Cette étude présente une dimension économique, sociale et environnementale très importante. Elle rentre dans le cadre du projet Franco-Marocain PHC Toubkal (Ecopama, Volubilis 2012). Son objectif majeur est de valoriser les écorces Marocaine d’Acacia mollissima par une extraction verte permettant l’obtention des produits réactifs, des tanins condensés, qui seront utilisés dans le collage des panneaux de contreplaqués. Trois méthodes d’extraction ont été étudiées. Deux sont conventionnelles, une macération et une infusion ; ces deux techniques d’extraction sont simples, peu coûteuses. La troisième est une extraction assistée par micro-ondes ; c’est une technique innovante, rapide et peu consommatrice en solvant. La méthodologie des plans d’expériences est utilisée dans cette étude pour déterminer les facteurs les plus significatifs pour l’amélioration du rendement d’extraction des tanins condensés, optimiser les conditions d’extractions, réduire la proportion de solvant utilisé ainsi que le temps d’extraction. L’impact des conditions d’extraction et des méthodes d’extraction sur la teneur des tanins condensés sont étudiés pour la première fois pour les écorces d’Acacia mollissima du Maroc. Les extraits ont été caractérisés par des dosages colorimétriques, par des analyses structurales et thermiques. Les trois méthodes d’extraction ont été comparées. La teneur des extractibles est affectée par la proportion de solvant utilisé et le temps d’extraction. L’extraction assistée par micro-onde présente des teneurs en tanins condensés supérieure à l’extraction par des méthodes conventionnelles mais la teneur en sucre extraits est aussi élevée. Des formulations de colles à base de tanin et de lignosulfonate ont été élaborées en utilisant l’hexamine comme durcisseur. La colle biosourcée et ses constituants ont été caractérisés par analyse thermogravimétrique (ATG), et par calorimétrie différentielle à balayage (DSC). Les propriétés thermomécaniques et mécaniques des colles élaborées sont évaluées. L’optimisation des conditions de pressage des panneaux de contreplaqués, ainsi que le ratio tanin-lignosulfonate glyoxalé, ont été réalisées. La résistance des panneaux à l’eau froide et chaude est améliorée par l’addition de la résine époxy aux formulations de colle. Les propriétés mécaniques des panneaux de contreplaqués encollés ont été évalués par des tests normatifs et ont été comparés à celle des résines synthétiques commerciales (urée formaldéhyde et phénol formaldéhyde). La qualité de collage des panneaux élaborés a été évaluée. Les différentes colles présentent des caractéristiques physiques et thermiques satisfaisantes et acceptables pour les industries de collage des panneaux de bois. Des panneaux de contreplaqués avec de bonnes performances mécaniques et une excellente résistance à l’eau froide et bouillante ont été fabriqués. Ces colles présentent une qualité de collage qui se rapproche de celle des résines phénol-formaldéhyde, et peuvent être utilisées avec succès, pour une application industrielle des panneaux de contreplaqués, en milieu sec, humide et extérieur. / This study has an important economical, social and environmental dimension. It was conducted within the framework Franco-Moroccan PHC Toubkal "Ecopama, Volubilis 2012". The desire to enhance Moroccan bark of Acacia mollissima by the use of green extraction and also to obtain reagent products, condensed tannins, was the main objective of this study. These tannins will be used in the bonding of plywood panels. Three extraction methods were studied. Two are conventional, maceration and infusion; witch is simple and cheap extraction method. The third is microwave assisted extraction which is a fast, innovative method using a small amount of solvent. The experimental design methodology was used to identify the significant factors to improve yield extraction of condensed tannins, to optimize extraction process, to reduce solvent proportion and time extraction. The impact of extraction conditions and extraction process were studied for the first time on condensed tannins contents extracted from Moroccan bark of Acacia mollissima. The extracts were characterized using colorimetric assays, structural and thermal analysis.The three types of extraction were compared. The extractibles contents were affected by solvent proportion and also time extraction. Microwave assisted extraction produced a higher condensed tannins than the conventional method but in the other hand the sugars extracted is more important. Tannin-lignosulfonate adhesives were produced using hexamine as a hardener. The biobased adhesive formulations and their compounds were compared using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and by determining the thermal and mechanical proprieties of the adhesives. Optimal tannin-glyoxalated lignosulfonates ratio and pressing conditions of plywood panels were measured. The resistance of plywood panels to the cold and hot water was improved by the addition of epoxy resin in adhesive formulations. Mechanical properties of plywood panels made with tannin-lignosulfonates-epoxy adhesives were evaluated using normative standard and compared to those of panels made with a commercial resins (urea formaldehyde and phenol formaldehyde). The bonding quality of plywood panels elaborated was evaluated. The various adhesives elaborated have satisfactory and acceptable physical and thermal characteristics for bonding panels used in wood industries. Plywood panels with good mechanical performance, good resistance to cold water and to boiling water, were produced. The bonding quality of the adhesives elaborated in laboratory scale presented approximate proprieties than the phenol-formaldehyde resins which can use with successfully in dry, wet and exterior industrial application of plywood panels.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this research was to evaluate tree pasture-based systems (PS) with elephant grass (EG) + spontaneous growing species (SGS), ryegrass (RG), for PS1; EG + SGS + forage peanut, for PS2; and EG + SGS + RG + red clover, for PS3. EG was planted 4 m spaced rows. In the cool-season, ryegrass was sowed between rows of EG; red clover was sowed and the forage peanut was preserved in respectively PS. Experimental design was completely randomized with tree treatments (SF), two replicates (paddocks) in completely split-plot time (grazing cycles). Holstein cows receiving 5.5 kg-daily and a complementary concentrate feed were used in the evaluation. The herbage mass parameters, botanical composition, forage production and stocking rate were evaluated. Samples were collected by the hand-plucking method to analyze the organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and organic matter in situ digestibility (OMISD) of pasture; phenols and tannins on legumes. Nine grazing cycle were performed during the experimental period (341 days). The mean values of forage production, stocking rate, crude protein and digestibility were 17.14; 16.80; and 19.47 t/ha; 3.28; 3.34; and 3.60 UA/ha; 13.86; 15.39; and 14.78%; 78.33; 79.23; and 79.94% on the respective PS. SGS increased significantly (P≤0,05) relation to the PS without forage legume. Similar results were observed for forage production OM an NDF in comparison to PS. Nutritive value was similar between forage legumes. Differences (P≤0,05) on condensed tannin tenors were observed between forage legumes. Considering the forage production, stocking rate and nutritive value, the PS mixed to forage legumes showed better performance. / O objetivo desta pesquisa foi avaliar três sistemas forrageiros (SF) com capim elefante (CE), espécies de crescimento espontâneo (ECE), azevém anual (AZ), como SF1; CE + ECE + AZ + amendoim forrageiro (AF), como SF2; e CE + ECE + AZ + trevo vermelho (TV), como SF3. O capim elefante foi estabelecido em linhas afastadas a cada 4 m. No período hibernal fez-se o estabelecimento do AZ entre as linhas do capim elefante; o trevo vermelho foi semeado e o amendoim forrageiro foi preservado, considerando os respectivos tratamentos. O delineamento experimental foi o inteiramente casualizado, com três tratamentos (SF), duas repetições (piquetes) em parcelas subdivididas no tempo (pastejos). Para avaliação foram usadas vacas da raça Holandesa que receberam complementação alimentar com concentrado à razão de 5,5 kg/dia. Foram avaliados parâmetros da massa de forragem pré-pastejo, a composição botânica, a produção de forragem e a lotação. Para analisar a matéria orgânica (MO), a fibra em detergente neutro (FDN), proteína bruta (PB) e digestibilidade in situ da MO (DISMO) da pastagem e os teores de fenóis e taninos das leguminosas, foram coletadas amostras de pastejo simulado. Durante o período experimental (341 dias) foram efetuados nove ciclos de pastejo. Os valores médios de produção de forragem, lotação, PB e de DISMO foram 17,14; 16,80; e 19,47 t/ha; 3,28; 3,34; e 3,60 UA/ha; 13,86; 15,39; e 14,78%; 78,33; 79,23; e 79,94% nos respectivos SF. Houve aumento significativo (P≤0,05) para espécies de crescimento espontâneo na pastagem sem leguminosa. Resultados similares foram observados entre SF para MO e FDN. O valor nutritivo foi similar entre as leguminosas forrageiras. Foram observadas diferenças (P≤0,05) entre as leguminosas para os teores de taninos condensados. Considerando a massa de forragem, a lotação e o valor nutritivo, as pastagens consorciadas com leguminosas forrageiras apresentaram melhor desempenho.

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