Impregnation du polyterephtalate d'ethylene glycol par des composes terephtaliques-methode statique-methode dynamique

A study was made of the sorption of various terephthalic compounds in samples of ethylene glycol polyterephthalate with various morphologies. A static and a dynamic method of impregnation were employed and compared. The dynamic method can be applied to a study of every system of two phases animated by a uniform relative movement of translation, whereas the static method is more rigorous. Only the amorphous polymer treated with solvent (dioxane) absorbs relatively large quantities of terphthalic compounds at temperatures below the vitreous transition point of the polymer. The absorbed product becomes distributed near the surface of the material, and can be fixed there by thermal treatment subsequent to impregnation. This thermo fixing causes the collapse of the swollen macromolecular structure engendered by the solvent treatment. It is thus possible to modify the surface properties of the polymer.     

Calcul des stabilites relatives d'hydrocarbures derives du bicyclo[2.2.1]heptane. Mise en evidence,de torsions induites par les substituants et d'inte

The ΔG° standard free enthalpy différences between isomeric bicyclo-heptane hydrocarbons derivatives have been calculated via molecular mechanics calculation of the equilibrium geometry of each isomer, calculation of energies using PCILO method, and estimation of entropy values. The calculated ΔG° values are in good agreement with experimental values measured for mono and dimethyl bicyclo[2.2.1]heptane at equilibrium.     

Reduction des interferences sur la determination des metaux lourds dans les sediments de cours d'eau et les boues de stations d'epuration par spectrometrie d'absorption atomique en four graphite

(Reduction of interferences in the determination of trace heavy metals in river sediments and sewage sludges by electrothermal atomic absorption spectrometry.)The interferences of synthetic matrices of river sediments and sewage sludges in the determination of lead, copper, cadmium, chromium and nickel by electrothermal atomic absorption spectrometry were studied; Pb, Cd and Ni were the most sensitive to interferences. The effects of hydrochloric, nitric, perchloric and hydrofluoric acids were tested; perchloric acid was found to interfere most during the determinations. Hydrofluoric acid must be eliminated by evaporation. Techniques for reducing chemical interferences were evaluated. The best method was found to be matrix modification with ammonium dihydrogenphosphate and ascorbic acid for the determination of lead and nickel, and rapid heating (Max Power) for the determination of cadmium. Determinants of copper and chromium were less prone to interference.     

Mise en evidence par rmn 13C et Ir d'enolates mixtes formes par reaction d'echange entre enolates lithiens et sels de metaux divalents

Mixed enolates (RO)₂LiMgBr $\text{4}$ and (RO)₂LiZnBr $\text{5}$ are obtained by addition of MgBr₂ or ZnBr₂ to the lithium enolate of 2,2-diMe pentanone-3

. The mixed magnesium enolate $\text{4}$ is further transformed to ROMgBr with an additional equivalent of MgBr₂ while $\text{5}$ is unchanged by additional ZnBr₂. The same mixed species are observed in the direct addition of preformed enolates.     

Comportement sous impact electronique d'allenes ω-fonctionnels et des acetyleniques isomeres. Mise en evidence du transfert d'un chlore et d'un hydroxyle par un rearrangement de type mclafferty a l'aide de la spectrometrie cid-mike.

This paper describes the use of collision induced dissociation spectra in structural elucidation of C₄H₅X^+. ions, formed by chlorine or hydroxyl group migration in a McLafferty type rearrangement of the molecular ion of (ω-functionnalized allenes and their isomeric acetylenes.     

Caracterisation physico-chimique de couches minces de polymere obtenues par decharge electrique dans des vapeurs de styrene

Thin polymer layers, obtained by polymerization of styrene vapour in an electrical discharge, are insoluble in solvents for usual polystyrene. However, characterization of the gas discharge polymer, by i.r. spectroscopy, by visible and near u.v. spectroscopy and by chemical microanalyses, show that this material is very near to ordinary polystyrene; this conclusion is further indicated by similarity of the glass transition temperatures of the polymers. However, there are some spectral differences, and an evident reactivity to oxygen and to atmospheric moisture.