Abstract: Thermally stable compositions, also showing high fluidity in the molten state comprise polyphenylene oxide, or a mixture of polyphenylene oxide with a styrene polymer, and a stabilizer system consisting of 2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert.butylanilino)-1,3,5-triazine and dilauryl thiopropanoate.

Abstract: Process for the production of polyphenyleneoxide, in which:oxygen, or a gas containing molecular oxygen is fed into a liquid reaction medium, solvent of the 2,6-xylenol and of the catalyst cupric salt complexed with an organic base, but nor solvent or substantially not solvent of the polyphenyleneoxide;from time to time samples are collected of the reaction mixture, said samples are treated with a liquid solvent, capable of dissolving polyphenyleneoxide and of stopping the growth of the macromolecules, until a clear and homogeneous solution is obtained;the through time of the so obtained solution is measured in a capillary tube viscometer and the value is determined of the viscosity and/of the molecular weight of polyphenyleneoxide by the comparison with standard values; andon the basis of the so determined value of the viscosity and/or of the polyphenyleneoxide molecular weight interventions are effected on the oxidative polymerizing reaction of 2,6-xylenol.

Abstract: Preparation of alkylation catalysts containing iron oxide and/or chromium oxide, by means of a process which comprises:(a) precipitating hydrate oxides of iron and/or chromium from an aqueous solution of soluble compounds of said elements;(b) separating the thus obtained precipitate, and washing said precipitate;(c) granulating the washed precipitate, and drying the granules so obtained;(d) calcining said dried granules at high temperature;in which an organic carboxylic acid salt of iron and/or chromium is added to and homogenized with the washed precipitate from stage (b), and/or the dried granules from stage (c) are impregnated with an aqueous solution of an organic carboxylic acid salt of iron and/or chromium.The catalysts obtained by means of the above process are mechanically strong, and highly active in the production process of 2,6-xylenol by means of the alkylation of phenol or o-cresol with methanol.

Abstract: Process for the production of polyphenylene oxide by means of the oxidative polymerization of 2,6-xylenol, with either oxygen or a gas containing molecular oxygen, in the presence of a catalyst, by continuously operating in a circulation system, and with the precipitation of the polymer in the liquid reaction medium.