Patent ID: 7989549

Claim:
A polymer composition, comprising: a) a low molecular weight polyethylene component, having a density of 0.940 to 0.978 g/cm 3 , a melt index (I 2 ) of >80 to about 1200 g/10 min, a molecular weight (M w ) from about 10,000 to 40,000 g/mole, a molecular weight distribution (M w /M n ) of less than 5, and a melt flow ratio (I 21 /I 2 ) of from about 10 to about 65; and co-crystallized with b) a high molecular weight polyethylene component, having a density of 0.920 to 0.935 g/cm 3 , a melt flow index (I 21 ) of from about 1.0 to about 5.0 grams per 10 minutes, a molecular weight (M w ) ranging from about 100,000 to about 600,000 g/mole, a molecular weight distribution (M w /M n ) of less than 8, and a melt flow ratio (I 21 /I 2 ) of from about 20 to about 65, wherein the polymer composition has a single peak in a lamellar thickness distribution curve and a pipe made from the polymer composition has a PENT value according to ASTM F1473 of greater than 9000 hours at 80° C. and 2.4 MPa and a rapid crack propagation (RCP)S4-value of −5 degrees C. or lower at 10 MPa, and wherein the polymer composition has a density measured according to ASTM D-1505 of 0.940 g/cm 3 or greater and a molecular weight ranging from 200,000 to 350,000 g/mol, a melt index (I 5 ) of from about 0.01 to about 2.0 g/10 m, a flow index (I 21 ) of from about 2 to about 50 g/10 m, a melt flow ratio (I 21 /I 5 ) of from about 10 to about 50, a molecular weight distribution (M w /M n ) ranging from about 18 to about 32, where I 5 is determined according to ASTM D-1238, Condition 190° C./5 kg and I 21 is determined according to ASTM D-1238, Condition 190° C./21.6 kg.