| 摘要 |
A polymerization catalyst system comprises at least one organometallic compound of the general formula MR1R1R11R111, in which M represents germanium, tin or lead, R1 represents an alkyl, aryl, aralky, or cycloalkyl group, and R11 and R111, each independently, represent an alkyl, aryl, aralkyl, or cycloalkyl group, a halogen radical, a nitrate or sulphate group, an alkoxy group, or a carboxyl group, and at least one tetravelent cerium compound. The system is preferably used to polymerize vinyl chloride alone, or in admixture with other monomers such as vinyl acetate, or acrylonitrile. The preferred organometallic compounds are (C4H9)4Sn, (CH3)4Pb, and (C2H5)4Pb. Specified cerium compounds are ceric nitrate, sulphate, iodate, and perchlorate, and ammonium ceric nitrate, sulphate, and pyrophosphate. The polymerization may be carried out at low temperatures, e.g. -60 DEG C., and in the presence of a solvent such as an alcohol, ether, or acetonitrile. Polyvinyl chloride obtained by using the catalyst has a syndiotactic structure.
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