Abstract:

The PE-HD/POE blends were modified by crosslinking with BIPB as a peroxide crosslinking agent. The gel content of the crosslinked PE-HD/POE was analyzed， and the effect of crosslinking modification on the rheology and crystallization of PE-HD/POE blends were investigated by rotary rheometer and DSC. The tensile and impact properties were characterized， and impact fracture surfaces were observed by SEM. The results indicated that the crosslinking modification increased the complex viscosity of the blends and inhibited their crystallization， resulting in a decrease in crystallinity and thinner wafers. When 0.3 wt % of BIPB was added， the notched impact strength of the blends reached 61.1 kJ/m²， and their elongation at break exceeded 900 %. When the crosslinking degree was low， most of the molecular chains in the blends could move freely. The toughening mode was attributed to the low entanglement that produces large deformation to form a shear yield zone to offset the impact energy. With the improvement of crosslinking degree， the toughening mode was converted to the high entanglement that generated a large amount of small deformation to dissipate the impact energy at a high cross-linking degree， leading to a better toughening effect.

Key words: peroxide crosslinking, high-density polyethylene, ethylene-octene copolymer, toughening modification, section morphology