Abstract: A process for producing an olefin polymer employs a gas phase polymerization reactor in fluid communication with a vent column and a product discharge system. The discharge system can include first and second pairs of lock hoppers, where each pair includes an upstream lock hopper connected by a valve to the reactor and a downstream lock hopper connected by a valve to the upstream lock hopper and by a further valve to a product recovery system, and where a first cross-tie can be provided between the upstream lock hoppers of the first and second pairs of lock hoppers and a second cross-tie can be provided between the downstream lock hoppers of the first and second pairs of lock hoppers. Upon reaching the vent column's maximum removal capacity, additional gas can be removed from the reactor by reducing the frequency of opening the second cross-tie between the downstream lock hoppers.

Abstract: Polyethylene copolymers with a structure that provides improved film properties are provided. The copolymers can have a density of about 0.905 to about 0.911 g/cm3. The copolymers can also have a DRI/I2 ratio of about 0.0008 to about 0.060, an I2 value of about 0.6 to about 3.8 dg/min, and an I21 value of about 8 to about 57 dg/min. The copolymers having those properties can be produced by introducing ethylene and at least one other olefin comonomer to a single reactor at a comonomer/ethylene mole ratio of about 0.02 to about 0.03 and polymerizing at a temperature of about 76.7° C. to about 80.6° C. and a pressure of about 1,724 kPa to about 2,413 kPa. The copolymers can be used to make films having a 21 mol % O2 transmission rate of about 150 to about 200 cc/100 in2/24 hr. and hot tack seal initiation temperatures of about 65° C. to 80° C.

Abstract: Provided are polyethylene copolymers with improved stress crack resistance, methods for making such copolymers, and films made from the same. The polyethylene copolymers include at least 95 wt % ethylene and at most 5 wt % of at least one comonomer having 3 to 18 carbon atoms; and further have a 30% single point notched constant tensile load of at least 1,000 hours, a density of 0.931 to 0.936 g/cm3, a melt index (I2) of 0.1 to 0.5 g/10 min, and a 25-75 chemical composition distribution index of 0.3 or more.

Abstract: Methods for startup of an extruder include (a) initiating feed of a polymer resin to the extruder using a volumetric feeder such that, where the melt index of the polymer resin is less than 10 g/10 min (ASTM D1238 at 230° C., 2.16 kg), the volumetric feeder is operated at a first volumetric feeder speed; or (b) initiating feed of a polymer resin to the extruder using the volumetric feeder such that, where the melt index of the polymer resin is 10 g/10 min or greater, the volumetric feeder is operated at a second volumetric feeder speed greater than the first. The first volumetric feeder speed can range from about 20% to about 25% of the volumetric feeder max speed; and the second volumetric feeder speed can range from about 30% to about 35% of the volumetric feeder max speed.

Abstract: Polyethylene copolymers with a structure that provides improved film properties are provided. The copolymers can have a density of about 0.905 to about 0.911 g/cm3. The copolymers can also have a DRI/I2 ratio of about 0.0008 to about 0.060, an I2 value of about 0.6 to about 3.8 dg/min, and an I21 value of about 8 to about 57 dg/min. The copolymers having those properties can be produced by introducing ethylene and at least one other olefin comonomer to a single reactor at a comonomer/ethylene mole ratio of about 0.02 to about 0.03 and polymerizing at a temperature of about 76.7° C. to about 80.6° C. and a pressure of about 1,724 kPa to about 2,413 kPa. The copolymers can be used to make films having a 21 mol % O2 transmission rate of about 150 to about 200 cc/100 in2/24 hr. and hot tack seal initiation temperatures of about 65° C. to 80° C.