Abstract: A gas phase process for producing olefin polymer graft copolymers, including providing a reaction apparatus having first and second reaction zones operatively connected to each other into which particles of an olefin polymer and a free-radical polymerizable monomer are fed while maintaining free-radical polymerization conditions and a substantial non-oxidizing environment in said zones and from which the grafted copolymer product is discharged. An apparatus suitable for practicing this process is also disclosed.

Abstract: Process for the gas-phase polymerization of ethylene and ethylene mixtures with .alpha.-olefins CH.sub.2 .dbd.CHR in the presence of a high activity catalyst comprising a titanium compound containing at least one Ti-halogen bond, supported on magnesium dichloride in active form said process comprising the steps of: (a) contacting the catalyst component; (b) prepolymerizing ethylene or ethylene mixtures with .alpha.-olefins in order to produce a polymer amount of from approximately 5 g per g of solid component, up to an amount corresponding to about 10% of the final catalyst yield; (c) polymerizing ethylene or ethylene mixtures with .alpha.-olefins in the gas-phase, in the presence of the prepolymer-catalyst system obtained in (b), while maintaining in the gas phase a molar concentration concentration of the alkane comprised between 20 and 90% with respect to the total gases.

Abstract: Gas-phase process for the preparation of polymers and copolymers of olefins CH.sub.2 .dbd.CHR, carried out in at least 2 fluidized or mechanically agitated bed gas-phase reactors operating under different reaction conditions so as to obtain different polymers in the different reactors; the process is characterized in that the polymer is at least partially recycled among the different reactors by using ratios of the flow rate of circulation among the different reactors to the discharge flow rate comprised between 2 and 6.

Abstract: Process for gas-phase polymerization carried out in two interconnected polymerization zones, to which one or more .alpha.-olefins CH.sub.2 .dbd.CHR are fed in the presence of catalyst under reaction conditions and from which the polymer product is discharged. The process is characterized in that the growing polymer flows through a first polymerization zone under fast fluidization conditions, leaves said first zone and enters a second polymerization zone through which it flows in a densified form under the action of gravity, leaves said second zone and is reintroduced into the first polymerization zone, thus establishing a circulation of polymer around the two polymerization zones. The novel process allows olefins to be polymerized in the gas phase with high productivity per unit volume of the reactor without incurring the problems of the fluidized-bed technologies of the known state of the art.

Abstract: A gas phase process for producing olefin polymer graft copolymers, including providing a reaction apparatus having first and second reaction zones operatively connected to each other into which particles of an olefin polymer and a free-radical polymerizable monomer are fed while maintaining free-radical polymerization conditions and a substantial non-oxidizing environment in said zones and from which the grafted copolymer product is discharged. An apparatus suitable for practicing this process is also disclosed.

Abstract: A process for polymerizing olefins using a fluidized bed, in which the monomer entry point is located at a point above the bed height. A pre-polymerization step can be conducted using a Z/N catalyst along with an alkane diluent, and resultant liquid phase is introduced into the fluidized bed above the bed height. The process may use several reactors in series arrangement.

Abstract: A process for the production of expandable granules of thermoplastic polymers comprising: (a) the extrusion of the polymer in which an expanding agent is incorporated, through a die-head in order to obtain an expandable polymer; (b) immediate cooling of this polymer in water, kept at a temperature at which the polymer remains in the non-expanded state, but not lower than the Tg of the expandable polymer; (c) cutting of the polymer to granules in water immediately at the outlet of the die-head, and (d) annealing of the thus obtained granules, by slow cooling in a temperature range comprised between at least +5.degree. C. and at least -5.degree. C. the Tg of the expandable polymer, wherein the cooling and the cutting of the polymer to granules and the annealing thereof are carried out under pressure.

Abstract: The halogen and organic substances content of the catalyst residues in alpha-olefin crystalline (co)-polymers prepared with catalysts obtained by reacting:(a) a metallorganic Al compound with(b) a Ti compound supported on a Mg halide, in which an electron-donor is combined with the Ti compound and/or the Mg compound and optionally with (a),are reduced by passing a stream of superheated steam (optionally mixed with other gaseous fluids) over the polymer in powder form at a temperature of 105.degree.-140.degree. C. and under a pressure of 0.1-10 kg/cm.sup.2 gauge, the steam/polymer ratio being comprised between 0.10 and 1 by weight.

Abstract: Organic-solvent solutions of polycarbonates containing impurities, e.g., sodium chloride and sodium carbonate formed during the preparation of the polycarbonates, and/or catalysts, are purified by sending aqueous emulsions of polycarbonates in water-immiscible organic solvents, in particular the aqueous emulsions coming from the various purification phases of the organic polycarbonate solutions obtained in the synthesis, through a layer of fibers in which the dispersed droplets of the emulsion coalesce, with the formation of two layers each consisting essentially of one of the two separate phases of the emulsion.