Green synthesis of xylan hemicellulose esters

BIOVERT+FZB:CPIThe esterification of xylan type hemicelluloses, isolated from birchwood, was carried out firstly in homogeneous conditions using N,N-dimethylformamide (DMF) and lithium chloride (LiCl) in the presence of 4-dimethylaminipyridine (DMAP). The degree of substitution (DS) of xylan acetates ranged between 0.9 and 2.0 as a function of experimental conditions. Due to the problems of toxicity and recycling of DMF, an alternative method of esterification is reported in the second part of this work, performing in the absence of organic solvent and using DMAP or methanesulfonic acid (MSA) as catalysts. Acetylation reaction catalyzed by MSA was developed through an experimental design in order to achieve the highest DS under the mildest conditions. The significant factors and their interactions were identified. The optimization of reaction parameters allowed to obtain a high DS (1.6) and maximal yield (85%). Moreover, the reactivity of propionic and hexanoic anhydrides was evaluated and hydrophobic xylan esters with low degrees of substitution were obtained. (C) 2011 Elsevier Ltd. All rights reserved

Hemicelluloses cationization: comparison of liquid and solid phase preparation processes

SSCI-VIDE+CDFA+CPI:FRAInternational audienceNon

Prevention of photoyellowing of high-yield pulps using ternary mixtures containing a UV screen, a polyethylene oxide dithiol and sucrose

Trials were carried out on printing papers containing different high-yield pulps (SGW) poplar CTMP softwood PGW) to protect them against photoyellowing using mixtures containing the commercial UV absorber Tinuvin 1130 (T1130), a polyethylene oxide dithiol (PEG) and sucrose. Emulsions were prepared with these chemicals and oleic acid by dynamic stirring. Size-press technology was used to deposit each protecting emulsion on the surface of papers. Colour reversion was efficiently reduced by the three-component mixture; nevertheless to limit significantly the brightness reversion the sucrose charge must be sufficiently high. Trials with an experimental paper machine equipped with a size press confirmed the laboratory results and showed that the protecting emulsion does not perturb the paper sheet formation

Hemicelluloses cationization: comparison of liquid and solid phase preparation processes

SSCI-VIDE+CDFA+CPI:FRAInternational audienceNon

Oxalic acid: a microbial metabolite of interest for the pulping industry

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Energy saving with fungal enzymatic treatment of industrial poplar alkaline peroxide pulps

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Genetic selection within Douglas fir (pseudotsuga menziesii) in Europe for papermaking uses

International audienceThe study aims to identify the feasibility and the relevance of a genetic selection for enhancing the pulping potential of the Douglas fir wood. At first, wood predictors for TMP potential are identified through the refining of thirty trees 17-year-old, using a specific procedure on a 12" Andritz refiner. The variations of TMP physical properties are linked with those of anatomical parameters, but also with within ring density related traits. The brightness of the unbleached TMP is negatively correlated with the red chromatic component of wood. Lignin, holocellulose and extractives content on one hand, Kraft fibre morphology on the other hand are considered to evaluate roughly the wood potential for the Kraft process. Then 15 clones out of 200 are non destructively selected within a 24-year-old German test to evaluate the range of the genetic variation of the papermaking potential. Chemical analyses give evidence of large variations of the chemical composition ratio between clones (holocellulose/lignin ratio). The clone discrimination of the fibre length is weak, but significant differences of fibre coarseness are observed as a consequence of the large variability of the latewood density levels. The industrial selection gain for pulping is discussed on the basis of TMP pilot plant tests which show large differences of physical and optical TMP properties between average wood assortments of each clone. This leads to practical recommendations for breeders considering the expectations of both the pulping and the wood industry.Sélection génétique du Douglas (Pseudotsuga menziesii) en Europe pour des usages papetiers. L'étude vise à connaître la faisabilité et la pertinence d'une sélection génétique pour améliorer le potentiel papetier du bois de Douglas. Dans un premier temps sont identifiés des indicateurs de qualité du bois pour la pâte TMP au travers du défibrage de 30 arbres âgés de 17 ans sur un pilote Andritz 12". Les variations de propriétés physiques des pâtes TMP sont liées à celles de paramètres anatomiques, mais aussi à des variations de densité intra-cerne. La blancheur des pâtes écrues est négativement corrélée à la composante chromatique rouge du bois. Les taux de lignine, holocellulose et taux d'extraits d'une part, les caractéristiques morphologiques des fibres d'autre part, sont mesurés pour évaluer sommairement le potentiel du bois dans le procédé Kraft. Dans un second temps, 15 clones sont sélectionnés parmi 200 de façon non destructive au sein d'un test clonal allemand âgé de 24 ans, afin d'évaluer l'ampleur de la variation génétique du potentiel papetier. Les analyses chimiques mettent en évidence de forts contrastes entre clones du point de vue de la composition chimique (rapport holocellulose/lignine). La différenciation des clones est faible pour la longueur des fibres, à la différence de la masse linéique des fibres, conséquence d'une forte variation de la densité du bois d'été entre clones. Dans une perspective industrielle, le gain potentiel lié à la sélection est discuté sur la base de tests menés dans un pilote TMP qui mettent à jour d'importants écarts de propriétés physiques et optiques des pâtes issues de lots moyens de bois par clone. Ceci conduit à des recommandations pratiques pour les sélectionneurs, tenant compte des attentes respectives de l'industrie des pâtes et de l'industrie du bois

Energy saving with fungal enzymatic treatment of industrial poplar alkaline peroxide pulps

International audienc

Modification of hemicellulose content by antisense down-regulation of UDP-glucuronate decarboxylase in tobacco and its consequences for cellulose extractability

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