Ultra-high molecular weight polyethylene (UHMWPE) possesses many excellent properties, but poor processability. There are many ways to improve the processability of UHMWPE, but most of which will compromise its other outstanding properties. The effect of polyethylene glycol (PEG) and high-density polyethylene (HDPE) on the rheological and mechanical properties of UHMWPE were investigated in this paper, and the UHMWPE blends were prepared by twin screw extruder. The addition of PEG can remarkably improve the processability of UHMWPE, so the UHMWPE/PEG (100/4) blends can be steadily extruded from the capillary. In addition, the apparent shear viscosity, storage modulus, loss modulus and the complex viscosity decrease with the increasing amount of PEG. However, the mechanical properties of UHMWPE/PEG blends decrease as the PEG content increase. The incorporation of HDPE can further improve the processability of the UHMWPE/PEG blends and reduce its apparent shear viscosity, storage modulus, loss modulus and complex viscosity. Mechanical properties test reveals that the best ratio of UHMWPE/HDPE is 60/40. Compared with UHMWPE/PEG (100/4), the tensile strength, flexural strength, and flexural modulus of UHMWPE/HDPE/PEG (60/40/4) increase by 13.8%, 25.7%, and 32.5%, respectively.

The melt drawability including melt strength (MS) and stretching ratio (V) of the neat low-density polyethylene (LDPE) and the LDPE composites loaded with a nanometer zinc oxide (nano-ZnO) were measured using a melt spinning method in capillary extruding temperature varied from 160 to 200℃ and within capillary flow rate range from 9 to 36 mm/s. It was found that the stretching ratio of the neat LDPE and the LDPE/nano-ZnO composites reduced with an increase of capillary flow rate while the V added with in a rise of capillary temperature. The melt strength of the neat LDPE and the LDPE/nano-ZnO composites enlarged with raising capillary flow speed; the MS reduced with an addition of capillary temperature. In addition, the dependence of the MS of the composites on the capillary temperature approximately accorded the Arrhenius expression.