Article (Scientific journals)
Evolution of mechanical properties and final textural properties of resorcinol-formaldehyde xerogels during ambient air drying
Léonard, Angélique; Blacher, Silvia; Crine, Michel et al.
2008In Journal of Non-Crystalline Solids, 354 (10-11), p. 831-838
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Keywords :
drying; shrinkage; texture; resorcinol-formaldehyde xerogels; stress relaxation; viscoelasticity; mechanical properties
Abstract :
[en] Porous carbon xerogels can be obtained by convective drying of resorcinol (R)-formaldehyde (F) hydrogels, followed by pyrolysis. Drying conditions have to be carefully controlled when crack-free monoliths with well-defined shape and size are required. The knowledge of the mechanical properties of the RF xerogels and their evolution with water content is essential to model their thermo-hygro-mechanical behavior during convective drying and avoid mechanical stresses leading to deformation and cracking of the sample. The shrinkage behavior and the mechanical properties of RF xerogels obtained with R/C ratio ranging from 300 to 1500 were investigated. R/C greatly influences the shrinkage and mechanical properties of the wet gel, on the one hand, and the mechanical and textural properties of the dried gel, on the other hand. The smaller the R/C, the higher the shrinkage, the stiffening, and the viscoelastic character of the xerogels. Water content has an influence on both the stiffness of the gels and the viscoelastic response. Generally, samples lose their mechanical viscous character and become more rigid when they are dried. Finally., mercury porosimetry measurements showed that the gels exhibit a marked lowering of their stiffness upon compression, interpreted as a result of the heterogeneity of the microstructure. (C) 2007 Elsevier B.V. All rights reserved.
Disciplines :
Chemical engineering
Materials science & engineering
Author, co-author :
Léonard, Angélique  ;  Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Opérations physiques unitaires - Département de chimie appliquée
Blacher, Silvia ;  Université de Liège - ULiège > Département de chimie appliquée > Labo de génie chimique
Crine, Michel ;  Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Opérations physiques unitaires
Jomaa, Wahbi;  Université Bordeaux 1 > ENSAM - TREFLE
Language :
English
Title :
Evolution of mechanical properties and final textural properties of resorcinol-formaldehyde xerogels during ambient air drying
Alternative titles :
[fr] Evolution des propriétés mécaniques et texture finale de xérogels de résorcinol-formaldéhyde séchés dans des conditions ambiantes
Publication date :
2008
Journal title :
Journal of Non-Crystalline Solids
ISSN :
0022-3093
Publisher :
Elsevier Science, Amsterdam, Netherlands
Volume :
354
Issue :
10-11
Pages :
831-838
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
Available on ORBi :
since 04 February 2009

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