On the Mechanical, Thermal, and Rheological Properties of Polyethylene/Ultra-High Molecular Weight Polypropylene Blends

The novel ultra-high molecular weight polypropylene (UHMWPP) as a dispersed component was melt blended with conventional high-density polyethylene (PE) and maleic anhydride grafted-polyethylene (mPE) in different proportions through a kneader. Ultra-high molecular weight polypropylene is a high-performance polymer material that has excellent mechanical properties and toughness compared to other polymers. Mechanical, thermal, and rheological properties were presented for various UHMWPP loadings, and correlations between mechanical and rheological properties were examined. Optimal comprehensive mechanical properties are achieved when the UHMWPP content reaches approximately 50 wt%, although the elongation properties do not match those of pure PE or mPE. However, it is worth noting that the elongation properties of these blends did not match those of PE or mPE. Particularly, for the PE/UHMWPP blends, a significant drop in tensile strength was observed as the UHMWPP content decreased (from 30.24 MPa for P50U50 to 13.12 MPa for P90U10). In contrast, the mPE/UHMWPP blends demonstrated only minimal changes in tensile strength (ranging from 29 MPa for mP50U50 to 24.64 MPa for mP90U10) as UHMWPP content varied. The storage modulus of the PE/UHMWPP blends increased drastically with the UHMWPP content due to the UHMWPP chain entanglements and rigidity. Additionally, we noted a substantial reduction in the melt index of the blend system when the UHMWPP content exceeded 10% by weight.