Mines ParisTech

About: Mines ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Finite element method & Microstructure. The organization has 6564 authors who have published 11676 publications receiving 359898 citations. The organization is also known as: École nationale supérieure des mines de Paris & École des mines de Paris.

Effect of Al2O3 and TiO2 nanoparticles and APP on thermal stability and flame retardance of PMMA

Abstract: Ammonium polyphosphate (APP)-based additives and Al2O3 and TiO2 nanoparticles have been incorporated separately or combined at a 15 wt% global percentage in poly(methyl methacrylate) (PMMA). APP–based additive containing melamine phosphate has led to an intumescent behavior during cone calorimeter tests, whereas thermal stability was particularly improved by the use of the oxide nanoparticles. APP with melamine phosphate and Al2O3 combination allowed significant synergism on flame retardance to be achieved, owing to the catalytic action of alumina well-dispersed nanoparticles, which modified the decomposition pathway of PMMA and the formation of a charred and ceramized structure. Aggregation processes in the case of TiO2 seemed to limit the catalytic action of the surface and did not allow synergism for flame retardance to be observed. Copyright © 2006 John Wiley & Sons, Ltd.

α decay half-lives of new superheavy nuclei within a generalized liquid drop model

Abstract: The \ensuremath{\alpha} decay half-lives of the recently produced isotopes of the 112, 114, 116 and 118 nuclei and decay products have been calculated in the quasi-molecular shape path using the experimental ${Q}_{\ensuremath{\alpha}}$ value and a Generalized Liquid Drop Model including the proximity effects between nucleons in the neck or the gap between the nascent fragments. Reasonable estimates are obtained for the observed \ensuremath{\alpha} decay half-lives. The results are compared with calculations using the Density-Dependent M3Y effective interaction and the Viola-Seaborg-Sobiczewski formulae. Generalized Liquid Drop Model predictions are provided for the \ensuremath{\alpha} decay half-lives of other superheavy nuclei using the Finite Range Droplet Model ${Q}_{\ensuremath{\alpha}}$ and compared with the values derived from the VSS formulae.

Mode transitions in low pressure rare gas cylindrical ICP discharge studied by optical emission spectroscopy

Abstract: We report optical emission spectroscopy (OES) measurements in cylindrical inductively coupled plasma (ICP) discharges, focusing on E-to-H mode transition in rare gases (Ar, Kr, Xe). The discharge configuration is designed primarily as a radical source for treatment in a high vacuum system, but little is known about its characteristics. Two discharge modes are observed in Ar and Kr on increasing the power injected into the discharge (E-mode at low injected power and H-mode at high injected power). In this paper, we use OES measurements and calculations to infer rare gas discharge characteristics and mode transitions for this geometry in rare gases. It is shown that emission line intensity ratios from the OES signal of a level that is strongly coupled to a metastable state with one whose principal production mechanism is by direct excitation can be used to infer information about the electronic parameters of the discharge.

How Carbon Nanotube Crushing can Improve Flame Retardant Behaviour in Polymer Nanocomposites

Abstract: Nanocomposites based on an ethylene-vinyl acetate copolymer (27 wt.-% vinyl acetate) and multiwall carbon nanotubes (MWNTs) have been prepared by melt blending and their thermal degradation and flame retardant properties have been evaluated. Special attention has been paid to the influence of the nanotube nature on the flammability properties and more particularly on the time to ignition (TTI) as measured by cone calorimetry. It has been shown that there is a strong influence of the nature of carbon nanotubes on the fire behaviour of the composites, especially previous MWNTs crushing proved to substantially delay the TTI while maintaining much reduced heat release rate (HRR). Such a remarkable behaviour might be explained by the chemical reactivity of radical species present at the surface/extremities of crushed MWNTs during the combustion process.