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Titolo:
Synthesis and properties of some monolithic silica carbogels produced frompolyethoxydisiloxanes dissolved in ethylacetoacetate (etac) and acid catalysis
Autore:
Begag, R; Pajonk, GM; Elaloui, E; Chevalier, B;
Indirizzi:
Univ Lyon 1, UMR CNRS 5634, LACE, F-69622 Villeurbanne, France Univ Lyon 1 Villeurbanne France F-69622 CE, F-69622 Villeurbanne, France ENI Gabes, LCE, Gabes 6029, Tunisia ENI Gabes Gabes Tunisia 6029ENI Gabes, LCE, Gabes 6029, Tunisia CSTB, F-38400 St Martin Dheres, France CSTB St Martin Dheres France F-38400 B, F-38400 St Martin Dheres, France
Titolo Testata:
MATERIALS CHEMISTRY AND PHYSICS
fascicolo: 3, volume: 58, anno: 1999,
pagine: 256 - 263
SICI:
0254-0584(19990415)58:3<256:SAPOSM>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
AEROGELS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Pajonk, GM Univrance 1, UMR CNRS 5634, LACE, 43 Bd 11-11-1918, F-69622 Villeurbanne, F Univ Lyon 1 43 Bd 11-11-1918 Villeurbanne France F-69622 ne, F
Citazione:
R. Begag et al., "Synthesis and properties of some monolithic silica carbogels produced frompolyethoxydisiloxanes dissolved in ethylacetoacetate (etac) and acid catalysis", MATER CH PH, 58(3), 1999, pp. 256-263

Abstract

The aim of the present work described in this paper was to synthesize transparent and superinsulating monolithic carbogels in order to use them as transparent double window insulation spacers at the laboratory scale. The monolithic silica carbogels were made by sol-gel technique using mixtures of anew family of precursors noted PEDS-Px (or polyethoxydisiloxanes which areprepolymers of silica differing by their substoichiometric hydrolysis degrees) [G.M. Pajonk et al., J. Non-Cryst. Solids 186 (1995) 1] with organic solvents in the presence of hydrofluoric acid with no excess of water added,and subsequent drying in the supercritical conditions with respect to CO2 [P.H. Tewari et al., in: L.L. Hench, D.R. Ulrich (Ed.), Science of Ceramic Chemical processing, Wiley, New York, 1986, p. 123], Our research was focused at finding the best conditions of preparation of the monolithic silica carbogels in terms of optical and thermal insulation properties. A new solvent ethylacetoacetate (etac) was found to be much more soluble in liquid CO2than common alcohols and acetone, and the so obtained carbogels, with etac, present very interesting optical visible transmission and thermal properties respectively. The best samples were prepared from mixtures composed of 60% of a prepolymer prepared with 1.8 moles of water per TEOS mole (noted P-900) and 40% of etac ton a volumetric basis), and presented very good transparency close to the one shown by a flat glass pane together with a very small thermal conductivity (unequalled, to the best of our knowledge, by anyother solid material at the present time). (C) 1999 Elsevier Science S.A. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 31/03/20 alle ore 22:36:48