Reference : Evolution of mechanical properties and final textural properties of resorcinol-formaldeh...
Scientific journals : Article
Engineering, computing & technology : Chemical engineering
Engineering, computing & technology : Materials science & engineering
http://hdl.handle.net/2268/5607
Evolution of mechanical properties and final textural properties of resorcinol-formaldehyde xerogels during ambient air drying
English
[fr] Evolution des propriétés mécaniques et texture finale de xérogels de résorcinol-formaldéhyde séchés dans des conditions ambiantes
Léonard, Angélique mailto [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Opérations physiques unitaires - Département de chimie appliquée >]
Blacher, Silvia mailto [Université de Liège - ULg > Département de chimie appliquée > Labo de génie chimique > >]
Crine, Michel mailto [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Opérations physiques unitaires >]
Jomaa, Wahbi mailto [Université Bordeaux 1 > ENSAM - TREFLE > > >]
2008
Journal of Non-Crystalline Solids
Elsevier Science
354
10-11
831-838
Yes (verified by ORBi)
International
0022-3093
Amsterdam
The Netherlands
[en] drying ; shrinkage ; texture ; resorcinol-formaldehyde xerogels ; stress relaxation ; viscoelasticity ; mechanical properties
[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.
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS
http://hdl.handle.net/2268/5607
10.1016/j.jnoncrysol.2007.08.024

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