Abstract: A hollow container made of thermoplastic material, having its base connected to its side wall by an integral, peripheral rounded molding, and having its base formed of at least two substantially planar, axially staggered, concentric annular zones connected together by alternating molded portions of rounded cross section.

Abstract: Polymerization and copolymerization is carried out in the presence of an improved transition metal based catalyst. The catalyst is obtained by activating with an organometallic compound, the solid product which results from the reaction of a halogen containing transition metal compound with an alkoxy metal compound of the formula X.sub.m-n M(OR).sub.n wherein M is at least one metal selected from the elements of Groups Ia, IIa, IIb, IIIa and VIIb of the Periodic Table, X is a monovalent inorganic radical, R is a monovalent hydrocarbon radical, m is the valence of M and n is an integer such that 1 .ltoreq. n .ltoreq. m.

Abstract: Alumina-supported halogen-containing transition metal compounds prepared in such manner that (a) the transition metal compound is chemically bound to and supported by an activated alumina having a high surface area and an internal pore volume greater than 0.8 cc/g., (b) the concentration of the transition metal compound chemically bound to the support is greater than 10 grams of transition metal per kilogram of activated alumina, and (c) the atom ratio of halogen to transition metal on the support is higher than that of the halogen-containing transition metal compound which is used and preferably greater than 3:1, have been found to be unusually effective cocatalysts for the polymerization of ethylene and other .alpha.-olefins. These supported cocatalysts, which may be used to produce polyethylene as well as interpolymers of ethylene with other .alpha.-olefins and with diolefins, are prepared by heating an alumina hydrate (such as boehmite) to a temperature in the range from about 500.degree. C. to 900.

Abstract: This invention relates to an improved process for the polymerization and copolymerization of olefins, to the novel catalytic component and catalytic system used for such polymerization and to a process for preparing such catalytic system, in which the polymerization of the olefins is carried out in the presence of a catalytic system comprising an organometallic compound of a metal of Group I, II, or III or the Periodic Table and a solid catalytic component obtained by reacting together metallic magnesium, a hydroxylated organic compound, an organic oxygenated compound of a metal of Group IVb, Vb, or VIb of the Periodic Table, an aluminum halide, and a halogen-containing compound of a metal of Group IVb, Vb or VIb of the Periodic Table.

Abstract: Process for the polymerization of vinyl chloride in aqueous suspension in the presence of dialkyl peroxydicarbonates in which the polymer is treated with a monobasic hydroxide at the end of polymerization and before the unreacted vinyl chloride is removed. The alkaline treatment is advantageously applied to polymers that are subsequently subjected to steam stripping.The treatment improves the initial heat stability of vinyl chloride polymers.

Abstract: Process for the polymerization of vinyl chloride in aqueous suspension in the presence of a dispersing system comprising a cellulosic derivative and an anionic emulsifying agent wherein the polymerizaton is initiated by an oil-soluble initiator and a water-soluble free radical polymerization initiator is added in the course of polymerization. The thus obtained polyvinyl chloride powders are particularly suitable for the production of battery separators.

Abstract: The invention relates to a process for the electrolytic production of hydrogen in an alkaline medium.The process consists in using a cathode, the active surface of which essentially consists of an oxide compound of the spinel type.The process is suitable, in particular, for the electrolysis of aqueous solutions of sodium chloride in cells with a permeable diaphragm.

Abstract: Process for the preparation of an aqueous suspension containing at least 65% by weight of calcium carbonate, in which process calcium carbonate is crystallized in a dilute aqueous medium, a wet concentrate of calcium carbonate is separated from the resulting dilute aqueous suspension of calcium carbonate and the said calcium carbonate concentrate is fluidized and homogenized in the presence of a dispersing agent. The calcium carbonate is crystallized in the presence of a water-soluble polyelectrolyte and the calcium carbonate concentrate is separated from the dilute suspension of calcium carbonate by essentially mechanical separating means.

Abstract: A process for the separation of polyolefins manufactured at low pressure with the aid of catalysts. Carbon monoxide is added to the reaction mixture resulting from the polymerization. The process makes it possible to obtain perfectly homogeneous polyolefins which can be used for the manufacture of films and fibers.

Abstract: A process is provided for dispersing finely divided water-insoluble particles in an aqueous medium. The dispersing agent used comprises a salt of a polymer derived from an alpha-hydroxyacrylic acid, which salt contains units of the formula ##STR1## wherein R.sub.1 and R.sub.2 independently represent hydrogen or an alkyl group containing 1 to 3 carbon atoms and wherein M represents a cationic radical resulting from the dissociation of a base.

Abstract: An electrode for the production of gas in an electrolytic cell of the membrane type with substantially vertical electrodes. The electrode is a substantially vertical conducting plate having a horizontal zone for connecting it to a current lead and is pierced by apertures for the evolution of a gas. Oblique vanes project from the plate opposite the apertures. The apertures are substantially vertically extending slots and the vanes are elongated extending from an active face of the electrode and are arranged adjacent the vertical slots.

Abstract: A hollow article made of an oriented thermoplastic having improved resistance to lateral impact, and provided with a base composed, successively, of a peripheral arched profile, a substantially plane annular zone and a recessed central part in the shape of a dome, the diameter of the central part being less than 40% of the maximum diameter of the hollow article. Such a hollow article is particularly suitable for the packaging of beverages.

Abstract: A process for the production of hollow articles from preforms of a thermoplastic material, one open end of which preforms has a neck moulded at least partially into its definitive shape. During the final blowing operation, the region corresponding to the moulded part of the preform is isolated from the remainder of the interior of the preform. The isolated region is cooled by sweeping with a cooling fluid.

Abstract: In the production of hollow bodies from a thermoplastic material, in which preforms are produced from thermoplastic material by molding, each resulting preform is transferred to a final blow-mold, and each preform is molded in a blow-mold to produce a desired final body, the production of each preform is carried out to provide the preform with a false neck having at least one positioning lug, and transfer of each preform to the blow-mold is carried out in such a manner as to cause the preform to have a predetermined angular position relative to the blow-mold by the action of its associated positioning lug.

Abstract: Process for the polymerization of .alpha.-olefins in the presence of an activator selected from among the organic compounds of metals of groups Ia, IIa, IIb and IIIa of the Periodic Table and a solid catalytic element prepared by(a) reducing TiCl.sub.4 by means of a reducing metal selected from among the metals of groups Ia, IIa, IIb, IIIa of the Periodic Table so as to prepare a double chloride of titanium and the reducing metal(b) treating the double chloride thus prepared by means of a complexant(c) reacting the double chloride thus treated with TiCl.sub.4(d) separating the solid catalytic element thus prepared.

Abstract: Solid catalytic complexes are useful for stereospecific polymerization of .alpha.-olefins to solid crystalline polymers. The complexes are formed by reducing TiCl.sub.4 with an alkylaluminum, treating thus-obtained reduced solid with a complexing agent and contacting the resultant with TiCl.sub.4. They have a specific surface greater than 75 m.sup.2 /g.

Abstract: Particles of titanium trichlorides usable for the stereospecific polymerization of alpha-olefines, especially propylene, having been dried until their liquid content is less than 1% by weight relative to the weight of titanium trichloride present in said particles, as well as a process for the preparation of such particles and a process for stereospecific polymerization in the presence thereof.

Abstract: Storage stability of Ziegler-type catalysts for .alpha.-olefin polymerization and having a specific surface greater than 75 m.sup.2 /g is improved by treating the catalysts with a preactivator which is an organic compound of a metal of one of Groups Ia, IIa, IIb and IIIa of the Periodic Table.CROSS-REFERENCE TO RELATED APPLICATIONThe invention described herein is directly related to that described in copending Application Ser. No. 236,407, filed Mar. 21st, 1972. The entire text of that application is incorporated herein by reference.BACKGROUND OF THE INVENTIONZiegler-type microporous catalytic complexes having a specific surface area greater than 75 m.sup.2 /g and useful for the polymerization of .alpha.-olefins are prepared by (a) reducing TiCl.sub.4 by means of an aluminum alkyl; (a') optionally isolating the reduced solid, based on TiCl.sub.

Abstract: Process for polymerizing in a reactor containing a polymerization mixture, and in aqueous suspension, a halogen-containing vinyl monomer, using a lipo-soluble initiator which generates free radicals, in the presence of an effective amount of an inhibitor of crust formation derived from a sulfur-containing organic compound, wherein the inhibitor of crust formation consists of anions derived from at least one arylsulfonic acid.

Abstract: Process for the separation of hydrogen fluoride from its mixtures with 1-chloro-1,1-difluoroethane, such as those obtained in the manufacture of the latter. An auxiliary solvent, chosen from among 1,1-dichloro-1-fluoroethane, vinylidene chloride, 1,1,1-trichloroethane and mixtures thereof, is added to the mixture so as to obtain two separate liquid phases, one of which contains the hydrogen fluoride and the other of which contains the 1-chloro-1,1-difluoroethane. Virtually all the hydrogen fluoride is recovered in the anhydrous form in the manufacture of monomers such as vinylidene fluoride, from chlorohydrocarbons such as vinylidene chloride and 1,1,1-trichloroethane.