Evolution of mechanical properties and final textural properties of resorcinol-formaldehyde xerogels during ambient air drying

in Journal of Non-Crystalline Solids (2008), 354(10-11), 831-838

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 ... [more ▼]

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. [less ▲]

Applications de la microtomographie à rayons X en génie des procédés

Scientific conference (2007, November)

Intérêt de la microtomographie à rayons X pour la formulation de produits agroalimentaires

in SFGP (Ed.) Récents progrès en génie des procédés N° 96 2007 : actes du 11° Congrès de la Société Française de Génie des Procédés 9-10-11 Octobre 2007, Saint-Étienne, France (2007, October)

Observation of wall effects in activated carbon filters by x-ray µCT

in Mc Cann, H.; Johansen, G. A. (Eds.) Proceedings of the 5th World Congress on Industrial Process Tomography, Bergen, Norway, September 6-9, 2007 (2007, September)

Production of cylindrical carbon xerogel monoliths: effect of sample diameter on drying-induced cracks

Conference (2007, September)

Water desorption isotherms of resorcinol-formaldehyde and carbon xerogels

Poster (2007, July 15)

Re-evaporation of adsorbed (toxic) compounds inside an activated carbon filter

in The American Carbon Society (Ed.) Proceedings of Carbon 2007 (2007, July)

Effect of sample size on the mechanical stresses induced during the convective drying of highly shrinking materials

in Proceedings of the joint conference of AFSIA and Drying Working group of EFCE at Casino Municipal Biarritz, France, 24th and 25th May, 2007 (2007, May)

Non-destructive characterization of deer (Cervus Elaphus) antlers by X-ray microtomography coupled with image analysis

in Journal of Microscopy-Oxford (2007), 225(Pt 3), 258-263

X-ray microtomography coupled with image analysis was tested as a non-destructive alternative method for the textural characterization of the trabecular part of deer antlers (Cervus Elaphus). As gas ... [more ▼]

X-ray microtomography coupled with image analysis was tested as a non-destructive alternative method for the textural characterization of the trabecular part of deer antlers (Cervus Elaphus). As gas adsorption and mercury intrusion cannot be applied on this soft and spongy material, its pore texture was, up to now, determined from histological sections that give only two-dimensional information. In this work, X-ray microtomography is used to scan entire or half pieces of antlers and three-dimensional image analysis is performed in order to assess the differences between samples collected at various antler locations. Results clearly show a porosity profile along the sample diameter. The pore size distribution is showed to be dependent on the sample original site. [less ▲]

3D image analysis characterization of dried banana

Conference (2007, February)