Abstract: In a gas phase fluidized bed polymerization process for the production of polyolefin polymers, such as polyethylene polymers or polypropylene polymers, loss of ethylene or propylene accompanying inert gas purging is reduced by passing an ethylene- or propylene-containing purge stream through a vent column to contact a hydrocarbon liquid flowing through the vent column contercurrent to the purge stream whereby unreacted ethylene or propylene in the purge stream portion is dissolved in the hydrocarbon liquid to produce an ethylene- or propylene-enriched liquid stream and an ethylene- or propylene-depleted gaseous stream. The ethylene- or propylene-enriched liquid stream is then recycled to the fluidized bed reactor, while at least part of the ethylene- or propylene-depleted gaseous stream is purged.

Abstract: Thermoplastic granules are finished by blending thermoplastic granules with additive material to form a masterblend; intensively mixing the masterblend with additional thermoplastic granules under conditions (1) to increase the temperature of the thermoplastic to its softening temperature and (2) to increase the bulk density of the granules; and withdrawing and cooling the mixture to form free flowing granules containing additives thereon or therein.

Abstract: Rotational mold grade resin is made by subjecting polyolefin to the following process: (1) polyolefin granules are blended with additives to form a masterblend; (2) the masterblend is intensively mixed with additional resin granules to shape the granules, reduce particle size and disperse additives; (3) the intermixed material is cooled and (4) large particles are removed and recycled.