Experimental study of viscoelastic effectives in a cylinder-plane lubricated contact

This experimental study is related to the flow between a stationary small diameter needle and a moving drum of much larger diameter, seen as a moving plane. Our visualisation experimental set-up adds new results regarding the flow behaviour of a polymer solution. This flow is compared to that of a Newtonian fluid used under the same kinematic conditions. Important differences between Newtonian and polymeric flows concern mainly streamlines, stagnation point positions, and reverse flow. A second experimental set-up enabled us to obtain normal stress profiles along the needle wall and the flow rate through the gap. Reslts related to Newtonian flows are compared to the well-known analytical solutions for a bidimensional laminar flow.     

Equations fonctionnelles et systèmes induits en théorie ergodique

Sans résuméEquipe de Recherche n 1 «Processus stochastiques et applications», associèe au C.N.R.S.     

“In-situ” monitoring activation and reaction on very absorbing catalytic solid by DRIFT spectrometer

The FTIR's well-known advantages are strongly shown by the use of new infrared techniques. Both advantages of FTIR and diffuse reflectance make this coupling particularly important in the development of infrared studies.Sensitivity and rapidity of the FTIR spectrometer, added to the extremely simple preparation of the sample, allowed by diffuse reflectance attachment, give a high performing tool particularly in catalysis in the view of understanding the catalytic reactions mechanisms. We have chosen thein-situ study of two catalytic systems active in selective hydrogénation of dienes: a copper-chromium oxide and Cu/Al₂O₃ .     

Applicationsp d⊹omposantes etp absolument sommantes

Le propos de cet article est d’étudier des liaisons entre applicationsp absolument sommantes et applicationsp décomposantes. On donne ensuite quelques applications.      

Thermal degradation of poly(vinyl chloride). I. Structural effects in the initiation and decomposition chain lengths

Four poly(vinyl chloride) samples containing different structural irregularities were thermally decomposed. The rates of HCl evolution were compared to the rates of radical generation in the samples. Orders of stabilities related to the structural entities for the initiation of decomposition and for the chain lengths of HCl evolution were established.