Disclosed are methods for the production of polymers, including random copolymers (RCPs), in single reactor gas or slurry phase polymerization processes, and polymer compositions produced therefrom. The methods enable polymers having low melting temperatures to be made in gas and slurry phase polymerization processes, where they conventionally could not be made in these processes due to stickiness and fouling problems in the reactor.

Methods for controlling the productivity of an olefin polymer in a polymerization reactor system using a halogenated hydrocarbon compound are disclosed. The productivity of the polymer can be increased via the addition of the halogenated hydrocarbon compound.

A polyethylene resin having a multimodal molecular weight distribution comprising at least two polyethylene fractions A and B, fraction A being substantially free of comonomer and having a lower weight average molecular weight and a higher density than fraction B, each fraction prepared in different reactors of two reactors connected in series in the presence of a Ziegler-Natta catalyst system, the polyethylene resin having a density of from 0.950 to 0.965 g/cm.sup.3 and a melt index MI2 of from 0.5 to 5 g/10 min.

A polyethylene resin having a multimodal molecular weight distribution comprising at least two polyethylene fractions A and B, fraction A being substantially free of comonomer and having a lower weight average molecular weight and a higher density than fraction B, each fraction prepared in different reactors of two reactors connected in series in the presence of a Ziegler-Natta catalyst system, the polyethylene resin having a density of from 0.950 to 0.965 g/cm.sup.3 and a melt index MI2 of from 0.5 to 5 g/10 min.

A polyethylene resin having a multimodal molecular weight distribution comprising at least two polyethylene fractions A and B, fraction A being substantially free of comonomer and having a lower weight average molecular weight and a higher density than fraction B, each fraction prepared in different reactors of two reactors connected in series in the presence of a Ziegler-Natta catalyst system, the polyethylene resin having a density of from 0.950 to 0.965 g/cm.sup.3 and a melt index MI2 of from 0.5 to 5 g/10 min.

A process for the preparation of polyethylene by polymerizing in a slurry ethylene and optionally one or more C.sub.3 to C.sub.10 alpha-olefins in a reactor system comprising a polymerization reactor and one or more first heat exchangers located outside the polymerization reactor where the slurry in the polymerization reactor is cooled by withdrawing slurry from the polymerization reactor, cooling the slurry in the one or more first heat exchangers and returning the cooled slurry to the polymerization reactor, wherein the one or more first heat exchangers are cooled by a first coolant having a temperature of 29 C. or higher.

A process for the preparation of polyethylene by polymerizing in a slurry ethylene and optionally one or more C.sub.3 to C.sub.10 alpha-olefins in a reactor system comprising a polymerization reactor and one or more first heat exchangers located outside the polymerization reactor where the slurry in the polymerization reactor is cooled by withdrawing slurry from the polymerization reactor, cooling the slurry in the one or more first heat exchangers and returning the cooled slurry to the polymerization reactor, wherein the one or more first heat exchangers are cooled by a first coolant having a temperature of 29 C. or higher.

A process for the preparation of polyethylene by polymerizing in a slurry ethylene and optionally one or more C.sub.3 to C.sub.10 alpha-olefins in a reactor system comprising a polymerization reactor and one or more first heat exchangers located outside the polymerization reactor where the slurry in the polymerization reactor is cooled by withdrawing slurry from the polymerization reactor, cooling the slurry in the one or more first heat exchangers and returning the cooled slurry to the polymerization reactor, wherein the one or more first heat exchangers are cooled by a first coolant having a temperature of 29 C. or higher.

A process for the preparation of polyethylene by polymerizing in a slurry ethylene and optionally one or more C.sub.3 to C.sub.10 alpha-olefins in a reactor system comprising a polymerization reactor and one or more first heat exchangers located outside the polymerization reactor where the slurry in the polymerization reactor is cooled by withdrawing slurry from the polymerization reactor, cooling the slurry in the one or more first heat exchangers and returning the cooled slurry to the polymerization reactor, wherein the one or more first heat exchangers are cooled by a first coolant having a temperature of 29 C. or higher.

A process for the preparation of polyethylene by polymerizing in a slurry ethylene and optionally one or more C.sub.3 to C.sub.10 alpha-olefins in a reactor system comprising a polymerization reactor and one or more first heat exchangers located outside the polymerization reactor where the slurry in the polymerization reactor is cooled by withdrawing slurry from the polymerization reactor, cooling the slurry in the one or more first heat exchangers and returning the cooled slurry to the polymerization reactor, wherein the one or more first heat exchangers are cooled by a first coolant having a temperature of 29 C. or higher.