Preparation Of New Schiff Base Ligand Titanium Complex Catalyst And Polymerization Of Ethylene

The existing polyethylene catalysts can not effectively control the catalyst activity andmolecular weight of ethylene by changing the polymerization conditions in thepolymerization process. The synthesis of a new Schiff base titanium complex supportedcatalyst was studied in this paper.The new Schiff base aniline ligand was condensed by o-vanillin and3,5-dimethylaniline,and the effects of different reaction conditions on the yield of Schiff base wereinvestigated. With the extending of reaction time,the yield of ligand first increased andthen stabilized after four hours.With the increasing of reaction temperature,the yield ofligand first increased and then decreased a little,at50℃reached the maximum.The yieldof ligand was decreased in the wake of the enhancing of reactsnts and solvents.It was90.97%of the ligand yield in the optimal reaction condition.In addition,its structure wascharacterized by elemental analysis,nuclear magnetic resonace analysis and IR analysis toexplain the target structure of Schiff base was synthesized.It was indicated that schiff basehad good crystallinty and thermostability by DSC and XRD analysis.Titanium complex was prepared by titanium tetrachloride and Schiff base,and theeffects of different reaction conditions on the yield of titanium complex were investigated.With the extending of reaction time,the yield of titanium complex first increased and thendeclined after three hours a little.Titanium tetrachloride was added under lowtemperature(0℃) and the reaction yield reached the maximum at hightemperature(70℃).With the mole ratio of titanium tetrachloride and schiff base,theproportion was first increased and then decreased,the yield reached maximum when themole ratio was3:1.The titanium complex yield of70.12%in the optimal reaction conditionand we have got the target structure of titanium complex by elemental analysis and IRanalysis.The supported catalyst were prepared by modified montmorillonite which as the carrier and by changing the polymerization conditions to investigate the properties ofsupported catalyst in the process of polymerization.The results showed that by changingthe content of montmorillonite of the supported catalyst, aluminum titanium ratio,hydrogenpartial pressure,and content of titanium could control the activity of catalyst and themolrcular weight of polyethylene effectively.The montmorillonite with titanium complexeshas the ratio of100:1, aluminum with titanium has the ratio of200:1, hydrogen partialpressure was0,and the content of titanium was3.62×10-5mol were the best results,theactivity of catalyst reach to0.81×106gPE/(molTi4+·h),the molecular weight distribution ofpolyethylene reached1.6×106.XRD test showed that polyethylene had good crystallinity,DSC results declared that polymerization products were high density polyethylene,meltingtemperature were between134.26℃and135.92℃,Stratotype polyethylene particles couldbe seen in SEM images.