Copolymerization of ethylene/norbornene catalyzed by high temperature resistant metallocene catalyst
A high activity and high temperature resistant metallocene catalyst for high-temperature solution copolymerization of ethylene/norbornene was synthesized.The effects of reaction temperature,molar ratio of Al to Zr,metallocene catalyst and norbornene concentration on the activity of the catalyst system were studied.The ethylene-norborene copolymer was characterized and whose polymerization conditions were determined.The results show that the activity of the catalyst system is up to 6.7×106 g/(mol·h)and the catalyst life is longer than 30 min at 140℃.The optimum polymerization condition is as follows:the reaction temperature is 140℃,the concentration of metallocene catalyst is 6×10-5 mol/L,the ethylene pressure is 1 MPa,the molar ratio of Al to Zr is 250,the molar ratio of B to Zr is 1.1,and the reaction time is 30 min.Under the optimal conditions the insertion rate of norbornene in the polymer is as high as 34.44%(y),the density is about 0.98 g/cm3,andtg is 135.8℃.
metallocene catalystethylene-norbornene copolymersolution polymerizationrelative molecular mass distributionmelt flow rate
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