A method of controlling long chain branching in an ethylene-based polymer includes polymerizing ethylene with one or more optional monomers to form an ethylene-based polymer, and controlling a degree of long chain branching (LCB) in the ethylene-based polymer. The degree of LCB ranges from 0.1 per 1000 carbon atoms in the polymer backbone to 10 per 1000 carbon atoms in the polymer backbone, as measured by .sup.13CNMR. The degree of LCB is controlled by adding one or more branched vinyl ester to the polymerizing step in an amount ranging from 0.01 mol % to 5.0 mol %, relative to total monomer content. A polymer composition contains the ethylene-based polymer. An article includes the polymer composition containing the ethylene-based polymer.

Methods for operating a high pressure olefin polymerization reactor include the steps of introducing an initiator stream containing ethylene and an initiator compound through an initiator nozzle into the reactor, introducing an olefin stream containing ethylene and an optional comonomer through an olefin nozzle into the reactor, and polymerizing ethylene and optionally the comonomer in the presence of the initiator stream in the reactor under high pressure polymerization conditions to produce an ethylene polymer. The amount of ethylene in the initiator stream is from 0.01 to 2 wt. % of the amount of ethylene in the olefin stream. An injection nozzle that can be used in conjunction with the high pressure reactor also is described.

Methods for operating a high pressure olefin polymerization reactor include the steps of introducing an initiator stream containing ethylene and an initiator compound through an initiator nozzle into the reactor, introducing an olefin stream containing ethylene and an optional comonomer through an olefin nozzle into the reactor, and polymerizing ethylene and optionally the comonomer in the presence of the initiator stream in the reactor under high pressure polymerization conditions to produce an ethylene polymer. The amount of ethylene in the initiator stream is from 0.01 to 2 wt. % of the amount of ethylene in the olefin stream. An injection nozzle that can be used in conjunction with the high pressure reactor also is described.

A method for producing an ethylene-acrylic acid copolymer may minimize the neck-in phenomenon of the strand by discharging the copolymer strand by controlling the discharging temperature of the produced copolymer to be 200 to 300° C., has excellent workability, processability, and moldability, and melt index (MI) is easy to control. In addition, the ethylene-acrylic acid copolymer produced by this method has the effect of having high melt tension.

A hotmelt adhesive composition includes a polymer produced from ethylene, one or more branched vinyl ester monomers, and optionally, vinyl acetate, and a tackifier. A method for producing the hotmelt adhesive composition includes adding a polymer produced from ethylene, one or more branched vinyl ester monomers, and optionally, vinyl acetate and a tackifier into a mixer, optionally adding wax and/or antioxidant into the mixer, and mixing the polymer and the tackifier, and the optional wax and/or antioxidant at a temperature in a range from 150° C. to 200° C. to form the hot melt adhesive composition. A method for bonding a substrate to a similar or dissimilar substrate includes applying the hotmelt adhesive composition to at least one substrate; and bonding the substrate and the hotmelt adhesive composition together. A multi-layer article comprises at least one layer of the hotmelt adhesive compositions and one or more substrate layers.

The invention relates to a process for the preparation of low density polyethylene (LDPE) wherein the polymerisation takes place in a tubular reactor at peak temperatures ranging from 180° C. to 350° C. and at pressures ranging from 150 to 350 MPa and wherein the total effective length of the polymerisation reactor divided by the number of reaction zones is in the range from 230 to 350 m.

This disclosure relates to systems and processes for cooling polymer product mixtures manufactured at high pressure. The processes of the invention involve cooling and then subsequently reducing the pressure of the product mixture from the reactor. In the systems of the invention, a product cooler is located downstream of the high pressure reactor and upstream of a high pressure let down valve.

Provided are an apparatus and a method for manufacturing high-pressure method low-density polyethylene, the apparatus and the method having excellent characteristics that a chain transfer agent can be supplied by a simpler apparatus, a deviation (variation) of the concentration of the chain transfer agent supplied to a reactor can be reduced, and compression energy of the chain transfer agent can be reduced. An apparatus for manufacturing high-pressure method polyethylene includes a chain transfer agent supply line that is a line connected to a low pressure recycle ethylene supply line for supplying a chain transfer agent.

Provided are an apparatus and a method for manufacturing high-pressure method low-density polyethylene, the apparatus and the method having excellent characteristics that the amount of smoke generated during processing of a polyethylene to be obtained is small, and the number of fish eyes contained in a film formed from the polyethylene is small. An apparatus for manufacturing high pressure method polyethylene includes: an ethylene supply line that is a line branched from a high pressure recycle ethylene line and connected to a recycle ethylene holding drum for decompressing high pressure recycle ethylene from the high pressure recycle ethylene line and supplying the decompressed recycle ethylene to the recycle ethylene holding drum; and the recycle ethylene holding drum that is a drum for holding the decompressed recycle ethylene through the ethylene supply line.

Methods for producing polyethylene compositions having broader melt index ratio and narrower molecular weight distribution in high pressure multi-feed tubular reactors are provided. The methods are useful in multi-feed tubular reactors comprising three or more reaction zones. The first reaction zone or the first and second reaction zone having a peak temperature that is lower than standard peak temperatures for polymerization of ethylene monomer in a tubular reactor.