A process-for preparing a polyethylene composition comprising the following steps: (a) providing at least a first amount of ethylene to a first gas-phase reactor; (b) providing at least a first amount of Ziegler-Natta catalyst to the first gas-phase reactor to produce at least a first amount of polyethylene polymer within the first gas-phase reactor; (c) transferring at least a portion of the first amount of polyethylene polymer and at least a portion of the first amount of Ziegler-Natta catalyst to a second gas-phase reactor; (d) providing at least a second amount of ethylene in the presence of a first amount of hydrogen to the second gas-phase reactor to obtain a second polyethylene polymer to produce a polyethylene composition comprising the first polyethylene polymer and the second polyethylene polymer, wherein the polyethylene composition comprises a density of greater than about 0.950 g/cm 3, a ratio of MIF/MIP from about 17 to about 25, a long-chain branching index lower than about 0.70, and: from about 40 to about 60 % by weight of an ethylene homopolymer or copolymer with density equal to or greater than about 0.960 g/cm 3 and melt flow index at 190 °C with a load of 2.16 kilograms of about 5 to about 20 grams/10 minute; and from about 40 to about 60 % by weight of an ethylene homopolymer or copolymer having a MIE value lower than the MIE value of; and the Ziegler-Natta catalyst comprising a solid catalyst component comprising a titanium compound on a magnesium support and an organoaluminum compound, wherein the solid catalyst component is produced by contacting the titanium compound with magnesium chloride or a precursor magnesium compound and heating to a temperature ranging from about 130 °C to about 150 °C, wherein at least one of the first or second gas-phase reactors comprises a first and second polymerization zone, the first polymerization zone having a first hydrogen pressure and the second polymerization zone having a second hydrogen pressure, wherein the first hydrogen pressure and the second hydrogen pressure are different such that at least a portion of the second amount of ethylene moves through the first and second polymerization zones and at least a portion of a gas mixture of each polymerization zone is partially or totally prevented from entering the other zone. (a) providing at least a first amount of ethylene to a first gas-phase reactor; (b) providing at least a first amount of Ziegler-Natta catalyst to the first gas-phase reactor to produce at least a first amount of polyethylene polymer within the first gas-phase reactor; (c) transferring at least a portion of the first amount of polyethylene polymer and at least a portion of the first amount of Ziegler-Natta catalyst to a second gas-phase reactor; (d) providing at least a second amount of ethylene in the presence of a first amount of hydrogen to the second gas-phase reactor to obtain a second polyethylene from about 40 to about 60 % by weight of an ethylene homopolymer or copolymer with density equal to or greater than about 0.960 g/cm 3 and melt flow index at 190 °C with a load of 2.16 kilograms of about 5 to about 20 grams/10 minute; and from about 40 to about 60 % by weight of an ethylene homopolymer or copolymer having a MIE value lower than the MIE value of; and