Abstract: The present invention relates to an improvement for gas-phase olefin polymerization process having relatively high bed bulk density. The improvement involves the use of mixed external electron donors when polymerizing propylene in a gas-phase reactor having a polymer bed with a bulk density greater than 128 kg/m3, optionally with one or more comonomers, wherein the mixed electron donor system comprises at least a first external electron donor and a second external electron donor, and wherein the first external electron donor is a carboxylate compound.

Abstract: The present invention relates to an improvement for gas-phase olefin polymerization process having relatively high bed bulk density. The improvement involves the use of mixed external electron donors when polymerizing propylene in a gas-phase reactor having a polymer bed with a bulk density greater than 128 kg/m3, optionally with one or more comonomers, wherein the mixed electron donor system comprises at least a first external electron donor and a second external electron donor, and wherein the first external electron donor is a carboxylate compound.

Abstract: The invention relates to methods of using polymers in the waste stream obtained from the production of powder coat. The polymer in the waste stream can be cured with that in another waste stream or with a virgin polymer.

Abstract: A lightweight manhole cover assembly includes a cover and a base, with the cover including an inner surface having a plurality of ribs extending therefrom. The base includes an inner surface having a plurality of receptacles extending therefrom. The receptacles of the base have a layout that corresponds to the ribs of the cover, such that the ribs are adapted to be inserted into the receptacles.

Abstract: The invention relates to methods of using polymers in the waste stream obtained from the production of powder coat. The polymer in the waste stream can be cured with that in another waste stream or with a virgin polymer.

Abstract: A screw cap assembly for clamping a cover in an opening includes a threaded rod adapted to engage the cover and a clamp threadably connected to the threaded rod. A retainer is adapted to support the threaded rod and to limit the range of movement of the clamp along the threaded rod. Rotational movement of the threaded rod causes the clamp to rotate and travel toward the cover until it engages a first abutment of the retainer, which prevents further rotational movement of the clamp, such that only movement toward the cover in a direction parallel the threaded rod is permitted. Rotational movement of the threaded rod in an opposite direction causes the clamp to rotate and travel away from the cover until the clamp engages a second abutment of the retainer adapted to engage the clamp to prevent further movement of the clamp away from the cover.

Abstract: Gas phase polymerization processes are disclosed which utilize unsupported soluble transition metal coordination catalysts. The catalysts are introduced into the reactor as a solution.

Abstract: Methylene bridged derivatives of novel cyclopentadienyl dicarbollide complexes of titanium, zirconium and hafnium display high activity as ethylene polymerization catalysts in the absence of a cocatalyst.

Abstract: A process for the production of polyethylene comprising contacting ethylene or a mixture comprising ethylene and one or more alpha-olefins and, optionally, one or more diolefins, under polymerization conditions, with a catalyst system comprising:(a) a particulate catalyst precursor based on titanium or vanadium;(b) polypropylene support particles to which the catalyst precursor particles are bonded; and(c) a hydrocarbyl aluminum cocatalyst.

Abstract: Stereoregular polymers having a molecular weight distribution of less than 5.0 and an isotactic index in excess of 96 percent are produced by polymerizing an alpha-olefin having 3 to 8 carbon atoms in a low pressure gas phase fluid bed process at a temperature in excess of 80.degree. C. employing a heat stable catalyst system comprising (a) a solid catalyst component containing magnesium, titanium, halide and a polycarboxylic acid ester containing two coplanar ester groups attached to adjacent carbon atoms, as inside electron donor, (b) an organoaluminum cocatalyst, and (c) a silicon compound containing a silicon-oxygen-carbon linkage, as outside electron donor.