Controlling Polyolefin Properties by In‐Reactor Blending: 3. Mechanical Properties

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. magnified image