Abstract: A process for producing ethylene polymers or ethylene copolymers comprising the steps of: (a) continuously polymerizing ethylene or ethylene and an .alpha.-olefin in a reaction mixture at a pressure of at least 300 kg/cm.sup.2 and a temperature of at least 130.degree. C. in the presence of a catalyst composed of a compound of a transition metal of groups IVa and VIa of the Periodic Table and an organometallic compound of a metal of groups I to III of the Periodic Table; and (b) adding a polyalkylene glycol to the reaction mixture to deactivate the catalyst.

Abstract: Acrylic prepolymer comprising:from 10 to 50% by weight of units derived from at least one alkyl acrylate, the alkyl group having from 4 to 12 carbon atoms,from 30 to 60% by weight of units derived from at least one alkyl methacrylate, the alkyl group having from 1 to 5 carbon atoms, andfrom 10 to 40% by weight of units derived from methyl acrylate.The prepolymer is used to encapsulate photocells, connected to one another by conducting wires and positioned on a support plate, by casting a resin into the space located between the support plate and a second protective plate, the resin being obtained by mixing 100 parts of the acrylic prepolymer, from 0.1 to 4 parts of a vanadium arenesulphonate and from 0.5 to 4 parts of a free-radical initiator, at a temperature between 10.degree. and 70.degree. C. and for a sufficient time to solidify the polymeric resin at the temperature selected.

Abstract: A catalyst for the polymerization of ethylene comprising at least one halogenated compound of a transition metal of Groups IV to VI of the Periodic System and at least one aromatic silicon compound having the formula .phi..sub.n Si(OH).sub.4-n, in which .phi. is a substituted or unsubstituted aromatic or polyaromatic ring compound having from 6 to 15 carbon atoms and 1.ltoreq.n.ltoreq.3, said silicon compound being present in a molar ratio of between 0.2 and 2 inclusive with respect to said transition metal. Polymerization of ethylene may be carried out under a pressure of between 200 to 2500 bars and at a temperature of between 170.degree. and 300.degree. C. with the catalyst of this invention.

Abstract: An apparatus for evacuating the gases resulting from the decomposition of industrial process gases, such as ethylene, contained in a vessel under high pressure is adjacent to the vessel. The apparatus comprises:(1) at least one safety means separating the apparatus from the vessel;(2) a reservoir with a volume which is 2 to 100 times that of the vessel;(3) at least one connecting pipe between the vessel and the reservoir; and(4) at least one chimney between the reservoir and the atmosphere.The apparatus is useful for the recovery of decomposition gases for the purpose of preventing atmospheric pollution. The risk of explosion is reduced by evacuating decomposition gases through the apparatus.

Abstract: A polymerization activator for polymerizing ethylene comprising a dialkylaluminum monofluoride mixed with minor amounts of at least one of dialkylaluminum hydride or halide and a trialkylaluminum. The activator preferably corresponds to the general formula (AlR.sub.2 F)(AlR.sub.2 H).sub.b (AlR.sub.3).sub.c or the general formula (AlR.sub.2 F)(AlR.sub.2 X).sub.a wherein R is an alkyl group having 1 to 12 carbon atoms, 0.1.ltoreq.b.ltoreq.0.4, 0.05.ltoreq.c.ltoreq.0.2, X is a halogen other than fluorine, and 0.1.ltoreq.a.ltoreq.0.4. The activator is used in a catalytic system including at least one halide of a transition metal of Group IVB to VIB, the valency of the metal in the halide being not more than 3 and the atomic ratio of aluminum in the activator to transition metal in the catalyst lying between 0.1 and 10. The catalytic system is used in a high pressure and temperature process for polymerizing or copolymerizing ethylene.

Abstract: A process for polymerizing ethylene in the presence of a catalyst system comprising at least two halogen compounds of transition metals, one of which has the formula (TiCl.sub.3,Y3 AlCl.sub.3)(MY.sub.3).sub.x (MgYZ).sub.y, where M is a transition metal of Group VB or V1B, X is a halogen and 0.3.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.20, and a Group I to III hydryde or organometallic activator and the mean residence time of the catalyst system in the polymerization reactor is between 2 and 100 seconds.

Abstract: A modified copolymer of ethylene and of at least one .alpha.-olefin having from 3 to 12 carbon atoms, comprising from 0.5 to 10 mole percent of units derived from the .alpha.-olefin, wherein the measured limiting viscosity of the copolymer is between 1.5 and 10 times the limiting viscosity of the copolymer calculated from the molecular weight distribution of the copolymer. Process for producing these copolymers employing at least one free-radical initiator.

Abstract: A catalyst comprising the product obtained by bringing into contact (a) a compound of magnesium comprising at least one species selected from the group consisting of magnesium monohalides (MgX), halo-magnesium hydrides (HMgX) and magnesium hydride (MgH.sub.2), X being a halogen and the said species MgX or HMgX being obtained by thermal decomposition of a powdery organo-magnesium halide R.sub.1 MgX wherein R.sub.1 is an organic radical; and (b) at least one halide of a transistion metal selected from the group consisting of titanium and vanadium, the valency of said metal in said halide being lower than or equal to 3, the quantities of (a) and (b) being such that the atomic ratio of magnesium to said transistion metal is between 1 and 25, and a catalyst system including the catalyst that is suitable for use in the polymerization of olefins and particularly ethylene.

Abstract: Polyethylene is produced in at least one reactor under a pressure of 800 to 2500 bars and a temperature of 150.degree. to 350.degree. C., and the reaction mixture exiting the reactor through an expansion valve and supplied to a separator under a pressure of 50 to 400 bars is cooled by passing a flow Q of the mixture through a turbine. The turbine comprises at least one stage with a fixed nozzle and a bladed wheel having a rotation speed of between 12,000 and 40,000 r.p.m. Ethylene discharged from the separator is recycled to the inlet of a compressor, and the discharge from the compressor is supplied to the reactor.

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: A process for preparing graft styrene copolymers is effected by a two-stage polymerization of styrene in the presence of an EPDM elastomer and styrene block copolymer. The resultant graft styrene copolymer has a fine microstructure, good impact resistance and good resistance to aging.

Abstract: A distribution cap for a multitubular falling heat exchanger, in which the exchanger has a bundle of parallel tubes, an entrance channel for the tubes and a perpendicularly disposed distribution plate surrounding the entrance end of the tubes, the distribution cap is located in the entrance channel above the distribution plate and over the entrance ends of the tubes, and has cylindrical sidewalls and a closed top having sides that slope downwardly toward the cylindrical sidewalls of the cap.

Abstract: A halogen-containing catalyst for the polymerization of ethylene or copolymerization of ethylene and .alpha.-olefins having from 3 to 8 carbon atoms and a process for their preparation. The catalyst has the general formula: M.sub.n Mg(OR).sub.2-m X.sub.m+4n, wherein M is a metal of groups IVa to VIa of the Periodic Tables, X is a halogen, R is an alkyl radical containing from 1 to 4 carbon atoms, 0<m<2, and 0.05<n<1.

Abstract: Polyethylene is produced in at least one reactor under a pressure of 800 to 2500 bars and a temperature of 150.degree. to 350.degree. C., and the reaction mixture exiting the reactor through an expansion valve and supplied to a separator under a pressure of 50 to 400 bars is cooled by passing a flow Q of the mixture through a turbine. The turbine comprises at least one stage with a fixed nozzle and a bladed wheel having a rotation speed of between 12,000 and 40,000 r.p.m. Ethylene discharged from the separator is recycled to the inlet of a compressor, and the discharge from the compressor is supplied to the reactor.

Abstract: A composition for sealing products comprising from 35 to 95 weight percent of at least one distillation product selected from the group consisting of bitumens and soft pitches, and from 5 to 65 weight pecent of a terpolymer having a melt index between 1 and 10 dg/minute and comprising: (i) from 88 to 98.7 mole percent of units derived from ethylene (ii) from 1 to 10 mole percent of units derived from an ester selected from alkyl acrylates and methacrylates, wherein said alkyl group has from 1 to 6 carbon atoms, and (iii) from 0.3 to 3 mole percent of units derived from maleic anhydride.

Abstract: Polynorbornenes are cured with isocyanates optionally in the presence of polyols to yield elastomeric products having improved mechanical properties, particularly improved compression moduli and residual set while retaining the desired rebound elasticity values.

Abstract: Acrylic prepolymer comprising:from 10 to 50% by weight of units derived from at least one alkyl acrylate, the alkyl group having from 4 to 12 carbon atoms,from 30 to 60% by weight of units derived from at least one alkyl methacrylate, the alkyl group having from 1 to 5 carbon atoms, andfrom 10 to 40% by weight of units derived from methyl acrylate.The prepolymer is used to encapsulate photocells, connected to one another by conducting wires and positioned on a support plate, by casting a resin into the space located between the support plate and a second protective plate, the resin being obtained by mixing 100 parts of the acrylic prepolymer, from 0.1 to 4 parts of a vanadium arenesulphonate and from 0.5 to 4 parts of a free-radical initiator, at a temperature between 10.degree. and 70.degree. C. and for a sufficient time to solidify the polymeric resin at the temperature selected.

Abstract: A copolymer based on ethylene and propylene, having a density of between 0.933 and 0.946 g/cm.sup.3 and a melt index of between 2 and 10 dg/min, wherein the copolymer has from 3 to 27 alkyl groups per 1000 carbon atoms in the molecule and wherein its density .rho. and its proportion m of alkyl groups in the molecule satisfy the relationship 0.948.ltoreq..rho.+0.71 m.ltoreq.0.9525. The copolymer is produced by feeding a flux comprising from 80 to 95% by weight of ethylene and from 5 to 20% by weight of propylene into at least one reactor in stationary operation, the reactor having at least one reaction zone; and copolymerizing the ethylene and propylene in the reactor at a pressure of from 300 to 2500 bar and a temperature of from 180.degree. to 320.degree. C. in the presence of a Ziegler type catalyst system.

Abstract: The danger of explosion due to decomposition of high-pressure industrial process gases, such as ethylene, is reduced by maintaining in an inert atmosphere at least part of an evacuation system included between a pressurized vessel within which the decomposition may take place, on the one hand, and the atmosphere, on the other.

Abstract: A continuous process for manufacturing quick-setting phenolic foams is improved by using as the hardening agent a concentrated, substantially anhydrous solution of boron trioxide, and using as the blowing agent an organic liquid having a boiling point of 20.degree.-80.degree. C. Curing times are shortened and the resultant foam, having uniformly molecularly dispersed therein about 0.25-10.5% by weight of boron, calculated as boric anhydride, has substantially uniform cells, improved fire resistance characteristics and superior mechanical properties.