Preparation Of Ultra-high Molecular Weight Polyprolene

Ultra-high Molecular Weight Polypropylene is a kind of thermoplastic engineering plastics,which viscosity-average molecular weight is more than one million,with high strength,high modulus,high wear resistance and strong antioxidant capacity.Due to the high molecular weight,the chain of ultra-high molecular weight polypropylene entanglement and contribute to a very high melt viscosity,poor mobility.It is very difficult to the processing the ultra-high molecular weight polypropylene by traditional processing and molding methods.At the same time,due to the chain transfer of propylene polymerization is uncontrollable.it's difficult to synthesis ultra-high molecular weight polypropylene by conven tional propylene polymerization.The problem of polymerization and processing is unsolved,the synthesis of ultra-high molecular weight polypropylene is upset,the industrial production of ultra-high molecular weight polypropylene is not available.However,with the development of 3D printing technology,the processing molding problem of ultra-high molecular weight polypropylene is expected to be solved in the future.Therefore,research of the synthesis of ultra-high molecular weight polypropylene has become a hotspot.The purpose of our work is to realize the production of ultra-high molecular weight polypropylene which molecular weight is more than 2 million by simulate the industrial production.We try to offer material for the test of 3D printing.We make preparation for further industrial production.We conduct the research about the influence factors of the molecule weight of polypropylene which including the main catalyst,cocatalyst and external donor on the molecular weight of polypropylene based on Ziegler-Natta(Z-N)catalyst.The molecular weight of polypropylene depend on the chain transfer.We try to combine the polymerization process and reaction conditions from the polymerization pressure,polymerization temperature,solvent and other aspects of its impact on the polymerization of propylene polymer ization chain transfer.The high efficiency catalyst system and polymerization process of ultra high molecular weight polypropylene were developed by the studying of the influencing factors of various propylene polymer chain transfer.Now,there is no effective method for the determination of the molecular weight of ultra-high molecular weight polypropylene.In this paper,the molecular weight of ultrahigh molecular weight polypropylene is determined by rheology and other methods.The research of influence factors to the molecular weight of the polymerized polypropylene product was conduct by using different kinds of external donor,cocatalyst,temperature and time in two batches of polymerization test.Polypropylene which viscosity average molecular weight is 2.04x106 g/mol was succeed producting.At the same time a series of production of polypropylene with viscosity average molecular weight range from 1 to 2 million was developed and the process parameters are adjustable at the same time.The molecular weight determination method of ultrahigh molecular weight polypropylene with viscosity,rheology and grading was established.