Abstract: A process for eliminating low molecular-weight polymers from the recirculating gases of facilities carrying out ethylene polymerization or copolymerization at a pressure of 300 to 2500 bars and a temperature of 130.degree. C. to 350.degree. C., in which facilities the mixture of monomer and polymer leaving the reactor is expanded into a separator operating under a pressure of 50 to 500 bars. The gases are passed, at a temperature at least 20.degree. C. higher than the melting point of the low molecular-weight polymers, through at least one standard cyclone at an inlet velocity between 1 and 10 m/s. The gases are then cooled to a temperature lower than the melting point of the low molecular-weight polymers, and are then passed through at least one heated cyclone at an inlet velocity between 2 and 20 m/s.

Abstract: An organometallic halide having the formula:(RMX)(MX.sub.2).sub.a (MR.sub.2).sub.b (MH.sub.2).sub.cwherein a.ltoreq.0.45, b.ltoreq.0.15, and c.ltoreq.0.30, X is a halogen, R is a hydrocarbon radical, and M is a metal selected from the group consisting of magnesium, zinc, beryllium, and calcium is prepared by a continuous dry process by reacting an organic monohalide RX and a metal M in the form of convex solid grains of a size between 1 and 15 mm. The reaction temperature is lower than the temperature at which decomposition of the organometallic halide RMX begins and at least 10.degree. C. higher than the boiling point of the organic monohalide. The reaction may also take place in the presence of an organometallic derivative comprising a hydroxy group or an enolysable ketone group. The resulting organometallic halide may be used for the synthesis of anhydrous magnesium halide or for the reduction of titanium tetrachloride.

Abstract: Organo-lithium compounds of the formula: ##STR1## wherein R is an alkyl group of up to 5 carbon atoms, R' is either hydrogen or an alkyl group of up to 5 carbon atoms and n is an integer from 2 to 10. These bifunctional organo-lithium compounds are prepared without the use of any polar or complexing agent and are useful as polymerization initiators for the production of block copolymers.

Abstract: A process and apparatus for the polymerization of ethylene in at least one multizone reactor at a pressure of 300 to 2500 bars and at a temperature of 150 to 350.degree. C. The reaction mixture is passed from the reactor to a separator at a pressure of 50 to 500 bars in which the polymer separates from the gas. The polymer is then passed to a hopper at a pressure of 1 to 20 bars in which the major part of the gas remaining dissolved in the polymer is removed. The gas from the separator is recompressed and is returned only to the first zone of the reactor.

Abstract: New organo-lithium initiators, their synthesis, and their use. The initiators have the formula: ##STR1## IN WHICH R" is either a hydrogen atom or a methyl radial; either n is 1, in which case R' = H and m and p are integers, the sum of which is between 0 and 10 inclusive, or n is 2, R' then being an alkyl radical of 2 to 8 carbon atoms and m = p = 0; and R is an alkyl radical of 1 to 4 carbon atoms.The initiators are prepared by reacting compounds of the formula: ##STR2## WITH AN ALKYL-LITHIUM RLi in a non-polar solvent in the absence of any polar solvent or complexing agent.The initiators are used to prepare polydienes of high stereoregularity by reacting with a diene, and the polydiene is used to prepare a three-block or star copolymer by reacting with an anionically polymerizable monomer.

Abstract: The rheometer is located in a non-return branch of a molten polymer line and includes, in succession, a fixed-speed pump, a first capillary tube, and a second capillary tube in series with the first tube. The second tube has a diameter less than or equal to that of the first tube, and emerges into a fluid medium at regulated pressure. Pressure-sensors at the inlet of each tube determine the pressure loss between the inlet of each tube and the fluid medium at regulated pressure. The temperature is monitored by means that are at least party external to the body of the rheometer.

Abstract: A method for the accelerated transformation of the crystalline form of isotactic polybutene pipe, comprising moving the pipe linearly and subjecting the pipe while moving to a plurality of simultaneously inwardly directed radial stresses acting on the outer surface of the pipe along one or more radii of the same transverse cross section and in one or more adjacent cross sections of the pipe and apparatus for carrying out such method.

Abstract: In purifying polyolefins obtained by suspension polymerization to remove catalyst residues therefrom, the polymer is first separated from the polymerization medium and then degassed in the absence of air. Next the degassed polymer is deactivated by suspension in a liquid medium comprising a liquid hydrocarbon, an aliphatic alcohol having 1 to 4 C atoms, and an organic chloride which is an acid chloride or an alkyl chloride, the suspension being at a temperature of +30, +65.degree. C. Finally the deactivated polymer is separated from the liquid medium and washed with an aliphatic alcohol and/or a liquid hydrocarbon.

Abstract: Polyolefin compositions useful for making films having improved tensiometric properties and strength. The compositions comprise from 92 to 99% by weight of (1) a polyolefin having a melt index of 0.5 to 5 that is either isotactic poly-1-butene or a butene-ethylene copolymer containing less than 2% of ethylene units, and (2) from 1 to 8% of an ethylene-vinyl acetate copolymer having a vinyl acetate content of from 5 to 35% by weight and a melt index of from 0.5 to 5.

Abstract: Ethylene is polymerized, in the presence of hydrogen, at a temperature of 180.degree. to 340.degree. C and a pressure of 200 2,500 bars with a Ziegler catalyst in a stirred reactor having at least one first reaction zone and at least one second reaction zone. The reaction mixture is fed to a separator at a pressure of 80 to 400 bars. The improvement results from partially liquifying at least a part of the gas coming from the separator at a temperature of -50.degree. to +20.degree. C, releasing the pressure to a value of 10 to 60 bars, separating the partially liquified gas into a gas phase and a liquid phase, and recycling the gas phase to the second reaction zone and the liquid phase to the first reaction zone. The resulting polymer has a low melt index, a high polydispersity index, and superior physical properties compared to polymers prepared by conventional processes.

Abstract: A pressure vessel with an alloyed steel wall and having at least one ring of weldable steel secured thereon and wherein a temperature control jacket associated with said vessel is welded to said ring.

Abstract: Organo-lithium compounds of the formula: ##STR1## wherein R is an alkyl group of up to 5 carbon atoms, R' is either hydrogen or an alkyl group of up to 5 carbon atoms and n is an integer from 2 to 10. These bifunctional organo-lithium compounds are prepared without the use of any polar or complexing agent and are useful as polymerization initiators for the production of block copolymers.

Abstract: Radical polymerization of ethylene in the presence of an initiator and up to 500 ppm of a cyclic olefin having from 5 to 12 carbon atoms and a ring of 5 to 9 members or styrene and its alkyl homologues.

Abstract: Photodegradable polyethylene or polystyrene compositions of copolymers thereof containing up to 500 ppm of iron in the form of a ferrous carboxylic acid salt having a substituted alkyl chain of at least 6 carbon atoms.