Linear low density polyethylene from ethylene as an o nly monomer was prepared by the combination catalyst system of Et(Ind) 2ZrCl 2 an d {2 [2 Me 4 Br C 6H 3NC(Me)] 2C 5H 3N}FeCl 2 activated with methy laluminoxane (...Linear low density polyethylene from ethylene as an o nly monomer was prepared by the combination catalyst system of Et(Ind) 2ZrCl 2 an d {2 [2 Me 4 Br C 6H 3NC(Me)] 2C 5H 3N}FeCl 2 activated with methy laluminoxane (MAO).The two catalysts were well matched in a single reactor and i t was observed that the “comonomer effect" appeared in the in situ copolymeriz ation of ethylene.The comonomer effect was some strongly influenced by the molar ratio of Al to (Fe+Zr) and the polymerization temperatures.At 60℃ and n(Al )/n(Fe+Zr)=2000,the maximum activity of the catalytic system(8 5×10\+6g/mo l·h) was 4\^25 times higher than that of homopolymerization of ethylene(2\^0×1 0\+6g/mol·h),and the value of n(Fe)/n(Zr) was 0 5.At n(Al)/n(F e+Zr)=1000,the maximum activity diminished.When polymerization temperatures incr eased,the maximum activity of the in situ copolymerization decreased and the co rresponding ratio of Fe to Zr also decayed.The copolymers made from this catalyt ic system had the characteristics of low melting point(from 132 34℃ to 70 97 ℃),low density(from 0 9467?g/cm\+3 to 0\^9283?g/cm\+3) and narrow molecular weight distribution(from 2\^29 to 1\^86).However,it’s no obvious influence of th e comonomer effect on the physical properties of the copolymers.展开更多
Branched polyethylene from ethylene as single monomer was prepared by the tandem catalyst system of {2-[2-Me C6H4 N（Me）]2C5H3N}FeCl2（1） and {2,6-[1-(2,6-Me2-4-Br-C6H4N（Me）]2C5H3N} FeCl2（2） activated with methy...Branched polyethylene from ethylene as single monomer was prepared by the tandem catalyst system of {2-[2-Me C6H4 N（Me）]2C5H3N}FeCl2（1） and {2,6-[1-(2,6-Me2-4-Br-C6H4N（Me）]2C5H3N} FeCl2（2） activated with methylaluminoxane （MAO） .The products of polymerization were characterized by DSC,GPC and （）13C-NMR.The results revealed that the copolymer produced by in situ copolymerization of ethylene was a mixture of branched polyethylene and α-olefin.The content of α-olefin in the mixture was increased with increasing the molar ratio of catalysts 1/2.The MWD paramelers of polyethylene and copolymer were 28\^6 and 7\^9, respectively.（）13C-NMR spectra showed that there were ethyl groups,butyl groups and long chain alkyl groups in the copolymer.The average degree of branching of such branched polyethylene was less than 5C/1000C.展开更多
A novel catalytic system to prepare branched polyethylene with single catalyst activated by two different co-catalysts is reported in this paper via the tandem catalysis,with ethylene as single monomer.Such catalytic ...A novel catalytic system to prepare branched polyethylene with single catalyst activated by two different co-catalysts is reported in this paper via the tandem catalysis,with ethylene as single monomer.Such catalytic system is composed of β-diketonate zirconium complexes,i.e.(acac)2ZrCl2(Ⅰ)and(dbm)2ZrCl2(Ⅱ)as catalyst precursors,diethylaluminium chloride(AlEt2Cl)as a co-catalyst for ethylene oligomerization and methylaluminoxane(MAO)as another one for the in situ copolymerization with ethylene.The oligomers obtained were mainly α-olefins,and the contents of them in weight were 76.84 for Ⅰ and 65.99 for Ⅱ,while the part being able to be copolymerized was 62.12 and 55.32 for Ⅰ and Ⅱ,respectively.The branched polyethylene via in situ copolymerization of ethylene was prepared by the tandem catalytic system Ⅰ/AlEt2Cl/MAO or Ⅱ/AlEt2Cl/MAO.13C NMR spectrum reveals that the resultant copolymer was branched polyethylene with total branches of 2.1/1000C,including ethyl group of 1.2/1000C,butyl group of 0.8/1000C and longer branches of 0.1/1000C.With increasing the molar ratio of AlEt2Cl to MAO,the melting temperature of the polymer obtained decreased from 133.7 to 116.7 ℃ for Ⅰ/AlEt2Cl/MAO and from 131.7 to 118.8 ℃ for Ⅱ/AlEt2Cl/MAO as well as the change of crystallinity.The catalytic activities for catalyst Ⅰ/AlEt2Cl/MAO and Ⅱ/AlEt2Cl/MAO were from 2.48×104 to 0.10×104 g PE/(mol Zr·h)and from 1.00×104 to 0.32×104 g PE/(mol Zr·h),respectively.The results indicate that the branched polyethylene can be obtained by such a catalytic system.展开更多
文摘Linear low density polyethylene from ethylene as an o nly monomer was prepared by the combination catalyst system of Et(Ind) 2ZrCl 2 an d {2 [2 Me 4 Br C 6H 3NC(Me)] 2C 5H 3N}FeCl 2 activated with methy laluminoxane (MAO).The two catalysts were well matched in a single reactor and i t was observed that the “comonomer effect" appeared in the in situ copolymeriz ation of ethylene.The comonomer effect was some strongly influenced by the molar ratio of Al to (Fe+Zr) and the polymerization temperatures.At 60℃ and n(Al )/n(Fe+Zr)=2000,the maximum activity of the catalytic system(8 5×10\+6g/mo l·h) was 4\^25 times higher than that of homopolymerization of ethylene(2\^0×1 0\+6g/mol·h),and the value of n(Fe)/n(Zr) was 0 5.At n(Al)/n(F e+Zr)=1000,the maximum activity diminished.When polymerization temperatures incr eased,the maximum activity of the in situ copolymerization decreased and the co rresponding ratio of Fe to Zr also decayed.The copolymers made from this catalyt ic system had the characteristics of low melting point(from 132 34℃ to 70 97 ℃),low density(from 0 9467?g/cm\+3 to 0\^9283?g/cm\+3) and narrow molecular weight distribution(from 2\^29 to 1\^86).However,it’s no obvious influence of th e comonomer effect on the physical properties of the copolymers.
文摘Branched polyethylene from ethylene as single monomer was prepared by the tandem catalyst system of {2-[2-Me C6H4 N（Me）]2C5H3N}FeCl2（1） and {2,6-[1-(2,6-Me2-4-Br-C6H4N（Me）]2C5H3N} FeCl2（2） activated with methylaluminoxane （MAO） .The products of polymerization were characterized by DSC,GPC and （）13C-NMR.The results revealed that the copolymer produced by in situ copolymerization of ethylene was a mixture of branched polyethylene and α-olefin.The content of α-olefin in the mixture was increased with increasing the molar ratio of catalysts 1/2.The MWD paramelers of polyethylene and copolymer were 28\^6 and 7\^9, respectively.（）13C-NMR spectra showed that there were ethyl groups,butyl groups and long chain alkyl groups in the copolymer.The average degree of branching of such branched polyethylene was less than 5C/1000C.
文摘A novel catalytic system to prepare branched polyethylene with single catalyst activated by two different co-catalysts is reported in this paper via the tandem catalysis,with ethylene as single monomer.Such catalytic system is composed of β-diketonate zirconium complexes,i.e.(acac)2ZrCl2(Ⅰ)and(dbm)2ZrCl2(Ⅱ)as catalyst precursors,diethylaluminium chloride(AlEt2Cl)as a co-catalyst for ethylene oligomerization and methylaluminoxane(MAO)as another one for the in situ copolymerization with ethylene.The oligomers obtained were mainly α-olefins,and the contents of them in weight were 76.84 for Ⅰ and 65.99 for Ⅱ,while the part being able to be copolymerized was 62.12 and 55.32 for Ⅰ and Ⅱ,respectively.The branched polyethylene via in situ copolymerization of ethylene was prepared by the tandem catalytic system Ⅰ/AlEt2Cl/MAO or Ⅱ/AlEt2Cl/MAO.13C NMR spectrum reveals that the resultant copolymer was branched polyethylene with total branches of 2.1/1000C,including ethyl group of 1.2/1000C,butyl group of 0.8/1000C and longer branches of 0.1/1000C.With increasing the molar ratio of AlEt2Cl to MAO,the melting temperature of the polymer obtained decreased from 133.7 to 116.7 ℃ for Ⅰ/AlEt2Cl/MAO and from 131.7 to 118.8 ℃ for Ⅱ/AlEt2Cl/MAO as well as the change of crystallinity.The catalytic activities for catalyst Ⅰ/AlEt2Cl/MAO and Ⅱ/AlEt2Cl/MAO were from 2.48×104 to 0.10×104 g PE/(mol Zr·h)and from 1.00×104 to 0.32×104 g PE/(mol Zr·h),respectively.The results indicate that the branched polyethylene can be obtained by such a catalytic system.
