Preparation Of Polymer-Ligand Catalysts And Study On Catalytic Polymerization Of Ethylene

Polyolefin,which is one of most important synthetic polymeric materials in the world,has been widely applied in various fields,such as film,packaging,mechanical parts,electrical insulators,ink additives and hot melt adhesives.The preparation of polyolefins has been a hot spot for researchers to study because of its excellent properties(low cost,chemical inertness,mechanical properties,absence of potential toxicity,and processability).Different polyolefin materials can be obtained by different preparation methods and used in different fields.In this paper,we focus on improving the processing performance and mechanical properties of the materials.Through the design of the catalyst,the application of the catalyst based on polymer ligand is studied in the preparation of polyethylene.1)The well-defined nano-PS beads were prepared by emulsion polymerization,and then the aminated nanoparticles were prepared by modification.The different sizes of nanoparticles were prepared by exploring the different conditions,and the factors affecting the size of nanoparticles were studied.The results show that the radius distribution of the prepared nanoparticles is not related to the length of the nucleation time,mainly related to the rate of free radicals entering the latex particles,the reaction time,the amount of the initiator and the emulsifier.The factors of the functionanlization efficiency consists of the radius of the particles,reaction time and the dispersion of the particles.The smaller radius of the particles is,the content of functional groups in the carrier is higher.2)Different salicylaldehyde compounds were grafted by different condensation reactions.The grafted product structure was confirmed by various characterization methods,and the nanoparticle grafting product with good dispersion was obtained.The phenoxyimine structure was confirmed by 1HNMR,and indirectly demonstrated by FTIR and elemental analysis.The obtained product retains the morphology of the original nanoparticles more intact and is well dispersed as shown in the SEM images.3)The C1-C6 catalyst was prepared by loading.The effects of the amount of Al/Ti(Zr)on the catalytic activity of the supported catalysts were investigated.It is shows that the catalytic activity was the highest at 1000/1 to 1200/1.In addition,due to the different steric hindrance of the ligand,the central metal in the support becomes very different.The smaller the steric hindrance of the ligand is,the more the amount of central metal is.And when the central metal is the same one,the small steric resistance of the catalyst activity will be relatively higher.We have found that C1 is a Pressure-Sensitive FI Catalyst Supported by PS Nanoparticles.When other conditions keep the same,the higher the pressure is,the lower the molecular weight of PE is achieved.Using the molecular weight dependence of the pressure,we prepared bimodal PE by shifting from a low pressure of 2 bar to a higher pressure of 10 bar in one-pot.DSC data analysis shows that the second scan melting point is very different compared with the first scan.It implies that the PE forms low entanglement during polymerization process.The SEM micrographs of PE show that PE particles copy the morphology of PS support,and the approximate spherical PE particles were obtained.This means that the fragmentation behavior of PS nanoparticles support for FI catalyst follows a multi-grain mode.We found that the C4 did not have the same properties as C1.During the polymerization process,the fragmentation mechanism is also different,PE samples have a large number of PE fiber.But there are also some particles that copy the morphology of the catalyst.DSC data of PE is also very different compared with C1 catalytic polymerization.There is no low entanglement characteristics.