HIGH DENSITY POLYETHYLENE MELT BLENDS FOR IMPROVED STRESS CRACK RESISTANCE IN PIPE.

摘要

The invention provides a polyethylene composition comprising a melt blend of (i) a bimodal high molecular weight high density polyethylene resin having a NCTL stress crack resistance of about 200 hours or greater, and (ii) a high density polyethylene resin selected from the group consisting of a homopolymer high density polyethylene resin, a copolymer high density polyethylene resin, and mixtures thereof, wherein the composition has a minimum NCTL stress crack resistance of 24 hours. In another embodiment, a polyethylene composition comprises a melt blend of the bimodal high molecular weight high density polyethylene resin and a linear low density polyethylene resin. The bimodal high molecular weight high density polyethylene resin can be a commodity film grade resin, the homopolymer and copolymer resins can be milk bottle grade and detergent bottle grade, respectively, and the linear low density polyethylene resin can be a film grade. The composition are especially useful for manufacture of profile and corrugated pipe and/or pipe fitting applications, and chemical waste applications including sanitary sewer or irrigation piping systems.