Abstract: A portion of a plastic tube (16) heated to a temperature at which stretching induces a molecular orientation, is clamped in a sleeve (14), a fluid under pressure is introduced into the portion of tube and the sleeve is moved along the portion of tube to cause its progressive radial expansion until it makes contact with a mould (1).

Abstract: Permeable diaphragm for a cell for the electrolysis of aqueous solutions of an alkali metal halide, the diaphragm being made from a hydrophobic organic polymeric material containing an oxide of a metal chosen from amongst group IIa of the periodic table of the elements, the oxide being in the form of particles having a mean diameter of at most 0.5 .mu.m.

Abstract: The film (11) extruded from a vinylidene fluoride polymer is subjected to a stretching of at least 200% while still in the molten state, and then cooled rapidly to a temperature below 50.degree. C.The equipment comprises, in series, an extruding device (1) (2), a cooling device consisting of a thermostatically controlled liquid bath (6), the level of which is located at a distance of 10 to 300 mm from the extruding device, and a device (8) (9) for stretching the extruded film by at least 200% in its part located between the extruding device and the cooling device.The film obtained is suitable for manufacturing piezoelectric films.

Abstract: The preform (1) for the production of hollow articles by blow-moulding possesses a profiled false neck (4) provided with a circular toothed collar (6), and during the thermal conditioning of the preform for the purpose of final blowing, the preform, held loosely by idling holding rollers (8)(9) at the level of the profiling of its false neck (4), is caused to rotate about its longitudinal axis by a toothed drive member (13) which cooperates with the circular toothed collar (6).

Abstract: The preform (1) for the production of hollow articles by blow-moulding possesses a profiled false neck (4) provided with a circular toothed collar (6), and during the thermal conditioning of the preform for the purpose of final blowing, the preform, held loosely by idling holding rollers (8) (9) at the level of the profiling of its false neck (4), is caused to rotate about its longitudinal axis by a toothed drive member (13) which cooperates with the circular toothed collar (6).

Abstract: A process for the production of polypropylene fibrids of short length by abrupt expansion of a liquid mixture of molten polypropylene, an alkane solvent for the polypropylene, and a minor amount of a non-solvent for the polypropylene. The mixture, which is at a high temperature and high pressure, is ejected through an expansion orifice to instantaneously vaporize the alkane and to solidify the polypropylene.

Abstract: Process and plant for the preparation of concentrated aqueous solutions of alkali metal hypochlorite, in which a suspension of crystals of alkali metal chloride in an aqueous solution of alkali metal hypochlorite is circulated from bottom to top in a tubular reaction chamber located in an enclosure, chlorine and an aqueous solution of alkali metal hydroxide are reacted in this suspension in the chamber, a fraction of the resulting suspension leaving the open upper part of the chamber, overflows out of the enclosure and is filtered to separate the crystals, and the remaining fraction of the suspension is kept in the enclosure where it is recycled to the base of the reaction chamber.

Abstract: Moulding composition comprising a vinylidene fluoride polymer and a blowing agent which is a hydroxycarboxylic acid or an alkali metal salt derived from one of the acids.

Abstract: A process for the manufacture of olefine oxides, comprising reacting, with an olefine, an organic solution of percarboxylic acid which is obtained by reacting the corresponding carboxylic acid with hydrogen peroxide. The organic solvent employed is a mixture of inert organic solvents which does not form an azeotrope with the olefine to be epoxidized or with the olefine oxide, and which contains a volatile solvent, the boiling point of which is lower than that of the olefine oxide, and a solvent of low volatility, the boiling point of which is higher than that of the olefine oxide.

Abstract: Vinyl chloride and any other comonomers present in a vinyl chloride polymer are removed by heating the polymer to a temperature between its glass transition temperature and 180.degree. C. by directly condensing steam on to the polymer, maintaining the polymer at this temperature sufficiently long to remove the greater part of the monomer or monomers present in the polymer and then cooling the polymer to below its glass transition temperature by evaporating the steam that has condensed on the polymer.

Abstract: The invention relates to a composite panel comprising at least one metal foil combined, by hot pressing, with at least one polyolefine sheet in which the polyolefine sheet is produced from a mixture of 10 to 90% by weight of cellulose fibres and from 90 to 10% by weight of a polyolefine modified by polar monomer units derived from at least one monomer selected from the group consisting of the unsaturated carboxylic acids, the corresponding anhydrides and their derivatives. The presence of cellulose fibres in the polyolefine improves the adhesion between the components of the composite panel.

Abstract: The invention relates to a process for inhibiting the corrosion of an installation, made of a material chosen from amongst the metals which are less noble than hydrogen, and their alloys, in contact with an acid bath containing an alkylpyridinium chloride.A soluble cyanide complex, which is capable of forming an insoluble compound by reacting with ferric ions in the bath, is added to the bath so as to limit the concentration of the ferric ions in the bath to a maximum of 30 mg/kg. The content of ferric ions in the bath is controlled by means of a potentiometric measurement so as to bring the potential of the bath into the region of a predetermined value.The invention applies in particular to the treatment of baths for cleaning or descaling steel installations.

Abstract: The invention relates to a cathode for the electrolytic production of hydrogen.The cathode comprises an active surface consisting of a metal oxide obtained by the thermal decomposition of a thermally decomposable compound of a metal chosen from amongst cobalt, iron, manganese or nickel.The cathode is particularly suitable for the electrolysis of aqueous sodium chloride solutions in cells with a permeable diaphragm.

Abstract: The invention relates to compositions of chlorinated solvents such as 1,1,1-trichloroethane, stabilized by means of a heterocyclic compound containing oxaziridine units, such as 2-tert.-butyloxaziridine.

Abstract: Particles of alloys of a noble metal chosen from among iridium, osmium, palladium, platinum, rhodium and ruthenium, hereafter represented by M, with at least one non-noble metal chosen among silver, bismuth, cadmium, cobalt, copper, tin, germanium, indium, manganese, mercury, molybdenum, nickel, gold, lead, rhenium, thallium, tellurium, technetium, tungsten, vanadium and zinc, hereafter referred to as Me', and Me', representing at least one non-noble metal, characterized in that they correspond to the general formulaM.sub.n Me'.sub.mwhere n represents an integer equal to 1, 2 or 3 and where m represents an integer equal to 1, 2 or 3, and in that their specific surface area is between 0.5 and 800 m.sup.2 /g of alloy and in that the mean diameter of the alloy particles is between 10 and 10,000 A.The particles are prepared by reducing the mixed oxides of the corresponding formulaM.sub.n Me'.sub.m O.sub.xThey are used as catalyst for dehydrogenation or hydrogenation.

Abstract: A process for the manufacture of shaped articles from compositions containing 30 to 70% by weight of polyolefine which is a high density polyethylene modified with polar monomers and 30 to 70% by weight of cellulosic fibres. These compositions are malaxated at a temperature at least 20.degree. C. above the melting point of the polyolefine. The process is applicable to the manufacture of panels which can be used in the automobile industry.

Abstract: Process for rapidly terminating the polymerization of vinyl chloride in aqueous suspension in the presence of lower dialkyl peroxydicarbonates by introducing effective amounts of ammonium hydroxide and an alkali metal thiosulphate, e.g. sodium or ammonium thiosulphate, into the polymerization medium. This process enables polymerization to be quickly and effectively terminated when a breakdown occurs.

Abstract: In the manufacture of oriented hollow articles made of thermoplastic material by the steps of extruding a continuous hot tubular parison of thermoplastic material; pre-blowing such parison in a pre-blowing mold to produce preforms having a cylindrical body with a diameter not more than 20% greater than that of the parison; thermally conditioning the resulting preforms at a temperature sufficient to cause orientation of the thermoplastic material when it is being stretched; and effecting a final blow-molding of the thermally conditioned preforms, the mechanical properties of the resulting articles in the vicinity of their base are improved by carrying out the pre-blowing step while holding each parison tightly between two half-molds defining a cavity which has the shape, at the location of the base of the preform, of a quarter sphere of diameter equal to that of the preform, and cutting off the resulting flash by means of an elongated blade having a semi-circular cross section and a diameter corresponding to t

Abstract: Poly-.beta.-hydroxybutyrates obtained by biosynthesis are hydrolyzed in a reaction mixture containing poly-.beta.-hydroxybutyrates, water and an acid catalyst, in a solvent.

Abstract: Process for stabilizing solutions of peroxidic compounds used for bleaching. At least one polymer derived from an alpha-hydroxyacrylic acid, which contains units of the formula ##STR1## where R.sub.1 and R.sub.2 represent hydrogen or an alkyl group comprising from 1 to 3 carbon atoms which can be substituted by a hydroxyl group or a halogen atom, R.sub.1 and R.sub.2 being identical or different, and where M represents an alkali metal atom, a hydrogen atom or an ammonium group, is added to the solution as a stabilizer.