Structure And Property Research Of Polyethylene And Its Performance Improvement

The structure and property of different HDPE5000BR samples(samples number 1-5,sample number of the inferior quality is sample 5^#)are characterized by GPC,IR,NMR,DSC,rheology method and fractional distillation.The results show that their molecular structures,which influence their processing theology,are rather different although their polymerization processes are the same.GPC results shows that Mw of the sample 5^# is obviously lower than other four samples,its MWD is narrower than other four samples.IR and NMR results show that its branching degree is obviously lower than other four samples.C¹³-NMR result shows that the sample five has lower crystallization degree and higher non-crystallization zone content.The samples 1-3 have higher crystallization degree and the sample 4# has medium crystallization degree.DSC curve shows that the melting point of the sample 5# is slightly higher.Fractional distillation result shows that the branching point of the sample 5^# is not as even as other four samples,which leads to higher processing tempterature.The polymerization parameters are adjusted according to the analysis and test result,so product quality is improved.Our work indicates the reason why the property of the sample 5^# is inferior to other samples is its lower molecular weight,narrower MWD,lower branching degree, uneven branching degree distribution,higher melting temperature.