylene chain power drive, the layers of montmorillonite are completely softened, the polymerization rate has been greatly improved, resulting in higher melting point of the polyethylene, the same as the melting point of polyethylene with a homogeneous catalyst preparation. The above process showed that the catalyst polymerization was carried out in the restricted space within aggregation state and the structure of the polymer has a significant influence on the polymerization kinetics. Especially after the transition metal iron catalyst by the load, the melting point of the polymer has improved significantly. One of the reasons need to be further clarified.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic
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