Nursing rallies to restore vetoed funds for nursing education

An examination of the precatalyst which contains three compounds (MgCl2–TiCl4‐aromatic ester) uncovered numberous properties that apparently are common to all precatalysts and have already been observed in the simpler systems: a continous decrease in the polymerization rate during polymerization, characterized by a deactivation index that does not depend on the precatalyst but only on the cocatalyst; isotacTiClty control by the [AI]/[aromatic ester] ratio in the cocatalytic solution; and fast and reversible control of kinetics and tacTiClty by the same ratio. The precatalyst prepared by impregnation of the aromatic ester in MgCl2 or MgCl2–TiCl4 presents moderate or no improvement when compared with the simpler MgCl2–TiCl4 catalysts. The yellow precatalyst prepared by milling MgCl2 with the aromatic ester and impregnating with TiCl4 are the only products that provide high activity and isotactic index above 95% simultaneously, as revealed by the patent literature. Interpretation of the role played by the electron donor, based on infrared studies, are proposed: in the precatalyst it controls fixation of TiCl4 on MgCl2; in the cocatalytic solution it regulates the isospecificity of the active site by contact with the alkylaluminium‐aromatic ester complex and slows polymerization. Free electron donor gradually poisons the active centers.

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Catalyseurs Ziegler‐Natta supportés sur MgCl₂ pour la polymérisation stéréorégulée du propène. III. Systèmes catalytiques à hautes performances comprenant un solide ternaire: MgCl₂, ester aromatique, TiCl₄

Spitz

Lacombe

Guyot

1984

J. Polym. Sci. Polym. Chem. Ed.

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Nursing rallies to restore vetoed funds for nursing education

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Catalyseurs Ziegler‐Natta supportés sur MgCl₂ pour la polymérisation stéréorégulée du propène. III. Systèmes catalytiques à hautes performances comprenant un solide ternaire: MgCl₂, ester aromatique, TiCl₄

Catalyseurs Ziegler‐Natta supportés sur MgCl₂ pour la polymérisation stéréorégulée du propène. III. Systèmes catalytiques à hautes performances comprenant un solide ternaire: MgCl₂, ester aromatique, TiCl₄

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Nursing rallies to restore vetoed funds for nursing education

Cited by 1 publication

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Catalyseurs Ziegler‐Natta supportés sur MgCl2 pour la polymérisation stéréorégulée du propène. III. Systèmes catalytiques à hautes performances comprenant un solide ternaire: MgCl2, ester aromatique, TiCl4

Catalyseurs Ziegler‐Natta supportés sur MgCl2 pour la polymérisation stéréorégulée du propène. III. Systèmes catalytiques à hautes performances comprenant un solide ternaire: MgCl2, ester aromatique, TiCl4

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Catalyseurs Ziegler‐Natta supportés sur MgCl₂ pour la polymérisation stéréorégulée du propène. III. Systèmes catalytiques à hautes performances comprenant un solide ternaire: MgCl₂, ester aromatique, TiCl₄

Catalyseurs Ziegler‐Natta supportés sur MgCl₂ pour la polymérisation stéréorégulée du propène. III. Systèmes catalytiques à hautes performances comprenant un solide ternaire: MgCl₂, ester aromatique, TiCl₄