[en] Resorcinol-formaldehyde gels were produced at 50, 70 and 90 degrees C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied in order to optimize the synthesis conditions. The convective air-drying process was used, and the drying duration was studied with regard to the synthesis conditions. The aging time has no effect on the pore texture after 24 h at 90 degrees C or 48 h at 70 C, whatever the R/C value. The synthesis-aging step can be shortened by increasing the temperature. Nevertheless, the pore size tends then to decrease, especially when R/C is high, but this can be counterbalanced by increasing R/C. Moreover, bubbles often appear in the gel at high synthesis temperature, which limits the temperature to about 70 degrees C in the case of monolithic parts. At 70 degrees C and with an air velocity of 2 m/s, the elimination of 90% of the solvent requires 1 h drying when the pore size reaches 400-600 nm, 2.5 h for 50 nm wide pores and 3 h when the pore size decreases to 15-20 nm. The drying duration does not exceed 8 h in all cases and could be shortened by increasing the temperature at the end of the process. (c) 2005 Elsevier B.V. All rights reserved.
Disciplines :
Materials science & engineering
Author, co-author :
Job, Nathalie ; Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Génie catalytique
Panariello, Fabian
Marien, José ; Université de Liège - ULiège > Chimie générale et chimie physique
Crine, Michel ; Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Opérations physiques unitaires
Pirard, Jean-Paul ; Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Génie catalytique
Léonard, Angélique ; Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Opérations physiques unitaires - Département de chimie appliquée
Language :
English
Title :
Synthesis optimization of organic xerogels produced from convective air-drying of resorcinol-formaldehyde gels
Alternative titles :
[fr] Optimisation de la synthèse de xérogels organiques à partir du séchage convectif de gels résorcinol-formaldéhyde
Publication date :
01 January 2006
Journal title :
Journal of Non-Crystalline Solids
ISSN :
0022-3093
Publisher :
Elsevier Science Bv, Amsterdam, Netherlands
Volume :
352
Issue :
1
Pages :
24-34
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
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