In‐reactor blends of ultra‐high molecular weight polyethylene (UHMW‐PE) and medium molecular weight polyethylene (mMW‐PE) were prepared by precise multi‐stage slurry polymerizations (MSP). Correlations between polymerization conditions and mechanical properties of in situ mixed polyolefins were investigated. Reactor powders were brought to shape through compression molding. Izod impact strength, dynamic mechanical analysis (DMA), and tensile properties, as well as physical properties (density, crystalline properties) were measured and evaluated in comparison with physical blends and commercial PE grades. In‐reactor blends show a higher material stiffness and impact properties increased by a factor of 2 compared to unimodal materials and physical blends. Thus the MSP‐method offers an efficient way to improve mechanical behavior of linear high‐molecular weight PE.
In‐reactor blends of ultra‐high molecular weight polyethylene (UHMW‐PE) and high‐density medium molecular weight polyethylene (mMW‐PE) were prepared by precise multi‐stage slurry polymerizations. Correlations between polymerization conditions and polymer properties of the reactor powders were investigated by means of scanning electron microscopy (SEM), bulk density and particle size analysis. It is shown that changing the polymerization conditions influences the particle surface morphology as well as the bulk density and this can make the dispersion of UHMW‐PE in mMW‐PE increase, as proposed in a model.
