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Giampiero Morini - One of the best experts on this subject based on the ideXlab platform.
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influence of 1 3 Diethers on the stereospecificity of propene polymerization by supported ziegler natta catalysts a theoretical investigation on their adsorption on 110 and 100 lateral cuts of mgcl2 platelets
Macromolecules, 2000Co-Authors: Massimiliano Toto, Giampiero Morini, Gaetano Guerra, Paolo Corradini, Luigi CavalloAbstract:Energy calculations relative to the adsorption of several substituted 1,3-Diethers on the unsatured (100) and (110) lateral cuts of MgCl2 are presented. Independent of the particular approach used, coordination of the Diethers on the (110) cut is always preferred. The energy difference favoring the Diether coordination on the (110) cut depends on the substituents on carbon 2 of the 1,3-alkoxypropane skeleton. These calculated energy differences are able to rationalize the observed dependence on the chemical structure of the 1,3-Diethers of the stereoregulating ability for propene polymerization of MgCl2/TiCl4 catalytic systems. In fact, a semiquantitative relationship has been found in the assumption that xylene-soluble (essentially atactic) and -insoluble (essentially isotactic) fractions of polypropylene obtained by these catalytic systems are prevailingly produced by Ti catalytic species adsorbed on (100) and (110) cuts, respectively.
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propene polymerization with mgcl2 supported catalysts effects of using a Diether as external donor
Macromolecular Chemistry and Physics, 1997Co-Authors: John C. Chadwick, Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Olof SudmeijerAbstract:13C NMR analysis of poly(propylene) fractions of different tacticity, obtained using a catalyst system of type MgCl 2 /TiCl 4 /diisobutyl phthalate - AlEt 3 - Diether, has provided further evidence that the active species in this system are similar to those in which the ether is used as internal rather than external donor. Chain-end analysis of relatively low molecular weight polymer fractions indicated, for polymers of similar molecular weight, similar proportions of butyl-terminated chain-ends, indicative of chain transfer with hydrogen following regioirregular (2,1-) insertion. The relatively high hydrogen response of Diether-containing catalyst systems can therefore be largely ascribed to this phenomenon, irrespective of whether the Diether is used as internal or external donor. At relatively low hydrogen concentrations, chain transfer to hydrogen takes place predominantly after the occasional secondary insertion, while the additional presence of vinylidene chain-ends in certain xylene-soluble fractions indicates that chain transfer via β-H transfer takes place mainly after primary insertion.
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Propene polymerization with MgCl2‐supported catalysts: effects of using a Diether as external donor
Macromolecular Chemistry and Physics, 1997Co-Authors: John C. Chadwick, Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Olof SudmeijerAbstract:13C NMR analysis of poly(propylene) fractions of different tacticity, obtained using a catalyst system of type MgCl 2 /TiCl 4 /diisobutyl phthalate - AlEt 3 - Diether, has provided further evidence that the active species in this system are similar to those in which the ether is used as internal rather than external donor. Chain-end analysis of relatively low molecular weight polymer fractions indicated, for polymers of similar molecular weight, similar proportions of butyl-terminated chain-ends, indicative of chain transfer with hydrogen following regioirregular (2,1-) insertion. The relatively high hydrogen response of Diether-containing catalyst systems can therefore be largely ascribed to this phenomenon, irrespective of whether the Diether is used as internal or external donor. At relatively low hydrogen concentrations, chain transfer to hydrogen takes place predominantly after the occasional secondary insertion, while the additional presence of vinylidene chain-ends in certain xylene-soluble fractions indicates that chain transfer via β-H transfer takes place mainly after primary insertion.
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microstructure distribution of polypropylenes obtained in the presence of traditional phthalate silane and novel Diether donors a tool for understanding the role of electron donors in mgcl2 supported ziegler natta catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Microstructure Distribution of Polypropylenes Obtained in the Presence of Traditional Phthalate/Silane and Novel Diether Donors: A Tool for Understanding the Role of Electron Donors in MgCl2-Supported Ziegler-Natta Catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
Incoronata Tritto - One of the best experts on this subject based on the ideXlab platform.
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microstructure distribution of polypropylenes obtained in the presence of traditional phthalate silane and novel Diether donors a tool for understanding the role of electron donors in mgcl2 supported ziegler natta catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Microstructure Distribution of Polypropylenes Obtained in the Presence of Traditional Phthalate/Silane and Novel Diether Donors: A Tool for Understanding the Role of Electron Donors in MgCl2-Supported Ziegler-Natta Catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Polymerization Stereochemistry with Ziegler−Natta Catalysts Containing Dialkylpropane Diethers: A Tool for Understanding Internal/External Donor Relationships
Macromolecules, 1996Co-Authors: Maria Carmela Sacchi, Giampiero Morini, Fabrizio Forlini, Incoronata Tritto, Paolo Locatelli, Luciano Noristi, Enrico AlbizzatiAbstract:A study on a new generation of MgCl2-supported Ziegler−Natta catalysts, which contain dialkylpropane Diethers as internal donors and have the property of producing highly active and stereospecific catalysts without any external donor, has been performed. The behavior of three different Diethers (2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane) as internal donors is compared with the behavior of the same Diethers when they are used as external donors with a catalyst containing diisobutyl phthalate as internal donor. The results obtained show that the same isospecific centers are produced when the same Diether donor is present as an internal donor or replaces diisobutyl phthalate during polymerization when it is added as an external donor. The sum of the present results and of the previously obtained findings on traditional supported Ziegler−Natta catalysts has enabled us to reach some conclusions on the role and reciprocal behavior of in...
Enrico Albizzati - One of the best experts on this subject based on the ideXlab platform.
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propene polymerization with mgcl2 supported catalysts effects of using a Diether as external donor
Macromolecular Chemistry and Physics, 1997Co-Authors: John C. Chadwick, Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Olof SudmeijerAbstract:13C NMR analysis of poly(propylene) fractions of different tacticity, obtained using a catalyst system of type MgCl 2 /TiCl 4 /diisobutyl phthalate - AlEt 3 - Diether, has provided further evidence that the active species in this system are similar to those in which the ether is used as internal rather than external donor. Chain-end analysis of relatively low molecular weight polymer fractions indicated, for polymers of similar molecular weight, similar proportions of butyl-terminated chain-ends, indicative of chain transfer with hydrogen following regioirregular (2,1-) insertion. The relatively high hydrogen response of Diether-containing catalyst systems can therefore be largely ascribed to this phenomenon, irrespective of whether the Diether is used as internal or external donor. At relatively low hydrogen concentrations, chain transfer to hydrogen takes place predominantly after the occasional secondary insertion, while the additional presence of vinylidene chain-ends in certain xylene-soluble fractions indicates that chain transfer via β-H transfer takes place mainly after primary insertion.
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Propene polymerization with MgCl2‐supported catalysts: effects of using a Diether as external donor
Macromolecular Chemistry and Physics, 1997Co-Authors: John C. Chadwick, Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Olof SudmeijerAbstract:13C NMR analysis of poly(propylene) fractions of different tacticity, obtained using a catalyst system of type MgCl 2 /TiCl 4 /diisobutyl phthalate - AlEt 3 - Diether, has provided further evidence that the active species in this system are similar to those in which the ether is used as internal rather than external donor. Chain-end analysis of relatively low molecular weight polymer fractions indicated, for polymers of similar molecular weight, similar proportions of butyl-terminated chain-ends, indicative of chain transfer with hydrogen following regioirregular (2,1-) insertion. The relatively high hydrogen response of Diether-containing catalyst systems can therefore be largely ascribed to this phenomenon, irrespective of whether the Diether is used as internal or external donor. At relatively low hydrogen concentrations, chain transfer to hydrogen takes place predominantly after the occasional secondary insertion, while the additional presence of vinylidene chain-ends in certain xylene-soluble fractions indicates that chain transfer via β-H transfer takes place mainly after primary insertion.
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microstructure distribution of polypropylenes obtained in the presence of traditional phthalate silane and novel Diether donors a tool for understanding the role of electron donors in mgcl2 supported ziegler natta catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Microstructure Distribution of Polypropylenes Obtained in the Presence of Traditional Phthalate/Silane and Novel Diether Donors: A Tool for Understanding the Role of Electron Donors in MgCl2-Supported Ziegler-Natta Catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Polymerization Stereochemistry with Ziegler−Natta Catalysts Containing Dialkylpropane Diethers: A Tool for Understanding Internal/External Donor Relationships
Macromolecules, 1996Co-Authors: Maria Carmela Sacchi, Giampiero Morini, Fabrizio Forlini, Incoronata Tritto, Paolo Locatelli, Luciano Noristi, Enrico AlbizzatiAbstract:A study on a new generation of MgCl2-supported Ziegler−Natta catalysts, which contain dialkylpropane Diethers as internal donors and have the property of producing highly active and stereospecific catalysts without any external donor, has been performed. The behavior of three different Diethers (2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane) as internal donors is compared with the behavior of the same Diethers when they are used as external donors with a catalyst containing diisobutyl phthalate as internal donor. The results obtained show that the same isospecific centers are produced when the same Diether donor is present as an internal donor or replaces diisobutyl phthalate during polymerization when it is added as an external donor. The sum of the present results and of the previously obtained findings on traditional supported Ziegler−Natta catalysts has enabled us to reach some conclusions on the role and reciprocal behavior of in...
Maria Carmela Sacchi - One of the best experts on this subject based on the ideXlab platform.
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microstructure distribution of polypropylenes obtained in the presence of traditional phthalate silane and novel Diether donors a tool for understanding the role of electron donors in mgcl2 supported ziegler natta catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Microstructure Distribution of Polypropylenes Obtained in the Presence of Traditional Phthalate/Silane and Novel Diether Donors: A Tool for Understanding the Role of Electron Donors in MgCl2-Supported Ziegler-Natta Catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Polymerization Stereochemistry with Ziegler−Natta Catalysts Containing Dialkylpropane Diethers: A Tool for Understanding Internal/External Donor Relationships
Macromolecules, 1996Co-Authors: Maria Carmela Sacchi, Giampiero Morini, Fabrizio Forlini, Incoronata Tritto, Paolo Locatelli, Luciano Noristi, Enrico AlbizzatiAbstract:A study on a new generation of MgCl2-supported Ziegler−Natta catalysts, which contain dialkylpropane Diethers as internal donors and have the property of producing highly active and stereospecific catalysts without any external donor, has been performed. The behavior of three different Diethers (2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane) as internal donors is compared with the behavior of the same Diethers when they are used as external donors with a catalyst containing diisobutyl phthalate as internal donor. The results obtained show that the same isospecific centers are produced when the same Diether donor is present as an internal donor or replaces diisobutyl phthalate during polymerization when it is added as an external donor. The sum of the present results and of the previously obtained findings on traditional supported Ziegler−Natta catalysts has enabled us to reach some conclusions on the role and reciprocal behavior of in...
Fabrizio Forlini - One of the best experts on this subject based on the ideXlab platform.
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microstructure distribution of polypropylenes obtained in the presence of traditional phthalate silane and novel Diether donors a tool for understanding the role of electron donors in mgcl2 supported ziegler natta catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Microstructure Distribution of Polypropylenes Obtained in the Presence of Traditional Phthalate/Silane and Novel Diether Donors: A Tool for Understanding the Role of Electron Donors in MgCl2-Supported Ziegler-Natta Catalysts
Macromolecules, 1996Co-Authors: Giampiero Morini, Enrico Albizzati, Giulio Balbontin, Ines Mingozzi, Maria Carmela Sacchi, Fabrizio Forlini, Incoronata TrittoAbstract:Three Diethers, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane, differing in the bulkiness of the alkyl substituents in position 2, have been used as internal donors in MgCl2−TiCl4−Diether/AlR3 catalysts for the polymerization of propylene. The performance of the three Diether-based catalysts is compared with that of a “traditional” MgCl2-supported catalyst based on the phthalate/silane donor pair and with that of a “donor-free” catalyst by coupling the temperature rising elution fractionation (TREF) analysis with a study of the stereoregularity of the first monomeric unit insertion. On the basis of the experimental data obtained, the action mechanisms of the different donors are discussed taking into account the various models presented in the literature.
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Polymerization Stereochemistry with Ziegler−Natta Catalysts Containing Dialkylpropane Diethers: A Tool for Understanding Internal/External Donor Relationships
Macromolecules, 1996Co-Authors: Maria Carmela Sacchi, Giampiero Morini, Fabrizio Forlini, Incoronata Tritto, Paolo Locatelli, Luciano Noristi, Enrico AlbizzatiAbstract:A study on a new generation of MgCl2-supported Ziegler−Natta catalysts, which contain dialkylpropane Diethers as internal donors and have the property of producing highly active and stereospecific catalysts without any external donor, has been performed. The behavior of three different Diethers (2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, and 2-ethyl-2-butyl-1,3-dimethoxypropane) as internal donors is compared with the behavior of the same Diethers when they are used as external donors with a catalyst containing diisobutyl phthalate as internal donor. The results obtained show that the same isospecific centers are produced when the same Diether donor is present as an internal donor or replaces diisobutyl phthalate during polymerization when it is added as an external donor. The sum of the present results and of the previously obtained findings on traditional supported Ziegler−Natta catalysts has enabled us to reach some conclusions on the role and reciprocal behavior of in...