Abstract: (I) The (co)polymerisation of ethylene is carried out in at least one reaction zone (R) under high pressure, at 150.degree.-320.degree. C.; (II) the reaction product is routed into a zone (S), under an intermediate pressure P, for separation of the (co)polymer, in the molten state, from the unreacted (co)monomer(s), or the reaction product is routed into a first separation zone (S1), under an intermediate pressure (P1); the (co)polymer issuing from (S1) is then routed into a second separation zone (S2), under a pressure P2<P1; (III) the (co)polymer is routed into a zone (SF), under low pressure, for final separation of the (co)polymer from the residual gases. Let-down zones (D), (D1) and (D2) are provided along the path of the (co)polymer between the zones (S) and (SF), (S1) and (S2), and (S2) and (SF) respectively, the grafting monomer or monomers being introduced on-line, in the path of the (co)polymer, at at least one point located at the level of the zone (D) or at at least one zone (D1, D2).

Abstract: The compositions contain a) less than 90% and at least 2% by weight of at least one ethylene polymer (A), and optionally, at least one .alpha.-olefin having from 3 to 12 carbon atoms, said polymer containing at least 70% in moles of patterns derived from ethylene, and b) more than 10% and up to 98% by weight of at least one polymer (B) containing at least 85% in moles of patterns derived from at least one .alpha.-olefin having from 3 to 12 carbon atoms and at the most 15% in moles of patterns derived from ethylene, and are characterized in that the polymer (A) is a modified polymer of which the measured limit viscosity is comprised between 1.3 and 100 times its limit viscosity calculated from the distribution of molecular masses. The compositions are obtained by a process consisting in providing a polymer of ethylene and, optionally, of at least one .alpha.-olefin having from 3 to 12 carbon atoms in the presence, on the one hand, of at least one initiator of free radicals in a quantity comprised between 0.

Abstract: The compositions contain a) less than 90% and at least 2% by weight of at least one ethylene polymer (A), and optionally, at least one .alpha.-olefin having from 3 to 12 carbon atoms, said polymer containing at least 70% in moles of patterns derived from ethylene, and b) more than 10% and up to 98% by weight of at least one polymer (B) containing at least 85% in moles of patterns derived from at least one .alpha.-olefin having from 3 to 12 carbon atoms and at the most 15% in moles of patterns derived from ethylene, and are characterized in that the polymer (A) is a modified polymer of which the measured limit viscosity is comprised between 1.3 and 100 times its limit viscosity calculated from the distribution of molecular masses. The compositions are obtained by a process consisting in providing a polymer of ethylene and, optionally, of at least one .alpha.

Abstract: The compositions contain:(a) from 90 to 99.8% by weight of at least one modified polymer of ethylene and, where appropriate, at least one .alpha.-olefin having from 3 to 12 carbon atoms, the said polymer containing at least 80 mol % of units derived from ethylene, and(b) from 0.2 to 10% by weight of at least one polymer phase (B) comprising at least one polymer containing at least 90 mol % of units derived from at least one .alpha.-olefin having from 3 to 12 carbon atoms, and at most 10 mol % of units derived from ethylene,the said compositions having a measured limiting viscosity of between 1.5 and 100 times their limiting viscosity calculated from the distribution of the molecular masses.The process for preparing them consists in modifying a polymer (A) containing at least 80 mol % of units derived from ethylene and at most 20 mol % of units derived from at least one .alpha.

Abstract: Process and device for cooling a tubular sleeve produced by hot extrusion-blowing of a thermoplastic material through an annular die. In the process, a stream of primary air is flowed under pressure substantially parallel to and spaced from the tubular sleeve and reaches the tubular sleeve at a second stage. The stream of primary air induces a stream of secondary air which flows substantially parallel and proximate to the tubular sleeve at a first stage and whose flow is substantially laminar over most of its path. The device includes a first cylindrical sleeve member that, in combination with the tubular sleeve, defines a secondary air flow space. A second cyclindrical sleeve member and the first sleeve member define a primary air flow space therebetween. A cylindrical ring disposed proximate to the annular die directs air into the secondary air flow space. A source of pressurized air is in flow communication with the primary air flow space.

Abstract: Apparatus for cooling plastic film or sheet obtained by blowing tubing, comprising at its intermediate section an intensive blowing ring for directing air towards the tubing and at its upper section an upper chamber in which the tubing is in contact with an air flow directed in the drawing direction of the tubing. At the lower section of the apparatus is a non-closed lower chamber provided with at least one opening. The apparatus can be used to form blown films having superior optical properties, particularly clarity and turbidity, from a large number of resins.

Abstract: A process for the manufacture of radical ethylene terpolymers or copolymers comprising moieties derived from an alkyl (meth)acrylate and/or moieties derived from maleic anhydride by copolymerizing, in the presence of at least one free-radical initiator, a mixture of ethylene, (meth)acrylate and/or maleic anhydride in a device incorporating a primary compressor, the delivery pressure of which is between 200 and 300 bars, connected to a secondary compressor which is connected directly to a polymerization reactor, fresh ethylene being fed at the intake of the said primary compressor and said copolymerization being carried out in the said polymerization reactor under a pressure of between 1,000 and 2,500 bars and a temperature of between 140.degree. and 280.degree. C., wherein at least one the alkyl (meth)acrylate and/or maleic anhydride is fed directly into the said polymerization reactor.