Synthesis Of [2-Ph-Ind]₂ZrCl₂ And Ethylene/1-hexene Copolymerization By The Metallocene Catalyst

Ethylene polymerization was studied with cycloalkylidene-bridged cyclopentadienyl titanocene catalyst (CH2)4C(Cp)2TiCl2 in the presence of methyl aluminoxane(MAO) as the cocatalyst. At 40℃ the catalyst reach its highest activity= 2.089×106 gPE/molTi-h while Mη=1.97×105 g/mol. Although at 60-80 ℃ the activity of this catalyst fall short of more than half of it at 40 ℃,which still keep at l×106 gPE/molTi·h of products and comparatively stabilize. Hence this cycloalkylidene-bridged cyclopentadienyl titanocene catalyst showes the higher activities at higher temperature which indicates it is very thermally stable and maybe a very promising catalyst system for industrial application.A series of metallocene complexes as CpZrCl3, Cp2TiCl2, Cp2ZrCl2 , (2-Ph-Ind)2ZrCl2 , CH2(Ind)2TiCl2 were synthesized according literature. Ethylene/1-hexene were copolymerized by (2-Ph-Ind)2ZrCl2/MAO in toluene at 0℃ and 50℃ respectively. A new activity-comonomer concentration relation was found in the copolymerization at 0℃. The polymerization activity underwent changes of increase-decrease with increase of hexane feed concentration. At 50℃, the polymerization activity goes down to zero sharply as 1 -hexene concentration is a little increased, meanwhile molecular weight distribution of polymer is widened and shows two peeks value. But adversely comparing with two temperatures at 0℃ and 50 ℃, the activity of ethylene homopolymerization at 50 ℃ is bigger more than four times as at 0℃. In this system comparing with at two solvents toluene and 1-hexene, the abnormal phenomena is that the 1 -hexene reactivity ratios rh is bigger at toluene thanthe other, while rE*m is also bigger and >1, which manifests blocks characteristic of ethane and 1 -hexene stereosequences.The comonomer content incorporated in polymer was determined by using 13C-NMR and IR. The comonomer content is proportioned to the feeding concentration. Thermal property of the ethylene/1-hexene copolymer was characterized by using stepwise segregation fractionation DSC. The lamella thichness is calculated. The short-chain branching(SCB) distribution is calculated by using both DSC method and NMR method. The difference between the two values is related to the homogeneity of comonomer in polymer: The NMR value is the true value of SCB, the less the difference is, the closer to true value the DSC value is; While DSC value is less than the NMR value, it could be concluded that relative more of comonomer existed in discrystallible successive segment or trend block copolymerization characteristic. This part of comonomer does not contributed to the decrease of melting temperature of polymer, but decreases the melting heat. While DSC value is greater than NMR value, most of comonomer existed in polymer chain in isolated state, and the length distribution of successive ethylene segment separated by comonomer unit is heterogeneous. This resulted in the polymer to show a relative low melting temperature but a relative high crystallinity. While DSC value is close to NMR value, the distribution of both comonomer in polymer and ethylene successive segment is homogeneous. The polymer has low melting temperature and low crystallinity. The weighted average melting temperature is defined. The weighted average melting temperature is proportional to the comonomer content in polymer. The slope of the relation could be use to characterize the efficiency of comonomer to decrease of melting temperature. The greater the absolute value of the slope is, the higher the efficiency is.In this system of ethane/1-hexene copolymerization using unbridged metallcene (2-PhInd)2ZrCl2/MAO at toluene solvent, we compared the no- and under- in addition magnetic field. Under in addition magnetic field the activity and molecular weight of polymerization are increased very much, molecular weight distribution becomesnarrow, 1-hexene content in the polymer decreased. It is happened at 0℃, and has no sound changes at 50℃. Since the explicit structure of metallocene with its polymer production have the corresp...