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1.
F. Gaboriaud J. P. Vantelon 《Journal of polymer science. Part A, Polymer chemistry》1981,19(1):139-150
A polyurethane based on diphenyl methane diisocyanate (MDI) and propoxylated trimethylol propane was thermally degraded by using the techniques of pyrolysis and thermogravimetric analysis (TGA) in an inert atmosphere. Identification of pyrolysis gaseous products at 600°C showed that the first degradation step consists of a reversal of the polycondensation process, i.e., dissociation into starting polyol and diisocyanate, followed by the polyol degradation and a probable diisocyanate polymerization. Kinetic parameters were determined using dynamic and isothermal TGA curves. It is shown that the degradation can be closely compared with a random chain scission process. 相似文献
2.
J. Monnier S. Réguer D. Vantelon P. Dillmann D. Neff I. Guillot 《Applied Physics A: Materials Science & Processing》2010,99(2):399-406
The study and prediction of very long-term atmospheric corrosion behaviour of ferrous alloys is of great importance in different
fields. First the conservation of metallic artefacts in museum and the corrosion diagnosis on ferrous reinforcement used in
ancient monuments since medieval times needs reliable data to understand the mechanisms. Second, in the frame of the interim
storage of nuclear waste in France, it is necessary to model the long-term corrosion of low alloy steel overcontainer. The
nature of phases and elements constituting the corrosion layers can greatly influence the corrosion mechanisms. On the one
hand, it is crucial to precisely determine the nature of microscopic phases that can be highly reactive. On the other hand,
some elements as P and S could modify this reactivity. To clarify this point and complementary to other studies using Raman
micro spectroscopy technique, X-rays Absorption Spectroscopy (XAS) under synchrotron radiation plays a crucial role. It allows
one to precisely identify the reactive phases in the corrosion layers. Micro-XAS was required in order to refine the spatial
variation, at micrometer scale, of the predominant Fe oxidation state and to characterise the corresponding corrosion products.
Moreover, the role of minor elements on phase’s stability and the chemical form of these elements in the rust layer, especially
phosphorus and sulphur, was investigated. 相似文献
3.
Legros G Fuentes A Ben-Abdallah P Baillargeat J Joulain P Vantelon JP Torero JL 《Optics letters》2005,30(24):3311-3313
A remote scanning retrieval method was developed to investigate the soot layer produced by a laminar diffusion flame established over a flat plate burner in microgravity. Experiments were conducted during parabolic flights. This original application of an inverse problem leads to the three-dimensional recomposition by layers of the absorption field inside the flame. This technique provides a well-defined flame length that substitutes for other subjective definitions associated with emissions. 相似文献
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A. Fuentes G. Legros H. El-Rabii J.-P. Vantelon P. Joulain J. L. Torero 《Experiments in fluids》2007,43(6):939-948
A non-buoyant laminar diffusion flame has been studied using laser-induced incandescence (LII) and light extinction measurements.
The present flame is established within a laminar boundary layer, producing a complex three-dimensional flow field. This produces
a three-dimensional soot concentration field. LII can provide spatially resolved three-dimensional concentration measurements
of the soot field, nevertheless it requires calibration. Calibration needs to be conducted under identical conditions to the
actual measurements, given the complex interaction between the flow field and soot production. This study reports a calibration
procedure that allows the determination of a calibration constant correlating LII signal to soot volume fraction. The potential
sources of error are identified and quantified. 相似文献
7.
L. Bertrand D. Vantelon E. Pantos 《Applied Physics A: Materials Science & Processing》2006,83(2):225-228
The information that can be retrieved from the study of ancient materials and studies on their conservation rely strongly
on the development and application of new techniques of physical analysis. This is particularly important at a time when global
changes affecting our environment and way of life impose new stresses putting heritage preservation at risk. For this purpose,
synchrotron techniques are particularly suited to the non- (or micro-) destructive characterisation of such heterogeneous
materials, and a steep increase in the number of publications has been noticed recently from cultural heritage works using
synchrotron radiation.
In 2004, an interface dedicated to archaeology and cultural heritage was launched at the SOLEIL synchrotron to allow researchers
from the international scientific community to be granted specific expertise. This interface aims at easing the access of
researchers to the synchrotron, facilitating contacts, providing technical support and informing the community. The very first
applications of SOLEIL beamlines in the heritage field are illustrated through works recently carried out at the first beamline
of SOLEIL, LUCIA, currently located at the Swiss Light Source (SLS). The setup of the beamline is succinctly described.
PACS 07.85.Qe; 87.59.-e 相似文献
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Jean-Pierre Vantelon Bnigne Lodeho Stephane Pignoux Janet L. Ellzey Jos L. Torero 《Proceedings of the Combustion Institute》2005,30(2):2239-2246
In this paper, an experimental study on the forward combustion of a bed of tires and refractory briquettes is presented. Temperature measurements within the reactor were obtained as a function of time as well as the evolution of the fuel bed. The products of combustion were cooled down, and usable liquid fuel was recovered and measured. The reaction was found to become unstable for fuel concentrations lower than 50%. The results show that the airflow and tire concentration define different modes of combustion while the reaction remains oxygen limited. Oil production is maximized when an increase in airflow leads to a transition from a rate-limited reaction to a heat transfer-limited propagation. Variation of the tire concentration shows the importance of the inert in achieving high conversion rates. 相似文献
10.
F. Gaboriaud J. P. Vantelon 《Journal of polymer science. Part A, Polymer chemistry》1982,20(8):2063-2071
The various pathways of degradation of polyurethane based on MDI and propoxylated trimethylol propane were studied from the analysis of degradation gases sampled at various temperatures during the heating rise. From the beginning of degradation (250°C) to 400°C, we suggest that the main mechanism is the fracture of the polyurethane molecule into primary amine, carbon dioxide, and propenyl ether, the last leading to propene. Beyond this temperature, the mechanism may be reduced to a depolymerization process followed by radical breakdown of the polyol chain and by stripping and rearrangement of simple radicals, all of these giving the gaseous species obtained. 相似文献