检索结果-南通市图书馆

STEREOCHEMICAL CONTROL IN PROPYLENE POLYMERIZATION CATALYZED BY UNBRIDGED METALLOCENE CATALYSTS

Chinese Journal of Polymer Science 2001年第4期19卷 407-413页

作者： Yin-bang Zhu Zhi-qiang Fan Tariq Yasin Lin-xian Feng Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027, China 浙江大学浙江杭州

Two unbridged metallocene catalysts, bis(2,4,7-trimethylindenyl)zirconium dichloride (met-I) and bis(2,4,6-trimethylindenyl)zirconium dichloride (met-II), which are different in the position of substituents on the six-membered ring of the indenyl ligands were synthesized. The effect of substituents in the two metallocenes on the propylene polymerization was studied in the presence of methylaluminoxane (MAO) and triisobutylaluminium (TIBA). From the analysis of microstructure determined by C-13-NMR, it was demonstrated that the polymers produced by met-II have higher [mmmm] isotactic sequences than that of met-I. Using a mechanism based on model statistical analysis, it was found that chain-end model was dominant for met-I. However, met-II obeys the concurrent two-sites model during polymerization, which can be attributed to the existence of 'racemic-like' conformer in its system.

关键词： unbridged metallocene propylene polymerization elastomeric polypropylene stereochemical mechanism

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

THE INFLUENCE OF SUBSTITUENTS IN METALLOCENE ON PROPYLENE POLYMERIZATION

引用

Chinese Journal of Polymer Science 1999年第5期17卷 477-481页

作者：封林先 Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China

Two new unbridged zirconocenes, bis(2.4,7-trimethyl indenyl)zirconium dichloride (Met-I) and bis(2-methyl-4,7-diethyl indenyl)zirconium dichloride (Met-II) were prepared in order to investigate the steric effects of substituents on the nature of the catalysts for the: polymerization of propylene. A mixture of methyl aluminoxane (MAO) and triisobutylaluminum [Al(iBu)(3)] was used as cocatalyst to activate these catalysts. The decrease in steric bulkiness of substituents at 4 and 7 positions of the indenyl ring resulted in an increase of both activity and molecular weight as well as the isotacticity.

关键词： polymerization unbridged zirconocenes elastomeric polypropylene homogeneous metallocenes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：