Abstract: In order to manufacture pentafluoroethane (F125) and/or 1,1,1,2,3,3,3-haptafluoropropane (F227ea), a trifluoromethane gas stream is subjected to pyrolysis and then the mixture of gases which result from this pyrolysis is brought into contact with a fluorination catalyst.

Abstract: To avoid the formation of acidity in an F125 containing olefins, a radical scavenger and/or an acidity scavenger is added to it.

Abstract: The invention relates to a mixture in powder form and comprising (i) at least one polyamide and (ii) at least one polymer (A) containing hydroxyl functional groups and compatible with the polyamide. The polymer (A) may be an ethylene/vinyl alcohol copolymer. The mixture may be used to coat metal substrates.

Abstract: In order to remove olefinic impurities present in a hydrofluorocarbon such as pentafluoroethane (R-125), the impure hydrofluorocarbon is treated with oxygen in the absence of catalyst or of active charcoal.The process is well suited to the purification of fluoroethanes and, more particularly, to that of pentafluoroethane.

Abstract: Polyetheresteramides, characterized in that they comprise both of the following repeating entities: ##STR1## in which X represents the residue of a polyamide-diacid oligomer with an Mn of between 300 and 8000, Y represents the residue of a polyetherdiol with an Mn of between 200 and 5000, and Z represents the residue of a polyetherdiamine with an Mn of between 200 and 5000, wherein the proportion by mass of the entities Z resulting from the condensation of the polyetherdiamine with respect to the total amount of the entities resulting from the polyetherdiol and polyetherdiamine, i.e. Z/(Z+Y), is between 1 and 50%. The polyetheresteramides according to the invention can be used as is and are suitable for the production of mouldings, extrudates, films, sheaths, or composite materials such as multi-layer film. They can also be mixed with other polymers and in particular with polyamides.

Abstract: The present invention provides block copolymers of the formula: ##STR1## in which R represents an aliphatic residue, A an aromatic residue, x is such that the inherent viscosity (measured in methanesulphonic acid at a concentration of 0.2 g per deciliter at 30.degree. C.) in deciliters per gram is greater than 0.6, and n and n' are greater than or equal to 2. These polymers are made from two different diacids and have two glass transition temperatures, with one glass transition temperature being between -50.degree. and +50.degree. C. and the other glass transition temperature being between 180.degree. and 300.degree. C.

Abstract: The present invention relates to new polyamides comprising, on a mass basis:(a) 45 to 75% of an x,T unit, x being between 4 and 12 inclusive, the x,T unit being the condensation product of a diamine having x carbon atoms and of terephthalic acid, and(b) 55 to 25% of an aliphatic unit -HN-(CH.sub.2).sub.n -CO, n being between 6 and 14 inclusive. and the terpolyamides obtained by including a monomeric unit (c) such as the unit 6 or 6,I as a replacement for part of the aliphatic unit (b).The polyamide compositions thus obtained exhibit a Tg lower than 130.degree. C., a Tm higher than 230.degree. C. and a good crystallizability.

Abstract: Copolyamides having high crystallinity over the whole composition range, a melting enthalpy .DELTA.H>3.5 cal/g and a melting point T.sub.M higher than 270.degree. C. and articles manufactured therefrom are disclosed, said copolyamides comprising, by moles:a) 1 to 99% of a unit A of formula--(NH--R--NHCO--AR.sub.1 --CO)--in which R is a --(CH.sub.2).sub.n --carbon chain where n is coma) between 4 and 20, and AR.sub.1 is the residue from the condensation of terephthalic acid and/or of the diester form thereof; andb) 99 to 1% of a unit B of formula--(NH--R--NHCO--AR.sub.2 --CO)--in which R is the same carbon chain as in unit A and AR.sub.2 is the residue from condensation of naphthalene-2,6-dicarboxylic acid and/or the diester form thereof.

Abstract: A process for the manufacture of polyamides consisting essentially of the stages of:(i) reacting 10 to 90% by weight of the aliphatic and/or cycloaliphatic and/or aromatic-aliphatic diamines (c) with a lactam and/or corresponding amino acid (a) or the substantially stoichiometric combination of one or more aliphatic diamine(s) and of one or more dicarboxylic aliphatic acid(s) and with the aromatic diacid (b); and(ii) reacting the remainder of the aliphatic and/or cycloaliphatic and/or aromatic-aliphatic diamine (c) with the oligomer produced in stage (i) in one or more substages.