The Studies Of Dynamic Rheological Behavior Of Polyethylene, Polypropylene And Their Color Masterbatches

In this article the dynamic rheological behavior of polyethylene, polypropylene and their color masterbatches was studied. The main conclusions were listed as followings.1.The concept of dynamic viscosity-temperature relationship of polymer melt was firstly proposed. The studies of the static and dynamic viscosity-temperature relationship of polyethylene and polypropylene showed that it was in accordance with the Arrhenius equation. The temperature-dependent behavior of frnaginaiy viscosity was more pronounced compared with that of real viscosity.2.The lower the molecular weight was, the higher the static and dynamic flowing activation energy was. The higher the frequency was, the lower the static and dynamic flowing activation energy was.3.It was found that the dynamic flowing activation energy was less than the static flowing activation energy The higher the molecular weight was, the bigger the difference between the dynamic and static flowing activation energy was.4.Anomalous dynamic viscosity-temperature relationship of LDPE and HDPE under dynamic stress field was found. The higher the frequency was, the higher the temperature corresponding to the anomalous viscosity-temperature relationship was. It was attributed to the existence or formation of order structure of PE melt under dynamic temperature sweep and dynamic stress sweep.III5.The dynamic rheological behavior of commercial polyethylene white color masterbatches was studiecL Their viscosity decreased with the increase of stress and the decrease of viscosity was related to the stress step.6.The time-dependent rheological behavior of commercial polyethylene color masterbatches was observed~ The time-dependent behavior of imaginaiy viscosity was more pronounced compared with that of real viscosity It was related to the formation of bard shell around the sample which impeded the further deformation of melt; resulting hi the increase of viscosity. It was also found that the higher the temperature and frequency were, the more pronounced the viscosity increase with time was. The temperature 2000C and 30wt0/o TiC)2 content were critical to the pronounced viscosity increase with time.7.For color masterbatches, there was large difference between their flowing ability and deformation ability. Here we firstly proposed that the flowing ability was characterized by MFR(melt flow rate) and their deformation ability was characterized by dynamic viscosity.8.The sttxlies of commercial h~jection PP color niasterbatches showed that for good dispersion of color masterbatches in the canier resins the rheological properties of color masterbatchos were superior to that of resins being colored. The PP color masterbatches whose MFR (test condition, 2000C, 2.16Kg) were more than five times of that of resins being colored and whose dynamic viscosity (test condition, 200 C, lOOrad/s)was less than 1/3 of that of resins were critical for good dispersion.