Poitiers, France
Poitiers, France
Time filter
Source Type

Bonnafous C.,CNRS Pprime Institute | Touchard F.,CNRS Pprime Institute | Chocinski-Arnault L.,CNRS Pprime Institute | Dever C.,VALAGRO
Materiaux et Techniques | Year: 2011

In this paper, a multi-scale analysis of the architecture and of the mechanical behaviour of woven hemp fabric/epoxy composites is developed. A comparison with glass and flax fabric composites is performed at each step. The architecture of glass, flax and hemp yarns was first studied and statistical analyses were used to evaluate their mechanical behaviour. In order to characterise the mechanical properties of woven hemp fabric/epoxy composites, a multi-scale analysis is developed, based on a three steps analytical model built from the mechanical properties of the elementary components of the fibre: cellulose fibrils, lignin and hemicellulose. The natural fibres variability is determined from experimental results and integrated in the analytical modelling. Results obtained with the model provide an estimation of the mechanical properties of woven hemp fabric/epoxy composites. © 2011 EDP Sciences.

Guillebaud-Bonnafous C.,University of Poitiers | Guillebaud-Bonnafous C.,Institute Of Mecanique Et Dingenierie Of Bordeaux | Touchard F.,University of Poitiers | Chocinski-Arnault L.,University of Poitiers | Dever C.,Valagro
Annales de Chimie: Science des Materiaux | Year: 2012

In the present work, the link between an impregnated hemp yarn and the epoxy matrix has been investigated. The micromechanical tests usually used to characterize the fibre/matrix interface have been adapted to study the yarn/matrix interface and have been associated with experimental techniques which enable the measurement of stress and displacement fields. Single yarn composite specimens with yarn axis at 0° or 90° from the loading direction have been developed. Fragmentation tests have been performed to determine the critical interfacial shear strength. The changes of stress field during fragmentation process show a stress redistribution which occurs at 45° from the tensile loading direction. Strain fields have been tracked by digital image correlation on the edge of single yarn composite specimens with yarn axis at 90° from the loading direction. Results allowed the determination of the behaviour law of points located in the yarn, in the matrix and at the yarn/matrix interface. © 2012 Lavoisier.

Dubois J.-L.,Arkema | Piccirilli A.,Valagro | Magne J.,Valagro | He X.,U.S. Department of Agriculture
Industrial Crops and Products | Year: 2013

Non-edible oil crops, such as castor or jatropha, contain several toxic components. Post-harvest treatments should be used to reduce the risks associated with the possible dispersion of toxic compounds in the environment. A new processing technology named reactive seed crushing was developed, which combines in a single process seed-crushing, solvent extraction, oil refining, transesterification and meal detoxification. When applied to castor seeds, it was demonstrated that the process produced a detoxified meal and a castor oil methyl ester of acceptable quality for downstream processing. © 2012 .

Beauchet R.,Laboratoire Of Catalyse En Chimie Organique | Pinard L.,Laboratoire Of Catalyse En Chimie Organique | Kpogbemabou D.,Laboratoire Of Synthese Et Of Reactivite Des Substances Naturelles | Laduranty J.,Laboratoire Of Synthese Et Of Reactivite Des Substances Naturelles | And 6 more authors.
Bioresource Technology | Year: 2011

The direct liquefaction of a biomass composed of a mixture of wastes (straw, wood and grass) was studied using Nickel Raney as catalyst and tetralin as a solvent. Tetralin allows to solubilize green waste from 330°C at relatively low hydrogen pressure, and avoids the recondensation of the intermediate products. The green waste deoxygenation results mainly from a decarboxylation reaction. The addition of Raney Ni in the feed, increases the gas yield due to methane formation, without diminishing the yield in solvolysis oil. The catalyst hydrogenolyses the small molecules present in the light fraction. Moreover, it improves the quality of the oil by increasing the hydrogen transfer between the solvent and the solvolysis oil. As a consequence, the oxygen content decreases and the yield of oil soluble in hexane strongly increases. The catalyst allows to obtain straight long chain alkanes (C 13-C 26), which result from the hydrogenation of the extractives compounds of the green waste. © 2011 Elsevier Ltd.

Povero G.,PlantLab | Loreti E.,CNR Institute of Agricultural Biology and Biotechnology | Pucciariello C.,PlantLab | Santaniello A.,PlantLab | And 6 more authors.
Journal of Plant Research | Year: 2011

In nature, plants can recognize potential pathogens, thus activating intricate networks of defense signals and reactions. Inducible defense is often mediated by the detection of microbe or pathogen associated molecular pattern elicitors, such as flagellin and chitin. Chitosan, the deacetylated form of chitin, plays a role in inducing protection against pathogens in many plant species. We evaluated the ability of chitosan to confer resistance to Botrytis cinerea in Arabidopsis leaves. We subsequently treated Arabidopsis seedlings with chitosan and carried out a transcript profiling analysis using both ATH1 GeneChip microarrays and quantitative RT-PCR. The results showed that defense response genes, including camalexin biosynthesis genes, were up-regulated by chitosan, both in wild-type and in the chitin-insensitive cerk1 mutant, indicating that chitosan is perceived through a CERK1-independent pathway. © 2011 The Botanical Society of Japan and Springer.

Loading VALAGRO collaborators
Loading VALAGRO collaborators