Study On Preparation Syndiotactic Polypropylene By Metallocene Catalyst

In this thesis, Cs-symmetric syndiospecific metalloncene catalyst, (C₁₃H₆Ph₂CMePhC₅H₄)ZrCl₂, was synthezied and was used for preparing the syndiotactic polypropylene (sPP).The important role of the solvent during the course of preparation of catalyst complex was studied. It was found that the ether was much more suitable solvent for the preparation of catalyst than other solvents. By using this complex and the cocatalyst, methylalumoxane(MAO), syndiotactic polypropylene (sPP) with syndiotacticity index (SI) >80%, melt point 130℃was prepared in the condition of low pressure. The metallocene complex and sPP have been characterized by means of IR, 1H NMR, EI-MS spectra and DSC.The different conditions such as temperature, solvent and [Al]/[Zr] have a great influence upon the process of polymerization. Through the kinetic curves, it was showed that the intensity of the reaction could be controlled by decreasing the temperature of the polymerization reaction. The thermal behaviors included thermal stability and the double melting peak phenomena were studied based on the sPP. It was confirmed that sPP was quite stable in air and the double melting peak was related to the different crystal of sPP. Furthermore the nonisothermal and the isothermal crystallization were investigated by DSC. KEY WORDS:Syndiospecific, Polypropylene,Polymerization,Metallocene...