Abstract: Composition based on a crosslinkable polyethylene comprising from 0.05 to 0.24 hydrolysable silane groups per 100 —CH2— units and having a standard density SD of at least 954 kg/m3 and a melt flow index MI5 of less than 1.5 g/10 min. Pipes for the transportation of fluids under pressure, which can be obtained by extruding this composition and then hydrolysing it.

Abstract: A stabilized polypropylene composition, free or essentially free of any phenolic antioxidant containing: a) 100 parts by weight of a propylene polymer, b) from 0.005 to 0.1 part by weight of an amine oxide having the structural formula wherein R? and R? are groups containing from 1 to 36 carbon atoms, or of a N,N-dialkylhydroxylamine of formula R1R2NOH??(II) wherein R1 and R2 are independent groups of 1 to 36 carbon atoms, c) from 0.1 to 0.5 part by weight of a clarifying agent, and optionally d) from 0.01 to 0.1 part by weight of a sterically hindered amine. Manufacture of shaped object by using said composition and manufactured objects so obtained.

Abstract: Compositions comprising one or more olefin polymers functionalized by at least one functionalization agent chosen from carboxylic acids, their esters, their anhydrides and their metal salts and one or more stabilizing agents comprising one or more sterically hindered phenol groups and at most one ester functional group. Process for their preparation and use of these compositions for compatibilizing olefin polymers with polymers, fillers and metal substrates which are incompatible with olefin polymers.

Abstract: A complex of a transition metal complying with the general formula (I) in which M is a transition metal of groups 6 to 12, T is the oxidation state of M, each A, which may be identical with or differ from each other, is an atom or an atomic grouping bonded covalently or ionically to the transition metal M, b is the valency of A, each R1, R2, R3, R4 and R5 is independently a hydrogen atom, an unsubstituted or substituted hydrocarbon group, an unsubstituted or substituted heterohydrocarbon group, or an inert functional group, R6 and R7 are, independently of one another, a polynuclear aromatic hydrocarbon group containing at least two condensed benzene nuclei, substituted with at least one hydrocarbon group.

Abstract: Continuous process for manufacturing a polyolefin resin in at least two polymerization reactors connected in series, in which the polymer suspensions leaving the reactors are transferred into hydrocyclone separators in which a flow comprising diluent and polymer particles, on the one hand, and a concentrated suspension of polymer particles, on the other hand, are formed and separated. The flows comprising the polymer particles are recycled into the first polymerization reactor.

Abstract: A device for purging a high-output polymer extruder includes a purge valve for discharging a molten polymer from the extruder. A cutting device is arranged at the output of this purge valve so as to be able to cut a continuous stream of polymer at the output of the purge valve into blocks. A conveying device, preferably hydraulic, is arranged at the output of the cutting device, so as to transport the blocks in a flow of liquid and convey them away from the discharge zone of the purge valve. The hydraulic conveying device preferably includes a chute equipped with a liquid-injection device, and a channel equipped with a device for creating a strong flow of liquid in the channel.

Abstract: Process for manufacturing an olefin polymer composition in at least two polymerization reactors connected in series, in which the suspension of polymer in a diluant, formed in the first reactor, is sent into a hydrocyclone seperator in which, on the one hand, a stream comprising diluant and, on the other hand, a concentrated suspension of polymer particles are formed and separated. The concentrated suspension is then introduced into the subsequent polymerization reactor.

Abstract: Process for the preparation of a catalytic system according to which a mixture of a halogenated neutral metallocene derived from a transition metal chosen from groups IIIB, IVB, VB and VIB of the Periodic Table and of an organoaluminium compound is prepared and an ionising agent is added thereto. (Co)polymerisation process according to which a mixture of a halogenated neutral metallocene as defined above and of an organoaluminium compound is prepared, the olefin is brought into contact with this mixture and an ionising agent is added thereto.

Abstract: Process for polymerizing alpha-olefins, in which at least one alpha-olefin is placed in contact, under polymerizing conditions, with a catalytic system comprising (a) a solid catalyst comprising (i) a compound of a transition metal from groups 4 to 6 of the Periodic Table, containing at least one cyclopentadiene ligand which may be substituted, (ii) an activator chosen from aluminoxanes and ionizing agents, and (iii) a porous polymeric support, and (b) at least one organoaluminium compound corresponding to the general formula R3−nAl(Y′)n in which 0.

Abstract: Process for manufacturing olefin polymers, in which some of the suspension of olefin polymer particles formed in a diluent is drawn off from the polymerization reactor and diluted by means of a liquid before being sent into a hydrocyclone separator in which, on the one hand, a concentrated suspension of polymer particles and, on the other hand, a stream essentially comprising diluent are formed and separated.

Abstract: Novel silylene or ethylene bis(tetrahydrofluorenyl)metallocenes are synthesized and used as olefin polymerization catalysts.

Abstract: The olefin polymerization catalyst comprises a supported transition metal, magnesium and halogen; the support comprises aluminum phosphate and at least one oxide of silica or alumina. The catalyst is formed by impregnating the support with a liquid complex formed by reacting a magnesium compound and a transition metal compound, which can contain either oxygen or halogen, and then precipitating the complex on the support with an organoaluminum compound which may be halogenated. The catalyst is used with an organometallic cocatalyst.

Abstract: Process for the preparation of a catalyst for the polymerization of alpha-olefins involves contacting a porous polyolefin support with a solution containing an activator (ii) to form a suspension. The suspension is evaporated in a reactor fitted with a stirrer comprising a scraping element. The scraping element follows the walls of the reactor at a distance from 2 to 200 times the mean particle diameter of the support. The catalyst includes a compound of a transition metal (i) from Groups 4 to 6 of the Periodic Table and at least one optionally substituted cyclopentadiene ligand and an aluminoxane activator (ii). The aluminoxane activator (ii) and transition metal compound are supported on the porous polyethylene support (iii). The walls of the reactor show no traces of crusting.

Abstract: A continuous process for obtaining propylene polymers in the presence of a catalytic system of the Ziegler-Natta type containing a catalytic solid comprising chlorine, magnesium and titanium atoms and at least one electron-donor compound, called internal donor, a cocatalyst which is an organoaluminium compound, and optionally an electron-donor compound, called external donor, comprising the following successive stages: (a) polymerization of propylene in liquid propylene to form, per g of titanium in the catalytic solid, from 11000 to 28000 g of a prepolymer chosen from among the homopolymers of propylene, and (b) gas-phase polymerization of propylene in one or more successive fluidized-bed reactors and in the presence of the prepolymer (a), of propylene, optionally in the presence of one or more other monomers chosen from among the &agr;-olefins containing from 2 to 12 carbon atoms to produce a final propylene polymer whose fraction of particles of diameter smaller than 125 &mgr;m (FP) is at most 10 wt %.

Abstract: Continuous process for manufacturing a polyolefin resin in at least two polymerization reactors connected in series, in which the polymer suspensions leaving the reactors are transferred into hydrocyclone separators in which a flow comprising diluent and polymer particles, on the one hand, and a concentrated suspension of polymer particles, on the other hand, are formed and separated. The flows comprising the polymer particles are recycled into the first polymerization reactor.

Abstract: Process for manufacturing olefin polymers, in which some of the suspension of olefin polymer particles formed in a diluant is drawn off from the polymerization reactor and diluted by means of a liquid before being sent into a hydrocyclone separator in which, on the one hand, a concentrated suspension of polymer particles and, on the other hand, a stream essentially comprising diluant are formed and separated.

Abstract: Process for manufacturing an olefin polymer composition in at least two polymerization reactors connected in series, in which the suspension of polymer in a diluant, formed in the first reactor, is sent into a hydrocyclone seperator in which, on the one hand, a stream comprising diluant and, on the other hand, a concentrated suspension of polymer particles are formed and separated. The concentrated suspension is then introduced into the subsequent polymerization reactor.

Abstract: Process for the manufacture of a composition comprising ethylene polymers, in at least two polymerization reactors connected in series, according to which, in a first reactor, from 30 to 70% by weight with respect to the total weight of the composition of an ethylene homopolymer (A) having a melt flow index MI2 of 5 to 1000 g/10 min is formed and, in a subsequent reactor, from 30 to 70% by weight with respect to the total weight of the composition of a copolymer of ethylene and of hexene (B) having a melt flow index MI5 of 0.01 to 2 g/10 min is formed. The compositions obtained by this process exhibit a good compromise between the processing properties and the mechanical properties, which renders them capable of being used in the manufacture of articles shaped by extrusion and extrusion blow-molding, such as films and pipes.

Abstract: A propylene block copolymer comprising(A) 60-90 weight %, based on the total amount of the block copolymer, of a first block of a propylene polymer, optionally containing a small amount of copolymerised ethylene,(B) 40-10 weight %, based on the total amount of the block copolymer, of a second block of an ethylene-propylene copolymer containing 1-10 weight % of ethylene, and the total ethylene content of the block copolymer being within the range of 0.1-2.5%. The weight process for the manufacturing of the propylene block copolymer and use of it for the manufacture of bioriented bottles.

Abstract: A control method for a process of synthesis of at least one chemical product in an equipment comprising at least one reactor (R) which is assimilated to a mixed reactor, in which manipulated variables (GC) allow to act on the course of the process in order to make one or more variables related to the properties of the product and/or to the running of the process, which are called controlled variables (GR).