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Szczurek A.,CNRS Jean Lamour Institute | Amaral-Labat G.,CNRS Jean Lamour Institute | Fierro V.,CNRS Jean Lamour Institute | Pizzi A.,University of Lorraine | And 2 more authors.
Carbon | Year: 2011

Tannin-formaldehyde carbon aerogels were prepared based on organic gels obtained by sol-gel polymerisation of tannin with formaldehyde that have been dried with supercritical acetone and pyrolysed at 900 °C. Tannins drastically reduce the cost of the gels, typically by a factor five, and polymerise in a wide range of pHs, leading to porous carbonaceous materials whose mesopore fraction ranges from 57% to 78%. The surface area and the total porosity can be as high as 715 m2 g-1 and 95%, respectively. Pore volumes and micro-mesopore-size distributions are similar to those of much more expensive carbon aerogels derived from resorcinol- formaldehyde resin. However, more easily adjustable pore textures may be obtained using tannins as precursors. © 2011 Elsevier Ltd. All rights reserved.

Omrani P.,University of Lorraine | Mansouri H.R.,University of Lorraine | Pizzi A.,University of Lorraine | Masson E.,CRITT BOIS
European Journal of Wood and Wood Products | Year: 2010

Grain direction has some influence on linear wood welding, but such differences are smaller with a newer welding technology and furthermore can be overcome by different techniques. © 2009 Springer-Verlag.

A double climatic chamber based on the guarded hot box method was designed to study the hygrothermal behaviour of different compositions of timber walls. Equipment installed allows to reproduce in the climatic chamber hygrothermal conditions close to real climatic conditions and to assess the evolution of temperature and humidity profiles of the tested walls. This paper deals with the hygrothermal behaviour of a timber-framed wall including hygroscopic materials. The results showed that the ability of the experimental device to reproduce desired conditions made it possible to measure wall thermal properties during steady-state (thermal resistance) and transient conditions (decrement factor and time lag). The hygroscopic behaviour of tested materials was also observed during the tests. © AFM, EDP Sciences 2013.

Amaral-Labat G.,CNRS Jean Lamour Institute | Szczurek A.,CNRS Jean Lamour Institute | Fierro V.,CNRS Jean Lamour Institute | Pizzi A.,University of Lorraine | And 2 more authors.
Microporous and Mesoporous Materials | Year: 2012

New carbon aerogels have been prepared from urea-branched phenol-resorcinol-formaldehyde resin. Such material, called "blue glue" and used as cold-set adhesive for wood, has been modified in order to obtain highly porous organic gels. The latter were prepared at different pH (5, 7 and 9), dried with supercritical methanol, and carbonised at two different heating rates (2.5 and 5 °C min -1). FTIR analysis confirmed the expected chemical structure of the gel, and GC-MS analysis of the solvent condensed after supercritical drying suggested a slight chemical degradation of the gels during the drying process. However, low-density (0.15-0.31 g cm -3), monolithic, carbon gels could be successfully derived from these materials, having high BET surface areas (900-1300 m 2 g -1) and high mesopore fractions (60-80%). These ranges of values originate from the conditions tested for preparing the materials. Such carbon aerogels are two times cheaper than their traditional resorcinol-formaldehyde- based counterparts and present similar, if not more developed, porous structures. © 2012 Elsevier Inc. All rights reserved.

Szczurek A.,CNRS Jean Lamour Institute | Amaral-Labat G.,CNRS Jean Lamour Institute | Fierro V.,CNRS Jean Lamour Institute | Pizzi A.,University of Lorraine | And 3 more authors.
Materials Chemistry and Physics | Year: 2011

Organic and carbon aerogels have been prepared from resorcinol-formaldehyde resin diluted with various amounts of water. Water was exchanged by acetone or ethanol, and the gels were subsequently dried with supercritical acetone or with supercritical ethanol. We showed that the nature of the solvent with which water was exchanged only had a minor impact on the porosity of the resultant aerogels. In contrast, the same solvents used as drying fluids in the supercritical state led to significant differences, but only in the case of diluted gels. When the initial dilution was low, similar results were indeed obtained with both solvents. Ethanol was shown to lead to higher shrinkages and higher bulk densities than acetone. A higher chemical degradation of the resin during the drying process was also observed when ethanol was used. © 2011 Elsevier B.V. All rights reserved.

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