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The effect of extraction conditions on polyphenols contents and condensed tannins by microwave-assisted extraction (MAE) was studied for the first time to our knowledge. Moroccan barks of Acacia mollissima was used to extract phenolic compounds. The variables studied are the following: power extraction, time extraction and solvent nature. Five powers extraction were tested: 150 W, 250 W, 300 W, 450 W and 600 W. A significant effect of power extraction on the extractable nature was proved by ANOVA and Student test. The yields were also affected by time extraction. Different solvent (water, ethanol, methanol and ethyl acetate) were tested to evaluate the best extraction solvent according to the extractable nature. Highest polyphenols contents were obtained with methanol. The proportion of this solvent, time extraction and power extraction were optimized using the response surface methodology (RSM). A face-centered composite design (FCCD) was applied to evaluate the effects of these variables on the polyphenols and condensed tannins contents. For each experiment, the extraction yield, the total polyphenolic contents and the condensed tannins contents were quantified using colorimetric essays. The extracts were characterized by their reactivity to formaldehyde and reverse phase high pressure liquid chromatography (RP-HPLC). The highest polyphenols content was obtained at 156 W using 80% of methanol during 5 min. For condensed tannins, the highest content of cyanidin was obtained at 182 W using 20% of methanol during 3.66 min. RSM applied in MAE, permitted to develop green extraction process of polyphenols and tannins extracted, using lower microwave power and methanol proportion with a shortest time extraction and in the same time improve the quantity of extractables obtained from renewable natural resource. (C) 2015 The Authors. Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

International audience; Weight loss due to fungus Coriolus versicolor has been measured on 614 samples according to the NF EN 113 norm. Up to eight samples were cut at breast height (two opposite radii×four radial positions in heartwood) from 82 mature sessile oaks ( Quercus petraea Liebl.) originating from contrasting regions, silvicultural schedules and site qualities in France. The following points are addressed in the paper: (i) contribution to the total variability for weight loss of the effects ldquotreerdquo, ldquoposition in the treerdquo, as well as their interaction; (ii) percentage of wood samples and trees in each of the five classes of natural durability defined by the norm NF EN 350–2; (iii) test of the effects of region, silvicultural schedule and site quality on weight loss and evaluating their contribution to the total variation; and (iv) correlations at tree level between weight loss and several traits related to tree growth and basic wood properties (density, swelling, grain angle, multiseriate wood rays characteristics, extractives content). The results are discussed with a view to aid the forest manager as well as the log/wood user to take advantage of the high level of between-tree variability observed as natural durability against C. versicolor.

International audience; The total phenolic and the condensed tannins content of the bark, the sapwood and the heartwood of Khaya ivorensis (K. ivorensis) from the natural forest of Gabon was investigated by Folin-Ciocalteu, vanillic assay and acid/butanol methods All these methods showed that the bark, the sapwood and the heartwood of K. ivorensis did not display a significant difference (p \textgreater 0.05) regarding their phenolic content and their condensed tannins content as well. The acetone/water extd. tannins from the bark were characterized by Matrix Assisted Laser Desorption/Ionization time of flight (MALDI-TOF) mass spectrometry and by Fourier Transform IR spectroscopy (FTIR). The presence of fisetinidin, gallocatechin, and trihydroxyflavan monomers was obsd. for the first time. Flavonoid oligomers linked to sugars were found within K. ivorensis condensed tannins. An heptamer formed by mixed fisetinidin, trihydroxyflavan, three dihydroxyflavans, and a carbohydrate dimer including mannose was also identified for the first time in the bark of K. ivorensis. That mahogany hardwood species did not exhibit any antifungal activity against the white rot fungus Coriolus versicolor. However, bark powder decreased the radial fungus growth.

International audience; A formaldehyde-free adhesive consisting of a corn flour/NaOH adhesive mixture and a mimosa tannin/hexamine intermediate component was developed and evaluated for application to wood panels such as particleboards. The main ingredients of this adhesive include corn flour, NaOH, mimosa tannin and hexamine. This study investigated the physical properties (rheological and thermal analysis) of corn flour/NaOH and mimosa tannin/hexamine adhesives as well as mechanical properties of particleboards produced with these adhesives. Thermomechanical (TMA) experiments indicate the best performance of the adhesives to be around the relative mass proportions of 50:50 between corn flour/NaOH and mimosa tannin/hexamine. Former NMR measurements on corn starch and mimosa tannin proved that the two components behave as a polymer blend rather than co-reacting. The laboratory results show that particleboards bonded with the adhesive at this optimal ratio show good mechanical properties. Moreover, the formaldehyde emission levels obtained from boards bonded with the optimal adhesive were considerably lower to those obtained from boards made with control urea formaldehyde. © 2013 Springer-Verlag Berlin Heidelberg.

cited By 59; International audience; The aim of this work is to demonstrate the performances of cornstarch-quebracho tannin-based resins designed as adhesive in the plywood production. In this way, the cornstarch and quebracho tannin was introduced in the classic adhesive formulation in order to supply a part of phenol-formaldehyde (PF). The physical properties (rheological characterization, thermogravimetric analysis and solid phase 13C NMR analysis) of the formulated resins were measured. In order to evaluate the mechanical performances of optimal cornstarch-quebracho tannin-based resins, plywood panels were produced and mechanical properties were investigated. These mechanical properties included tensile strength, wood failure and 3-point bending strength. The performance of these panels is comparable to those of plywood panels commercial PF made. The results showed that plywood panels bonded with cornstarch-quebracho tannin-PF resins (15:5:80, w/w/w) exhibited better mechanical properties than plywood panels commercial PF made. The introduction of small proportions of cornstarch and quebracho tannin in PF resins contributes to the improvement of the boiling water performance of these adhesives. The formaldehyde emission levels obtained from panels bonded with cornstarch-quebracho tannin-PF were lower to those obtained from panels bonded with control PF. Solid state CPMAS NMR spectra indicates that no reaction at all between PF resins and cornstarch and quebracho tannin. Even when reaction does evidently not occur, the addition of cornstarch and quebracho tannin improves markedly the water resistance of PF resins. © 2009 Elsevier B.V.

International audience; The development and optimization of a new, environment-friendly adhesive made from abundant and renewable cornstarch and tannin is described in this study. At present, the production of wood composites mainly relies on petrochemical- and formaldehyde-based adhesives such as phenol-formaldehyde (PF) resins and urea-formaldehyde (UF) resins. Formaldehyde-free cornstarch plus tannin adhesives were evaluated for mechanical and physical properties (shear strength, rheological characterisation and thermogravimetric analysis).

International audience; Inorganic UV absorbers which are widely used today were originally designed neither as a UV blocker in coatings applications, nor for wood protection. In recent years however, there has been extensive interest in these compounds, especially with regard to their properties as a UV blocker in coating applications. In this work, we carried out a comparative study to look into some inorganic and organic UV absorbers used in wood coating applications. The aim of this study is to determine the photostabilisation performances of each type of UV absorbers, to seek possible synergies and the influences of different wood species. We have also searched to find eventual correlation between these performances and the influence of UV absorbers on the film properties. Our study has compared the performances of the following UV absorbers: hombitec RM 300, hombitec RM 400 from the Sachtleben Company; transparent yellow and red iron oxides from Sayerlack as inorganic UV absorbers; organic UV absorbers Tinuvin 1130 and Tinuvin 5151 from Ciba Company. The study was carried out on three wood species: Abies grandis, tauari and European oak. The environmental constraints (in particular the limitation of the emission of volatile organic compounds VOCs) directed our choice towards aqueous formulations marketed by the Sayerlack Arch Coatings Company. The results obtained after 800 h of dry ageing showed that the Tinuvins and the hombitecs present better wood photostabilisations. On the other hand in wet ageing, with the hombitec, there are appearances of some cracks and an increase in the roughness of the surface. This phenomenon is absent when the Tinuvins are used. With regard to these results, the thermomechanical analyses relating to the follow-up of the change of the glass transition temperature (Tg) of the various coating systems, show a different behaviour between the two types of absorbers. However, contrary to organic UV absorbers, inorganic ones tend to increase Tg during ageing, and, consequently decrease the flexibility of films. These phenomena can lead to the appearance of cracks found in the case of the wet weathering.

International audience; Matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry was used to examine the oligomer types and their distribution of jubjube (Zyziphus jujuba Mill.) root bark tannin extract. The flavonoid oligomers, up to hexamers, of lower degree of polymerization than that of commercial tannins, are very frequently covalently linked to carbohydrate monomers and dimers. The site of carbohydrate linkage to the flavonoid has been identified by 13C NMR spectroscopy. Fisetinidin, robinetinidin, catechin and gallocatechin flavonoid units are all present in this tannin, all entering to form mixed oligomers based on these four units. This forbids the classification of this extract as just a simple procyanidin, prorobinetinidin, profisetinidin or prodelphinidin.

Chondrus crispus, or Irish moss, is a common edible red seaweed that can be found on rocky shores in the Northern Atlantic. The cell wall contains carrageenan and C. crispus is the original source of this commercially used thickener. Because of the ecological and economic importance of this red alga a relatively important research literature exists and one of the recent achievements in C. crispus research is the sequencing of its genome. In this chapter we review some of the literature with the aim to promote C. crispus as a model organism for florideophyte red seaweeds. We consider subjects like commercial and historical uses, ecology, genetics, population structure, mating systems, physiology, cell wall biology and genomics. © 2014 Elsevier Ltd.

International audience; The aim of this study was to determine the effect of corn flour content of urea formaldehyde (UF) resin on the panel properties of particleboard. Corn flour was added to UF resin to decrease the free formaldehyde content of particleboard panels. Some physical (thickness swelling and rheological characterization), mechanical (modulus of elasticity, modulus of rupture, internal bond strength and withdrawal of screws) properties and formaldehyde emission of particleboards were evaluated. The results showed that the introduction of small proportions of corn flour (7%, by weight) in UF resins contributes to the improvement of mechanical and physical properties of the boards and reduced their formaldehyde emissions. Hazardous petrochemical UF could be partially substituted in industrial applications by addition of corn flour. To our knowledge, this is the first study on this kind of wood adhesives. © 2012 Published by Elsevier Ltd.

International audience; The wood plastic composites studied in this work are composed of high-density polyethylene matrix and Pinus pinaster wood fibers. Despite some interesting intrinsic properties, this wood plastic composite has limited mechanical properties because of the incompatibility between the polar hydrophilic fibers and the non-polar hydrophobic matrix. In this study, the effects of maleic anhydride-modified polyethylene additive, of carbon chains grafted by acetylation and of wood fiber contents on the tensile mechanical properties of the wood plastic composite were studied. Tensile tests were carried out using digital image correlation as an intrusiveness and robust method for strain measurements. Results showed first that the addition of wood fibers made the wood plastic composite stiffer but less flexible. Acetylation improved the interfacial adhesion properties: the Young modulus was increased and a lower strain at failure was reported. The coupling agent also increased the compatibility but mainly in the case where there was no grafted chain. With regard to the carbon chains, the number of grafts improved the elastic properties while their length did not appear to have any influence. Finally, a scanning electron microscope was used to characterize the post-mortem morphology of the fracture surfaces, the results of which supported the observations obtained from the tensile mechanical properties

A composite comprises a thermoplastic elastomer and a plant flour. This composite has an increased thermal stability and can be used in a construction material. The invention also provides a method for producing the composite, said method comprising the steps of introducing a thermoplastic elastomer and a plant flour into an extruder and extruding the resulting mixt.

International audience; An original heat treatment performed under vacuum pressure was investigated. Maritime pine samples were treated at six different temperatures: 140, 160, 180, 200, 230 and 260A degrees C. The physical and mechanical consequences, i.e. bending strength (MOR), modulus of elasticity (MOE), hygroscopic behaviour, equilibrium moisture contents and anti-swelling efficiency (ASE) were studied. A no-choice feeding test according to the NF EN 117 standard was achieved. Temperatures up to 200A degrees C had no significant effect on wood properties. However, at 230 and 260A degrees C, the decrease in MOR was severe, reaching 42.5 and 62.5%, respectively. Whatever the treatment conditions, wood samples were still highly degraded by termites, revealing no increase in their durability.

International audience; The aim of this work was to reduce the viscosity of formaldehyde-free corn starch–mimosa tannin wood adhesives, without adversely affecting the mechanical properties of the product. The reduction of viscosity was achieved using shear refinement. The study focused on the physical phenomena before cross-linking of the wood adhesive. The physical (rheological characterization) and mechanical (bond strength) properties of formaldehyde-free corn starch and mimosa tannin wood adhesives were measured. The results showed that the shear refinement (290 rpm and 5 min, optimal conditions) reduced the viscosity of the corn starch–mimosa tannin wood adhesives (from 100 000 to 458 Pa s) with the advantage of being stable over time. Mechanical tests showed that the shear refinement did not influence the mechanical properties of corn starch–mimosa tannin wood adhesives.

International audience; Crude wood fibers represent a wide class of renewable resources. The surface modification of such materials via covalent grafting of polymer offers new surface properties with non-leaching coating. The grafting of the polymer chains was achieved by surface-initiated controlled radical polymerization through a grafted xanthate chain transfer agent. Macromolecular design via interchange of xanthate (MADIX) technique was chosen to graft poly(vinyl acetate), polystyrene, poly(n-butyl acrylate) and poly(4-vinylbenzyl chloride)-polystyrene amphiphilic cationic copolymers. Water contact angle measurements highlighted the hydrophobization of the wood fiber surface with a nanoscaled polymer monolayer indicating the appropriate coverage of the fiber. X-ray photoelectron spectroscopy showed the successful grafting of the polymer after drastic washing procedure. The quaternization of the grafted polystyrene-co-poly(4-vinyl benzyl chloride) copolymers with tertiary amine allows the introduction of biocide quaternary ammonium functions while preserving the hydrophobic character of the modified wood fiber when introducing a long alkyl chain in the statistical copolymer. Finally, the cationic copolymer was subjected to Coniophora Puteana to evaluate its propensity to limit the fungi expansion. © 2010 Elsevier Ltd. All rights reserved.

cited By 16; International audience; The objective of this work was to demonstrate the utilisation of cornstarch-mimosa tannin-based resins designed for application as an adhesive in particleboard production. Bond qualities of cornstarch-mimosa tannin-urea formaldehyde (UF) resins and commercial UF resin were assessed by using an automatic bonding evaluation system, prior to production of particleboards panels. In order to evaluate the quality of cornstarch-mimosa tannin-UF resins, particleboards were produced and physical and mechanical properties were investigated. These physical properties included rheological, thermogravimetric analysis and solid phase 13C NMR analysis of resins. Internal bond, surface soundness, thickness swelling, porosity, modulus of rupture and modulus of elasticity mechanical properties of particleboards bonded with cornstarch-mimosa tannin-UF resins were also determined. The results showed that it is possible to add cornstarch and mimosa tannin, respectively, up to 10 and 4% to the UF resin without to alter the physical and mechanical properties of the boards. The performance of these panels is comparable to those of boards made using commercial UF resin. Petrochemical UF resins could be partially substituted in industrial applications by addition of cornstarch and mimosa tannin extracts. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.