Abstract: A process for the production of an in situ particulate polyethylene blend comprising contacting a magnesium/titanium based catalyst system including a particulate precursor with one or more alpha-olefins in each of two or more reactors connected in series, in the gas phase, under polymerization conditions, with the provisos that:(a) the particulate precursor has a particle size distribution span of no greater than about 1.

Abstract: A gas phase process for the production of a polyethylene blend comprising contacting ethylene and at least one alpha-olefin comonomer having 3 to 8 carbon atoms with a magnesium/titanium based catalyst system including an activator and a cocatalyst in each of two fluidized bed reactors connected in series, under polymerization conditions, with the provisos that:(a) the mixture of ethylene copolymer matrix and active catalyst formed in the first reactor in the series is transferred to the second reactor in the series;(b) other than the active catalyst referred to in proviso (a) and the cocatalyst referred to in proviso (e), no additional catalyst is introduced into the second reactor;(c) in the first reactor in which a low melt index copolymer is made:(1) the alpha-olefin is present in a ratio of about 0.01 to about 0.4 mole of alpha-olefin per mole of ethylene;(2) optionally, hydrogen is present in a ratio of about 0.001 to about 0.

Abstract: A process for substantially eliminating surface melt fracture during extrusion of a thermoplastic polymer such as a molten narrow molecular weight distribution, linear, ethylene copolymer, by incorporating into the thermoplastic polymer a wood rosin or wood rosin derivative.

Abstract: A process for substantially eliminating surface melt fracture during extrusion of a thermoplastic polymer such as a molten narrow molecular weight distribution, linear, ethylene copolymer, by using a die having a die land region defining opposing surfaces at least one of which is coated with a composition containing about 80% to 99% nickel and about 1% to 20% phosphorous.

Abstract: A process and apparatus as provided for substantially eliminating surface melt fracture during extrusion of a thermoplastic polymer such as a molten narrow molecular weight distribution, linear, ethylene copolymer, by using a die having a die land region defining opposing surfaces at least one of which is fabricated from an alloy containing 5 to 95 parts by weight zinc and 95 to 5 parts by weight of copper.

Abstract: Melt fracture of films made from LLDPE resins is reduced by using a die having a die land region fabricated from stainless steel and wherein the length of the die land to the width of the die gap is about 35:1 to about 60:1.

Abstract: A process for substantially eliminating surface melt fracture during extrusion of an ethylene polymer wherein the die land has a surface fabricated from a material which increases adhesion between the die land surface and the polymer.