摘要:
The invention concerns a method for making acrylonitrile fibers. More particularly, it concerns a method for making acrylonitrile fibers characterized in that it is carried out in the presence of at least an azocarboxylic acid ester.
摘要:
The present invention relates to offshore flexible pipes in which the sealing layers comprise, in this order: an inner layer formed from at least one thermoplastic polymer (A); optionally, a coextrusion tie layer; and a polyolefin layer. According to another embodiment of the invention, the sealing layers comprise, in this order: an inner layer formed from at least one thermoplastic polymer (A); optionally, a coextrusion tie layer; a polyolefin layer; optionally, a coextrusion tie layer; an outer layer formed from at least one thermoplastic polymer (B). The invention also relates to flexible pipes comprising these sealing layers. The invention also relates to the use of these flexible pipes for transporting fluids in offshore oil and gas extraction fields.
摘要:
The present invention relates to a flexible and tough composition comprising: at least one vinylidene fluoride (VF2) homopolymer (A) or a copolymer (A) of VF2 and at least one other monomer copolymerizable with VF2, in which the said monomer is present in an amount of between 0 and 30 parts by weight per 100 parts by weight of VF2, at least one fluoroelastomer B, optionally a plasticizer C, in which, on the one hand, the said composition comprises from 0.5 to 10 parts by weight of B and from 0 to 10 parts by weight of C per 100 parts by weight of A, with the additional condition that the sum of B and C is from 0.5 to 10.5 parts by weight and, on the other hand, the vinylidene fluoride homopolymer or copolymer (A) is chosen in such a way that it has a melt flow index, measured according to the ISO 1133 standard at 230null C. under a load of 5 kg, of less than 5 g/10 min and a critical modulus GC, at the intersection of the melt shear moduli Gnull and Gnull measured at 190null C., of between 5 and 22 kPa. This composition is especially used for the manufacture of pipes for conveying hydrocarbons extracted from off-shore or on-shore oil deposits.
摘要:
A metal surface is coated with a coating comprising, in succession starting from the metal: optionally, a primer layer; optionally, a tie layer; and a polyamide-based layer consisting of a blend of a polyamide and of a polyolefin functionalized by an unsaturated carboxylic acid anhydride. Advantageously, the metal surface is the outer surface of a tube, particularly a small-diameter pipe having, for example, an outside diameter of 4 to 50 mm. The metal may be any metal, but the coating is very useful for steel and its alloys and for aluminium and its alloys. The optionally, a tie layer; aluminium may be anodized. Thus, the coated surface can comprise aluminium, the anodizing layer, the optional primer, the optional tie and the PA-based layer. The steel may be coated with zinc or a Zn-based alloy (such as, for example, a ZnnullAl or ZnnullFe mixture) or with aluminium or an Al-based alloy and/or treated by chromatizing or phosphatizing. Thus, the coated surface can comprise steel, the optional zinc or aluminium layer, the optional chromatizing or phosphatizing treatment layer, the optional primer, the optional tie and the PA-based layer. Preferably, the chromatizing is carried out with CrIII.
摘要:
The present invention relates to a composite material comprising, by weight, the total being 100% : A) 40 to 90% of PVDF homopolymer or copolymer crystallized essentially in the null form, B) 10 to 60% of a conductive filler, C) 0 to 40% of a crystalline or semi-crystalline polymer, D) 0 to 40% of a filler other than C, such that the crystals in the null form are nucleated on the surface of the particles of the conductive filler. This material is conductive with a resistance which is self-regulated by the temperature. It shows an increase in the resistance as a function of the temperature (PTC or nullPositive Temperature Coefficientnull effect), so that the intensity stabilizes at an equilibrium temperature.
摘要:
Foam blowing agent blends of trans-1,2-dichloroethylene and one or more pentanes are provided, as are polyol premixes and foam compositions containing such blends. The resulting foams exhibit dramatic improvement in fire resistance.
摘要:
Butyl acrylate is prepared by reacting acrylic acid and butanol in a reactor in the presence of an esterification catalyst the water formed being entrained by distillation in a column (2) in the form of a heteroazeotropic mixture with butanol mixture following condensation, being separated in a decanter (3) to give an upper, organic phase which is recycled to the top of the distillation column (2) and a lower, aqueous phase which is drawn off. The reaction is conducted with deferred introduction of part of the butanol at the top of the distillation column (2) or to the decanter (3) or to the reactor (1), the butanol/acrylic acid molar ratio being initially between 0.5 and 1 before rising to between 1 and 1.5 following the completion of the deferred introduction of the butanol.
摘要:
The invention relates to a process for trapping a free monomer which has not reacted by copolymerization or by grafting comprising at least one epoxide functional group in a thermoplastic composition based on ethylene and/or on propylene and based on at least one monomer comprising at least one epoxide functional group, the said process comprising the following stages: preparation of the said thermoplastic composition, addition of a sufficient amount of a solid trapping additive exhibiting, at its surface, sites with a basic nature within the Lewis or Brnullnsted meaning. The trapping additive is a porous zeolite, the diameter of the pores of which is between 5 and 15 angrstrnullms, preferably between 6 and 13 angrstrnullms. The invention also relates to the composition obtained by such a process and to the blends comprising such a composition.
摘要:
The invention relates to a method for preparing bromodifluoroacetic compounds which comprises converting a 1,1-diflouro-1,2-dibromodihaloethane with oleum having 50-70% SO3 to a bromodifluoroacetyl halide (bromide or chloride) and then in reacting the latter directly with either an alcohol, or with water.
摘要:
A compound of formula (I) is prepared alone or in combination with at least one monomer of formula (II): the quaternizing agents benzyl chloride is introduced into a solution, in a solvent selected from compounds of the formulae (I) and (II) and mixtures of these, of the compound of formula (III) at a temperature of from 35 to 60null C., and then water is added and the reaction is allowed to proceed to complete or substantially complete conversion of the compound (III), an aqueous solution of desired compound (I) is isolated where appropriate with at least one compound (II), if this or these have/has been used as solvent, and the water is removed where appropriate. 1