Polyethylene composition having high mechanical properties and processability

A polyethylene composition comprising:

• A) from about 30 to about 70 wt. %, based on the total weight of the polyethylene composition, of an ethylene polymer, wherein the ethylene polymer is an ethylene homopolymer or copolymer having a density equal to or greater than about 0.960 g/cm3 and melt flow index MIE at 190° C. with a load of 2.16 kg, according to ISO 1133, of about 50 to 100 g/10 min.;
• B) from about 30 to about 70 wt. %, based on the total weight of the polyethylene composition, of a second ethylene polymer, wherein the second ethylene polymer is a copolymer having a MIE value lower than the MIE value of component A),
• wherein the polyethylene composition has:
• 1) a density from about 0.945 to about 0.951 g/cm3, determined according to ISO 1183 at 23° C.;
• 2) a ratio MIF/MIP from about 25 to about 43, where MIF is the melt flow index at 190° C. with a load of 21.60 kg, and MIP is the melt flow index at 190° C. with a load of 5 kg, both determined according to ISO 1133;
• 3) a MIF from about 3.5 to less than 8.5 g/10 min.;
• 4) a HMWcopo index from about 1 to about 40;
• 5) a long-chain branching index, LCBI, equal to or greater than about 0.83;
• wherein the HMWcopo index is determined according to the following formula:
• HMWcopo=(110.02×tmaxDSC)/(10{circumflex over ( )}5)
• where
• (i) η0.02 is the complex viscosity of a melt in Pa·s, measured at a temperature of 190° C., in a parallel-plate rheometer under dynamic oscillatory shear mode with an applied angular frequency of 0.02 rad/s;
• (ii) tmaxDSC is the time in minutes to reach the maximum value of heat flow of crystallization at a temperature of 124° C. under quiescent conditions, measured in isothermal mode in a differential scanning calorimetry apparatus;
• and
• (iii) LCBI is the ratio of the measured mean-square radius of gyration Rg, measured by GPC-MALLS, to the mean-square radius of gyration for a linear PE having the same molecular weight.