Abstract: A multi-component article with controllable degradation and/or disintegration, comprising: a first part (A) which comprises at least one polyolefin combined with at least one prodegradation/prodisintegration agent; and; a second part (B) which comprises at least one polyolefin combined with at least one prodegradation/prodisintegration agent, provided that said first and said second parts differ at least by either one of type of polyolefin, type of prodegradation/prodisintegration agent and level of prodegradation/prodisintegration agent, the types of polyolefin and of prodegradation/prodisintegration agent and the levels of prodegradation/prodisintegration agent being selected so as said part (B) degrades more slowly than said part (A), and said part (B) at least partially covers said part (A).

Abstract: The invention relates to alkoxysilacycloalkanes, to the process of their preparation and to their use in the polymerization of olefins. The introduction of these alkoxysilacycloalkanes into the olefin polymerization environment makes it possible to raise the heptane-insolubles content of the polymer finally formed.

Abstract: This system consists of (A) at least one ligand (I) and (B) at least one nickel compound chosen from nickel complexes of zero oxidation state; &pgr;-allylnickels; and compounds of the bis(allyl)nickel type where E, E′=O, S; X, X′=P, As, Sb; R1, R′1=H, alkyl, aryl, arylalkyl, alkylaryl, halogen, OH, alkoxide where R′=a hydrocarbon radical of the C1-C15 type; —SO3Y where Y=Li, Na, NH4+, NR″4+ (R″=C1-C15 hydrocarbon radical); R2, R′2, R3, R′3, R4 and R′4=alkyl, arylalkyl; and R=divalent radical.

Abstract: A process is provided for preparing a catalyst support for polymerizing &agr;-olefins comprising the steps of: (i) reacting, in the presence of a first electron donor, a chlorine-containing organic compound and a prior mixture of an alkylmagnesien and an aluminoxane and/or aluminosiloxane and/or alkylaluminum and, optionally, a second electron donor; and (ii) activating a product from step (i) in suspension in an inert liquid by means of an activation electron donor, together with the support thus obtained, a catalyst for polymerizing &agr;-olefins, comprising this catalyst support and a group IV transition metal halide, and a process for polymerizing &agr;-olefins, particularly propylene, comprising contacting the &agr;-olefin with the catalyst.

Abstract: Activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that it consists of a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide, the said particles having been modified in order to carry, on the surface, aluminum and/or magnesium Lewis-acid sites of formula: groups coming from a functionalization agent having reacted with —OH radicals carried by the base particles of the support, the functionalization reaction having been followed by a fluorination reaction. The catalytic system according to the invention comprises (a) a metallocene catalyst, which has, if required, been subjected to a prealkylation treatment; (b) a cocatalyst; and (c) an activator solid support for metallocene, as defined above, it being possible for the cocatalyst (b) to be absent if the metallocene catalyst (a) has been prealkylated.

Abstract: The invention concerns a method for polymerising at least one olefin in the presence of at least a catalyst comprising a sequence E—M—X wherein E represents an oxygen or sulphur atom; M represents a nickel or palladium or platinum atom; X represents a phosphorus, arsenic or antimony atom in a medium comprising a continuous liquid phase containing more than 30 wt. % of water. The method can result in a polymer latex of at least one olefin.

Abstract: This process for preparing a catalyst support for the homopolymerization or copolymerization of ethylene and &agr;-olefins is characterized in that at least one organochlorine compound and a premix of at least one alkylmagnesium and of at least one organoaluminum compound chosen from aluminoxanes, aluminosiloxanes and alkylaluminums are reacted together, in the presence of at least one aliphatic diether as electron donor.

Abstract: The invention relates to alkoxysilacycloalkanes, to the process of their preparation and to their use in the polymerization of olefins. The introduction of these alkoxysilacycloalkanes into the olefin polymerization environment makes it possible to raise the heptane-insolubles content of the polymer finally formed.

Abstract: Activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that it consists of a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide, the said particles having been modified in order to carry, on the surface, aluminium and/or magnesium Lewis-acid sites of formula: 1

Abstract: The invention relates to alkoxysilacycloalkanes, to the process of their preparation and to their use in the polymerization of olefins. The introduction of these alkoxysilacycloalkanes into the olefin polymerization environment makes it possible to raise the heptane-insolubles content of the polymer finally formed.

Abstract: Activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that it consists of a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide, the said particles having been modified in order to carry, on the surface, aluminium and/or magnesium Lewis-acid sites of formula: or —Mg—F, the groups coming from a functionalization agent having reacted with —OH radicals carried by the base particles of the support, the functionalization reaction having been followed by a fluorination reaction. The catalytic system according to the invention comprises (a) a metallocene catalyst, which has, if required, been subjected to a prealkylation treatment; (b) a cocatalyst; and (c) an activator solid support for metallocene, as defined above, it being possible for the cocatalyst (b) to be absent if the metallocene catalyst (a) has been prealkylated.

Abstract: A process is provided for preparing a catalyst support for polymerizing &agr;-olefins comprising the steps of: (i) reacting, in the presence of a first electron donor, a chlorine-containing organic compound and a prior mixture of an alkylmagnesien and an aluminoxane and/or aluminosiloxane and/or alkylaluminum and, optionally, a second electron donor; and (ii) activating a product from step (i) in suspension in an inert liquid by means of an activation electron donor, together with the support thus obtained, a catalyst for polymerizing &agr;-olefins, comprising this catalyst support and a group IV transition metal halide, and a process for polymerizing &agr;-olefins, particularly propylene, comprising contacting the &agr;-olefin with the catalyst.

Abstract: A process is provided for preparing a catalyst support for polymerizing &agr;-olefins comprising the steps of: (i) reacting, in the presence of a first electron donor, a chlorine-containing organic compound and a prior mixture of an alkylmagnesien and an aluminoxane and/or aluminosiloxane and/or alkylaluminum and, optionally, a second electron donor; and (ii) activating a product from step (i) in suspension in an inert liquid by means of an activation electron donor, together with the support thus obtained, a catalyst for polymerizing &agr;-olefins, comprising this catalyst support and a group IV transition metal halide, and a process for polymerizing &agr;-olefins, particularly propylene, comprising contacting the &agr;-olefin with the catalyst.

Abstract: The invention relates to alkoxysilacycloalkanes, to the process of their preparation and to their use in the polymerization of olefins. The introduction of these alkoxysilacycloalkanes into the olefin polymerization environment makes it possible to raise the heptane-insolubles content of the polymer finally formed.

Abstract: Activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that it consists of a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide, the said particles having been modified in order to carry, on the surface, aluminium and/or magnesium Lewis-acid sites of formula: functionalization agent having reacted with —OH radicals carried by the base particles of the support, the functionalization reaction having been followed by a fluorination reaction. Also disclosed is a catalytic system including a metallocene catalyst, which has optionally been subjected to a prealkylation treatment; a cocatalyst; and an activator solid support for metallocene, as defined above.

Abstract: The invention relates to a process for the preparation of a solid catalytic component of metallocene type for the polymerization of olefins comprising a stage of reaction between a support and a derivative of formula R.sup.1 M.sup.1 X.sup.1.sub.3, in which R.sup.1 represents a hydrocarbon radical, M.sup.1 represents a silicon, germanium or tin atom and X.sup.1 represents a halogen atom. The solid catalytic component according to the invention exhibits a high activity in the polymerization or copolymerization of olefins and can lead to polymers or copolymers of high molecular mass and of low polydispersity, for example less than 2.5.