Dissertations / Theses on the topic 'Lignocellulosic composite'
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1
Padovani, Justine. "Développement d'une chaine de traitement d’images pour relier la morphologie de fibres lignocellulosiques aux propriétés de composites thermoplastiques à fibres courtes." Thesis, Reims, 2019. http://www.theses.fr/2019REIMS046.
Abstract:
L’objectif global de cette thèse est de relier la morphologie des fibres lignocellulosiques aux propriétés fonctionnelles des composites thermoplastiques. Un premier axe de travail a consisté à identifier l’impact du procédé de transformation des fibres sur leurs propriétés finales, en particulier sur leur morphologie. Le second axe a concerné l’étude des liens entre les propriétés des fibres avec les propriétés mécaniques fonctionnelles des composites.Un traitement hydromécanique appliqué à des fibres de chanvre nous a fourni des lots d’échantillons contrastés en termes de morphologie et propriétés physicochimiques. Nous avons généré de la fibrillation, et la nanoindentation a montré une perte de propriétés mécaniques pariétales. Ces propriétés sont fortement corrélées au taux de cristallinité de la cellulose et aux teneurs en 3 monosaccharides : rhamnose, galactose et mannose. Le développement d’une chaine de traitement et d’analyse d’images a permis de quantifier les caractéristiques de taille, de forme et de complexité structurale des fibres à l’échelle des populations. Les caractéristiques morphologiques ont été suivies dans les composites injectés avec ou sans anhydride maléique. Les caractéristiques des mélanges et des composites ont été explorées. Deux rapports de forme (L/D) des fibres ont été distingués (avec et sans fibrillation) et ont été injectés dans des modèles de micromécanique pour évaluer l’influence des fibrillations sur la prédiction du module de Young des composites. À l’échelle du composite la contribution des fibrilles reste très modérée même si la description morphologique individuelle et de population des fibres est significativement amélioréeThe global objective of this thesis is to link the morphology of linocellulosic fibres to the functional properties of composites. A first area of work consisted in identifying the impact of the fibre transformation process on its final properties, in particular on its morphology. The second axis concerned the study of the links between the properties of fibres and the functional mechanical properties of composites.A hydromechanical treatment applied to hemp fibres provided us with contrasting batches in terms of morphology and physicochemical properties. We generated fibrillation, and nanoindentation showed a loss of parietal mechanical properties. These properties are strongly correlated to the crystallinity rate of cellulose and to the contents of 3 oses: rhamnose, galactose and mannose. The development of an image processing and analysis chain has made it possible to quantify the size, shape and structural complexity of fibres at the population level. Morphological characteristics were monitored in composites injected with or without maleic anhydride. The characteristics of mixtures and composites have been explored. Two fibre aspect ratios (L/D) were distinguished (with and without fibrillation) and injected into micromechanical models to assess the influence of fibrillation on the prediction of the Young's modulus of composites. At the composite level, the contribution of fibrils remains very moderate, although the individual morphological and population description of the fibres has been significantly improved
2
Al-Mohamadawi, Ali Abdullah Hassan. "Contribution à l'étude de l'impact de l'environnement vis-à-vis d'éco-matériaux lignocellulosiques." Electronic Thesis or Diss., Amiens, 2016. http://www.theses.fr/2016AMIE0040.
Abstract:
De par leurs faible coût, légèreté et propriétés thermiques, les co-produits lignocellulosiques ont reçu une attention particulière pour la fabrication de bétons légers. Cependant ces co-produits ne sont pas totalement compatibles avec une matrice cimentaire, d'où un retard de prise, des variations dimensionnelles élevées et des résistances mécaniques faibles des matériaux résultants. Pour pallier ces inconvénients, un procédé d'enrobage d'anas de lin avec différentes substances a été adopté. Les composites élaborés présentent des améliorations significatives de leurs comportement hydrique et résistances mécaniques avec une augmentation modérée de masse volumique apparente et de conductivité thermique. Les phénomènes de transfert d'humidité dans les composites obtenus peuvent influencer de manière significative leur durabilité et performance. En effet la plupart des matériaux utilisés dans le bâtiment sont poreux, contenant de l'eau sous forme vapeur ou liquide. La perméabilité à la vapeur d'eau, les isothermes de sorption et la capacité tampon à la vapeur d’eau ont donc été déterminées. Les résultats obtenus montrent la bonne performance hygrique des éco-composites élaborés. Trois tests de lixiviation ont été proposés pour identifier la spéciation chimique des matériaux et évaluer leurs relargages. Les conditions expérimentales ont été choisies pour simuler différents états des composites dans des environnements externes en service ou fin de vie. Le comportement à la lixiviation des composites élaborés diffère peu selon le traitement subi par les anas et la libération de substances toxiques n'a pas été mise en évidenceDue to their low cost, lightness and thermal properties, lignocellulosic byproducts received a particular attention, in the recent years, for manufacturing lightweight concretes. However, these byproducts are not fully compatible with the cement matrix, leading to setting delay, significant dimensional variations, and low mechanical strengths of the composites elaborated. To avoid such drawbacks, a coating process of flax shives using different substances has been adopted in this study. It leads to a reduction in treated shive water absorption compared to raw shives. The composites obtained exhibit significant improvements in hydrous behavior and mechanical strengths with moderate increase in the apparent bulk density and thermal conductivity. The phenomena of moisture transfer in the produced composites can significantly influence the durability and performance of them. In fact most of the materials used in the building area are porous, containing water as vapor or liquid. Therefore the water vapour permeability, sorption isotherms and moisture buffering capacity have been determined. The results obtained show the good hygric performance of the eco-composites elaborated. Three leaching tests have been proposed in this study to identify the chemical speciation of the materials and to evaluate their releasing into the environment. The experimental conditions of the leaching tests have been chosen to simulate different states of our composites in external environments in service or end of life. The leaching behaviour of the cement-based products elaborated differs little according to flax shive treatment and the leaching of toxic substances has not been identified
3
Iyer, Ananth. "Surface characterization of lignocellulosics for composite manufacture /." Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
4
Sbiai, Adil. "Matériaux composites à matrice époxyde chargée par des fibres de palmier dattier : effet de l’oxydation au tempo sur les fibres." Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0043/document.
Abstract:
A travers cette thèse, nous avons pu valoriser les rejets agricoles du palmier dattier (Phoenix L. dactylifera) (fibres issues des folioles) par leur introduction comme renfort fibreux dans la préparation des biocomposites à matrice polyépoxyde (DGEBA/IPD). Le but de la première partie de la thèse était l’étude de la modification chimique des fibres de palmier par oxydation au 2,2, 6,6–tétraméthylpipéridine-1-oxyle (TEMPO). Le suivi cinétique et la topologie de la réaction, ainsi que la caractérisation des fibres à l’état brut et à l’état oxydé, ont été aussi étudiés. Un modèle cinétique original a été proposé ensuite rendant compte du caractère hétérogène de cette réaction chimique. La deuxième partie était consacrée à l’étude cinétique et rhéocinétique de la polymérisation du système DGEBA/IPD seul et en présence de fibres brutes et oxydées. Parallèlement, l’étude thermique de la polymérisation du réseau final a été également réalisée. La dernière partie avait comme but l’étude des propriétés mécaniques aux petites et grandes déformations de ces composites et mettre en évidence l’effet de l’oxydation des fibres sur ces propriétés. D’autre part, le suivi de mise en forme par RTM (moulage par transfert de résine) a montré un effet positif de l’oxydation sur le déroulement de l’injection. Une meilleure mouillabilité du mat des fibres oxydées par la résine est à l’origine de l’amélioration du procédéTo increase in value the agricultural waste products of the date palm tree -phoenix dactylifera l-, especially the fibers from the leaflets, their use as filler in polyepoxide matrix (dgeba / ipd) was investigated to prepare new bio-based composites. Our goal in the first part is to study the chemical modification of palm fiber by oxidation mediated by 2,2,6,6-tetramethylpiperidine-1-oxyl (tempo). The kinetic and the topology of the reaction, as well as the characterization of fibres in rough and oxidized state, were also studied. An original kinetic model was proposed taking into account the heterogeneous character of this chemical reaction. The second part was devoted to study the kinetics and rheokinetic of the polymerization of dgeba / ipd with and without modified and unmodified fibers. This enabled to show the effect of the introduction of the date palm tree fibers (oxidized and non oxidized) on the composite formation. The thermal properties of the prepared composites were also investigated in this part of work. In the last part of this work, the mechanical properties of these composites were investigated and enabled to highlight the effect of the fibers oxidation on these properties. In addition, the effect of oxidation on the course of the injection during the rtm process (moulding by transfer of resin) was investigated. A positive effect of the oxidation of the fibers on the course of the injection was obtained and was attributed to the higher wettability of oxidized fibres by the resin
5
Khemakhem, Marwa. "Valorisation du grignon d’olives : Utilisation comme charge dans des mélanges à matrice polymère." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI002.
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Cette étude est une contribution à la valorisation du grignon d’olives (GO), sous produits oléicoles à caractère lignocellulosique. La voie proposée consiste à utiliser le GO comme charge dans des polymères de grande diffusion à savoir le poly (éthylène/propylène) [CEP] d’origine fossile et le poly (acide lactique) [PLA], issu des ressources renouvelables. Les différentes formulations, CEP/GO et PLA/GO, élaborées à l’état fondu dans une extrudeuse bivis ont été étudiés du point de vue des propriétés rhéologiques, thermique, mécanique et de la morphologie. Différents tiers-corps copolymères de structures diverses ont été utilisés dans le but de promouvoir l’adhésion à l’interface des composants et/ou de réduire la dégradation du polymère matrice et améliorer les performances des systèmes composites ainsi conçus. Les observations morphologiques ont corroboré parfaitement l’ensemble des propriétés étudiéesThis study is a contribution to the valorization of Olive Solid Waste (OSW) which displays a Lignocellulosic nature. The proposed approach consists in using the OSW as a filler in commodity polymers namely the poly (ethylene/propylene) [CEP] of fossil origin and the poly (lactic acid), derived from renewable resources. The different formulations, CEP/GO and PLA/GO, processed in the molten state in a twin screw extruder were studied from the side of rheological, thermal, mechanical properties and morphology. Different copolymers of various structures were used in order to promote the adhesion in the interface of the components and/or to reduce the polymer matrix degradation and to improve the composite systems performances. Morphological observations corroborated perfectly the studied properties
6
Salazar, Vera Lúcia Pimentel [UNESP]. "Estudo da biodegradação das fibras de coco e de sisal visando às aplicações na indústria automotiva." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/101876.
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salazar_vlp_dr_botfca.pdf: 188370 bytes, checksum: aa41f8872ad9416ef8670387131fccce (MD5)Neste trabalho são discutidos os resultados referentes aos ensaios de biodegradabilidade de fibras naturais utilizadas pela indústria auotomobilística: fibra de coco, de coco com látex e e sisal. Estes ensaios foram realizados junto ao Laboratório de Microbiologia Industrial do Agrupamento de Biotecnologia da Divisão Química do Instituto de Pesquisas Tecnológicas do Estado de São Paulo. Apresenta-se uma revisão de literatura sobre biodegradabilidade e sobre as fibras em estudo. Realizou-se a análise elementar de CHN, a qual é um pré-requisito para o Teste da Biodegradabilidade Imediata pela Medida do Dióxido de Carbono Desprendido em Sistema Aberto (norma IBAMA - E.1.1.2. - 1998). Utilizou-se também a norma DIN 53739 (1984) - Testing of Plastics - Influence of dungi and bacteria - visual evaluation - change in mass or physical properties, baseada na ISO 846 - 1978. Fez-se a determinação de extrativos totais, de lignina, de holocelulose e do teor de cinzas das fibras em estudo para se conhecer o teor ral de lignina, celulose e hemicelulose presentes e, compreender os resultados obtidos nos testes de biodegradação. A partir do teste de biodegradabilidade (IBAMA E.1.1.2.-1998), observou-se uma taxa de biodegradação de cerca de 10% para todos os materiais em estudo após 45 dias de ensaio, demonstrando difícil degradação. Nenhum material inibiu a degradação da glicose. No entanto, a porcentagem de degradação da fibra de sisal foi superior a da fibra de coco com látex, conseiderando-se o mesmo intervalo de tempo de cultivo. Quanto a esse teste, pode-se concluir que 45 dias de ensaio é pouco tempo para a biodegradação dessas fibras naturais levando-se em consideração os teores de lignina, celulose e hemicelulose encontrados por Young (1997) para a fibra de sisal e por Han e Rowell (1997) para a fibra de coco. E, analisando-se os teores de lignina, celulose...
Presented in this study are the testing results regarding the biodegradation of natural fibres utilized by automotive industry, in this case, coir and sisal fibers, where the coir fiber was used also as rubberized mat. These biodegradation testing where carried on at th Laboratory of Industrial Microbiology by the Biotechnology Group of the Chemistry Division of the Institute of Technological Research of São paulo State - IPT. Next is presented a literatura review on biodegradation and over the studied fibers, coir and sisal, besides all the details about the testing used evaluate biodegradation and its respectively obtained results. An elementary analysis of CHN was carried out, which is a prerequisite for the Immediate Biodegradation Test of the Mesaure of the Carbon Dioxide Released in Open System (standard IBAMA - E.1.1.2. - 1998). Alson used was the standard DIN 53739 - 1984 - Testing of Plastics - influence of fungi and bacteria - visual evaluation - change in mass or physical properties, established in the ISO 846 - 1978. Also was realized the determination of total extractives, lignin, holocellulose and ash contents of the studied fibers as well as the determination of it's true content and understand the obtained biodegradation testing results. There was hence observed from the biodegradation test (standard E.1.1.2.-1998) a biodegradation tax about 10% for all the studied material after 45 days of assay, which indicates a difficult degradation. None of the material inhibited the glucose degradation. However, the percentage of sisal degradation was greater than that of the coir fiber with latex. It can be concluded about this test, that a 456 day trial is a short lapse of time for the biodegradation of these natural fibers when the contents of lignin, cellulose and hemicellulose that were found by Young (1997) for the sisal fiber and by Han and Rowell... (Complete abstract click electronic access below)
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Molaba, Tshepiso Princess. "Long term effects of temperature and humidity on lignocellulosic fibres and composites." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/10276.
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The study deals with the chemical and flame retardant (FR) treatment of woven flax fabric and preparation and characterization of flax reinforced phenolic composites. Sheets of flax fabric were subjected to chemical treatments using NaOH and silane coupling agents. A phosphate-based flame retardant (DAP) was applied to decrease the flammability of the flax fabric. The effect of the chemical treatments and FR treatments on the thermal and flammability properties of the fabric and composites was investigated using thermogravimetric analysis (TGA), vertical flame resistance test and cone calorimeter. The mechanical properties of the flax fabric and composites, before and after environmental ageing, were investigated. Ageing studies were carried out by exposing the samples in an environmental chamber at specified conditions for two weeks. TGA results showed that the treatment of the fabric with FR shifts the decomposition temperature to lower level and increases the char residue. Vertical flame resistance testing showed that FR treatment of the flax fabric improved the flammability properties. There was no after flame and afterglow observed for FR treated flax fabric due to self-extinguishment after removal of the flame. Flax Fabric without FR burned completely and there was no result for the char length due to the complete destruction of the fabric. The FR treatment, however, seemed to have had a negative effect on the tensile strength of the flax fabric. This was further intensified upon exposure of FR treated flax fabric to high temperatures during ageing studies which drastically reduced the tensile strength by more than 90%, and the flax fabric were found to be brittle and darker in visual appearance. TGA results of flax/phenolic composites showed that for composites containing chemically treated and FR treated flax fabric the decomposition temperatures shifted to lower temperatures; however there was no significant difference in the amount of char residue. Untreated flax/phenolic composites exhibited the lowest char residue. Cone calorimeter results showed that the peak heat release rate (PHRR), smoke production rate (SPR) and carbon dioxide (CO2) emission rate was reduced for the flax/phenolic composite produced using FR treated flax fabric. The tensile strength of these composites was reduced while there was an increase in modulus value. Exposure of the FR treated composites to high temperatures further reduced the tensile strength and increased the E-modulus. Both FR treated and untreated composites changed in colour and the FR treated composites were found to be brittle after exposure to high temperatures.
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David, Grégoire. "Eco-conversion de résidus lignocellulosiques de l'agriculture en matériaux composites durables à matrice biopolyester." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG030.
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Cette thèse consiste à développer et étudier de nouveaux matériaux composites biosourcés et biodégradables à partir de constituants dérivés des déchets de l'agriculture dans le cadre du projet européen NoAW (https://noaw2020.eu). Tous les composants sont dérivés de sous-produits agricoles : des polyhydroxyalcanoates (PHA, biopolyester bactérien et biodégradable en conditions naturelles) produits par digestion anaérobie d’effluents agricoles sont utilisés comme matrices et des fibres de sarments de vigne comme charges de renfort. Les composites sont préparés par extrusion. L'objectif de cette thèse est d'apporter de nouvelles connaissances sur les relations entre le procédé de mise en œuvre des biocomposites, leur structure et leurs propriétés fonctionnelles. Les biocomposites sont développés en considérant une balance performance-coût environnemental. Pour cela, la thèse se focalise sur 2 questions scientifiques majeures : (i) étude de l’impact de l’interface charge/matrice sur les propriétés fonctionnelles des matériaux biocomposites via pré-traitements de surface des particules lignocellulosiques ; (ii) étude de la durabilité de tels matériaux par évaluation dès la conception des impacts environnementaux. Ainsi, une attention particulière est accordée à l’interface charge/matrice, identifiée comme un facteur clé influençant les propriétés finales du composite. Un prétraitement de surface des fibres sans solvant (chromatogénie) est adapté afin de moduler l’interface charge/matrice. Cette nouvelle méthode d’estérification en voie gazeuse est tout d’abord étudiée sur des particules micrométriques de cellulose. Une fois la preuve de concept établie, elle est appliquée aux fibres lignocellulosiques, plus complexes. Les sarments de vigne, déchets agricole abondant en région Occitanie, sont étudiés comme ressource potentielle pour la production de charges de renfort. Une fois collectés et séchés, ils sont broyés en voie sèche afin d’obtenir des particules micrométriques. La variabilité de la matière première étant un des verrous concernant l’utilisation de la biomasse par les industriels, différents cépages sur plusieurs années ont été étudiés. Dans une logique de bioraffinerie, l’extraction préalable de molécules d’intérêt tels que les polyphénols est envisagée avant d’utiliser le résidu, à savoir les sarments épuisés, comme charge de renfort. L’impact environnemental des matériaux développés est évalué afin de guider les choix stratégiques et obtenir le matériau alliant à la fois performance et faible empreinte écologique. Une analyse de cycle de vie dans le cadre d’une application de barquette rigide alimentaire est réalisée en réunissant des données des acteurs de la filière. De plus, une étude de la biodégradabilité des matériaux finaux est menée. Cette thèse englobe plusieurs composantes pluridisciplinaires afin d’avoir une vision d’ensemble et décloisonnée des matériaux composites mis au pointThis thesis aims at developing new fully biosourced and biodegradable composite materials from agricultural residues in the frame of the European project NoAW (https://noaw2020.eu). All the components are derived from agro-wastes: polyhydroxyalkanoates (PHA, bacterial biopolyester and biodegradable in natural conditions) produced by anaerobic digestion of agricultural effluents are used as matrix and vine shoot fibers as fillers. Biocomposites are prepared by melt extrusion. The objective of this thesis is to bring new knowledge on the relationships between the processes used to produce the fillers and the biocomposites, the resulting structure of biocomposites and their functional properties. Biocomposites are developed considering a balance between performance and environmental cost. For this purpose, the thesis focuses on 2 major scientific questions: (i) study of the impact of the filler/matrix interface on the functional properties of biocomposite materials via surface pre-treatments of lignocellulosic particles; (ii) study of the durability of such materials by assessment from the design of the environmental impacts. Thus, special attention is given to the filler/matrix interface, identified as a key factor for the final properties of the composite. A solvent-free surface pretreatment of fibers (chromatogeny) is adapted to modulate the filler/matrix interface. This new method of gas-phase esterification is first studied on micrometric particles of cellulose. Once the proof of concept is established, it is applied to lignocellulosic fibers that are more complex. The vine shoots, agricultural waste abundant in Occitania region, are studied as a potential resource for the production of fillers for composites. Once collected and dried, they are milled using dry fractionation to obtain micrometric sized particles. The variability of the raw material being one of the bottlenecks concerning the use of lignocellusoic biomass by manufacturers, different grape species over several years are studied. In a biorefinery approach, the extraction of molecules of interest, e.g. polyphenols, is considered before using the residue, namely exhausted shoots, as a reinforcing fillers. The environmental impact of the produced biocomposites is evaluated to guide strategic choices and obtain materials displaying a good balance between performance and environmental footprint. A life cycle assessment in the context of a food rigid tray application is carried out, collecting data from sector’s players. In addition, a study of the biodegradability of the final materials is conducted. This thesis encompasses multidisciplinary fields in order to have a decompartmentalized overview of the developed composite materials
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Mousa, A., G. Heinrich, and U. Wagenknecht. "Thermal properties of carboxylated nitrile rubber/nylon-12 composites-filled lignocellulose materials." Sage, 2014. https://tud.qucosa.de/id/qucosa%3A35546.
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Organic hybrid composites based on carboxylated nitrile rubber and nylon-12 reinforced with mercerized and diisocyanated lignocellulose residue (LCR) was prepared. The influence of the LCR on the viscoelastic properties of these organic hybrids was investigated by dynamic mechanical analysis and thermal analysis (differential scanning calorimetry (DSC)). It is found that either the position of the damping peak was shifted to higher values or the intensity of the damping peak was significantly increased with LCR. These results could imply that the LCR enhanced the damping properties of the composites. The thermal stability of the composites was evaluated with the mean values obtained using thermogravimetrical analysis. The decomposition rate was investigated using differential thermal gravimetry. The crystallization behavior of the prepared composites was checked by DSC.
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Carmichael, Eugene. "Biorefining of nanocellulose from waste lignocelluloses using novel ionic liquid processes : feasibility of application in composites." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.695266.
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With the inevitable exhaustion of supplies of oil and other fossil fuels looming on the horizon, coupled with the increasing concern regarding the environmental impact of using these resources, governments worldwide are under pressure to invest in the development of renewable replacements for fuel, as well as natural alternatives to oil based materials such as plastics. One of the main sources of interest is lignocelluloses, comprised of three main components - lignin, cellulose and hemicellulose each of which can be a valuable raw material for fuel or polymer production. The problem however is that the three components are bound together chemically, and efficient separation requires a combination of physical and chemical treatments. It is the aim of this project, therefore, to develop novel processing for the hydrolysis of lignocellulose. The process will involve the use of Ionic Liquids, essentially salts which are liquid below 100°C. While these chemicals have been known of for decades, it is only in the last twenty years or so that research into their potential as solvents, catalysts, reaction media, etc. has accelerated and interest has increased in their use in biorefining. This project is concerned specifically with novel methods incorporating an acidic, hydrophobic ionic liquid in the hydrolysis of lignocellulose with the aim being to produce nanocellulosic fibres and examine their performance as composite fillers. This began with the analysis of novel ionic liquids based on phosphonium and choline cations in the hydrolysis of wheat straw. From this the most promising medium was evaluated in its ability to refine cellulose and compared with a traditional hydrolysis method using dilute sulphuric acid. Furthermore novel lignocellulosic feedstocks, anaerobic digestate and spent mushroom compost, were analysed to determine their suitability as sources for nanocellulosic fibres which would represent an innovative use of these waste materials.
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Ramos, Rógerson Rodrigues Freire. "Desenvolvimento de compósitos de polipropileno (PP) com sabugo de milho (SM) proveniente de resíduos agrícolas." Universidade Federal da Paraíba, 2013. http://tede.biblioteca.ufpb.br:8080/handle/tede/443.
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Previous issue date: 2013-09-09Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Polymer composites reinforced with agricultural lignocellulosic wastes have been widely studied over the years and increasingly realize the value of its use as an alternative to partial substitution of polymeric materials. Furthermore, the use of lignocellulosic materials in composite adds value to this type of waste which has been used mostly in the feeding of animals and/or fertilization of soils. In this work, corn cob (SM) was used as an alternative particulate filler to polypropylene (PP). PP/SM composites were extruded, injection molded and characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile, flexural and impact tests, and morphological analysis was performed by scanning electron microscopy (SEM). Composites with 5, 10, 20 and 30 wt.% corncob were prepared in order to evaluate the effect of filler content on composite properties. TGA analyses showed that thermal stability of the composites is not significantly affected by addition of corncob. DSC analyses showed that PP crystallinity increased with the presence of corn cob particles, however its transition temperatures did not change significantly. SEM photomicrographs of the composites indicated poor filler/matrix adhesion without evidence of effective stress transfer between the phases. Mechanical tests showed satisfactory results with a slight reduction in mechanical strength of the composites with up to 20 % corncob and decreases for higher filler content. This shows that corncob (a renewable, biodegradable and inexpensive material) can be used to partly replace PP (a non-biodegradable thermoplastic polymer derived from nonrenewable fossil source).
Compósitos poliméricos reforçados com resíduos lignocelulósicos oriundos da agroindústria vêm sendo amplamente estudados ao longo dos anos e cada vez mais se percebe o valor de sua utilização como alternativa para substituição parcial de materiais poliméricos. Além disso, o uso de materiais lignocelulósicos em compósitos agrega valor a esse tipo de resíduo tão abundante em todo o mundo e que geralmente é subutilizado na alimentação de animais e/ou fertilização de terras. Este trabalho apresenta o sabugo de milho (SM) como alternativa para carga particulada de enchimento em compósito com matriz de polipropileno (PP). Os compósitos PP/SM foram misturados em extrusora, moldados por injeção e caracterizados por termogravimetria (TG), calorimetria exploratória diferencial (DSC), ensaios mecânicos de tração, flexão e impacto e análise morfológica por microscopia eletrônica de varredura (MEV). Foram utilizados 5, 10, 20 e 30 % em peso de sabugo de milho para avaliar a influência do teor de carga nas propriedades dos compósitos. As caracterizações por termogravimetria demonstraram que a estabilidade térmica dos compósitos não é afetada significativamente com a incorporação do sabugo de milho e as análises de DSC demonstraram que há um aumento da cristalinidade do PP com a presença das partículas de sabugo de milho, porém as faixas de temperatura de transição de fase não sofreram alterações significativas. As fotomicrografias dos compósitos obtidas por MEV indicaram baixa adesão mecânica carga/matriz, com poucos indícios de transferência efetiva de tensões entre as fases, porém, os ensaios mecânicos apresentaram resultados satisfatórios com uma discreta redução na resistência mecânica dos compósitos com até 20 % de teor de carga, prosseguindo com maiores perdas para os compósitos com 30 % de teor de carga de sabugo de milho, indicando que todas as composições são aptas a artigos com aplicações de baixas solicitações mecânicas substituindo parcialmente o polipropileno, um polímero termoplástico com elevado tempo de degradação e oriundo de fonte fóssil não renovável, pelo sabugo de milho, disponível em todo o mundo em abundância, extraído de fonte renovável, é biodegradável e barato, por se tratar de um resíduo.
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Ndata, Kanyisa. "Biochemical characterization of β-xylosidase and β-glucosidase isolated from a thermophilic horse manure metagenomic library." University of the Western Cape, 2020. http://hdl.handle.net/11394/8077.
Abstract:
>Magister Scientiae - MScThe complete degradation of recalcitrant lignocellulose biomass into value-added products requires the efficient and synergistic action of lignocellulose degrading enzymes. This has resulted in a need for the discovery of new hydrolytic enzymes which are more effective than commonly used ones. β-xylosidases and β-glucosidases are key glycoside hydrolases (GHs) that catalyse the final hydrolytic steps of xylan and cellulose degradation, essential for the complete degradation of lignocellulose. Functional-based metagenomics has been employed successfully for the identification and discovery of novel GH genes from a metagenome library. Therefore, this approach was used in this study to increase the chances of discovering novel glycoside hydrolase genes from a horse manure metagenomic DNA library constructed in a previous study. Three fosmid clones P55E4, P81G1, and P89A4 exhibiting β-xylosidase activity were found to encode putative glycosyl hydrolases designated XylP55, XylP81, and BglP89. Amino acid sequence analysis revealed that XylP55, XylP81, and BglP89 are members of the GH43, GH39, and GH3 glycoside hydrolase families, respectively. Phylogenetic analysis of XylP81 and BglP89 indicated that these showed relatively low sequence similarities to other homologues in the respective GH families. The enzymes were expressed and purified, and only XylP81 and BglP89 were biochemically characterized. XylP81 (~58 kDa) and BglP89 (~84 kDa) both showed optimum activity at pH 6 and 50℃ and retained 100% residual activity at 55℃ after 1-hour indicating that they are moderately thermostable. XylP81 had high specific activity against 4-nitrophenyl-β-D-xylopyranoside (pNPX; 122 U/mg) with a KM value of 5.3 mM, kcat/KM of 20.3 s-1mM-1, and it showed enzyme activity against α-L-arabinofuranosidase, β-galactosidase, and β-glucosidase activity. BglP89 had a high specific activity for 4-nitrophenyl-β-D-glucopyranoside (pNPG; 133.5 U/mg) with a KM value of 8.4 mM, kcat/KM of 22 s-1mM-1 and also showed α-L-arabinofuranosidase, β-galactosidase, β-glucosidase, and low β-xylosidase activity. BglP89 also showed low hydrolytic activity on cellobiose, β-glucan, and lichenan indicating that it is a broad specificity β-glucosidase. XylP81 retained ~40% activity in the presence of 3 M xylose whilst BglP89 showed considerable glucose tolerance at 150 mM glucose and retained ~46% residual activity. This study reveals two metagenomic derived enzymes (β-xylosidase and β-glucosidase) showing characteristics that could make them potential candidates for lignocellulose biomass degradation in biotechnological and industrial applications.
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Salazar, Vera Lúcia Pimentel 1972. "Estudo da biodegradação das fibras de coco e de sisal visando às aplicações na indústria automotiva /." Botucatu, 2005. http://hdl.handle.net/11449/101876.
Abstract:
Orientador: Alcides Lopes LeãoBanca: Claudio Angeli Sansígolo
Banca: José Claudio Caraschi
Banca: Derval dos Santos Rosa
Banca: Elisabete Frollini
Resumo: Neste trabalho são discutidos os resultados referentes aos ensaios de biodegradabilidade de fibras naturais utilizadas pela indústria auotomobilística: fibra de coco, de coco com látex e e sisal. Estes ensaios foram realizados junto ao Laboratório de Microbiologia Industrial do Agrupamento de Biotecnologia da Divisão Química do Instituto de Pesquisas Tecnológicas do Estado de São Paulo. Apresenta-se uma revisão de literatura sobre biodegradabilidade e sobre as fibras em estudo. Realizou-se a análise elementar de CHN, a qual é um pré-requisito para o Teste da Biodegradabilidade Imediata pela Medida do Dióxido de Carbono Desprendido em Sistema Aberto (norma IBAMA - E.1.1.2. - 1998). Utilizou-se também a norma DIN 53739 (1984) - Testing of Plastics - Influence of dungi and bacteria - visual evaluation - change in mass or physical properties, baseada na ISO 846 - 1978. Fez-se a determinação de extrativos totais, de lignina, de holocelulose e do teor de cinzas das fibras em estudo para se conhecer o teor ral de lignina, celulose e hemicelulose presentes e, compreender os resultados obtidos nos testes de biodegradação. A partir do teste de biodegradabilidade (IBAMA E.1.1.2.-1998), observou-se uma taxa de biodegradação de cerca de 10% para todos os materiais em estudo após 45 dias de ensaio, demonstrando difícil degradação. Nenhum material inibiu a degradação da glicose. No entanto, a porcentagem de degradação da fibra de sisal foi superior a da fibra de coco com látex, conseiderando-se o mesmo intervalo de tempo de cultivo. Quanto a esse teste, pode-se concluir que 45 dias de ensaio é pouco tempo para a biodegradação dessas fibras naturais levando-se em consideração os teores de lignina, celulose e hemicelulose encontrados por Young (1997) para a fibra de sisal e por Han e Rowell (1997) para a fibra de coco. E, analisando-se os teores de lignina, celulose... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Presented in this study are the testing results regarding the biodegradation of natural fibres utilized by automotive industry, in this case, coir and sisal fibers, where the coir fiber was used also as rubberized mat. These biodegradation testing where carried on at th Laboratory of Industrial Microbiology by the Biotechnology Group of the Chemistry Division of the Institute of Technological Research of São paulo State - IPT. Next is presented a literatura review on biodegradation and over the studied fibers, coir and sisal, besides all the details about the testing used evaluate biodegradation and its respectively obtained results. An elementary analysis of CHN was carried out, which is a prerequisite for the Immediate Biodegradation Test of the Mesaure of the Carbon Dioxide Released in Open System (standard IBAMA - E.1.1.2. - 1998). Alson used was the standard DIN 53739 - 1984 - Testing of Plastics - influence of fungi and bacteria - visual evaluation - change in mass or physical properties, established in the ISO 846 - 1978. Also was realized the determination of total extractives, lignin, holocellulose and ash contents of the studied fibers as well as the determination of it's true content and understand the obtained biodegradation testing results. There was hence observed from the biodegradation test (standard E.1.1.2.-1998) a biodegradation tax about 10% for all the studied material after 45 days of assay, which indicates a difficult degradation. None of the material inhibited the glucose degradation. However, the percentage of sisal degradation was greater than that of the coir fiber with latex. It can be concluded about this test, that a 456 day trial is a short lapse of time for the biodegradation of these natural fibers when the contents of lignin, cellulose and hemicellulose that were found by Young (1997) for the sisal fiber and by Han and Rowell... (Complete abstract click electronic access below)
Doutor
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Hanana, Fatima Ezzahra. "Effet des modifications de surface de fibres lignocellulosiques sur les propriétés morphologiques, mécaniques et physiques de composites à base de polyéthylène linéaire de basse densité par rotomoulage." Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/29820.
Abstract:
Cette thèse se décline en six parties. Le premier volet porte sur la compréhension du procédé de rotomoulage et une description des matériaux composites à base de fibres lignocellulosiques. Le second volet comporte une revue de la littérature sur les composites produits par rotomoulage, tandis que le troisième volet se consacre à la compréhension de la modification des fibres d’érables par le polyéthylène maléisé (MAPE) en solution et son influence et de la teneur en fibre sur les propriétés morphologiques et mécaniques des composites. Le quatrième volet étudie les effets de la taille des particules et la modification en solution, ainsi que la teneur en fibre sur les propriétés morphologiques, thermiques, physiques et mécaniques des composites. Le cinquième volet se penche sur l’effet de la modification, la teneur et la taille des fibres d’érable sur la morphologie et les propriétés physiques et mécaniques des auto-hybrides. Finalement, le dernier volet étudie l’influence de la modification en solution avec du MAPE, la teneur et la taille des fibres sur la morphologie et les propriétés mécaniques des composites hybrides à base de fibres d’érable et de chanvre. Les résultats montrent que les fibres (érable et chanvre) ont été modifiées avec succès par le MAPE en solution, ce qui a amélioré la qualité de l’interface fibre-matrice des composites, conduisant à de meilleures propriétés mécaniques. En outre, les résultats ont prouvé que l’effet de la taille de particule était significatif. En effet, le module de traction augmente jusqu’à 73% lors de l’utilisation de fibres d’érable de 355-500 μm à 30% en poids. Une augmentation de 52% de la résistance au choc a été réalisée avec l’utilisation de 30% en poids de fibre d’érable (355-500 μm) comparé à ceux produits avec 125-250 μm. D’autre part la production de composites auto-hybrides a été en mesure d'améliorer les propriétés mécaniques comparées aux composites simples. Enfin, une augmentation du module de traction (63%), de la contrainte maximale (17%) et de la densité (17%) a été réalisée lors de l’utilisation d’un ratio de 75/25 de fibre d’érable/chanvre à 20% en poids total de fibre par rapport à la matrice seule.This thesis is divided into six parts. The first part is related to the understanding of the rotomolding process and a description of composite materials based on lignocellulosic fibers. In the second part, a literature review on composites produced by rotomolding is presented. The objective of the third part is to understand the modification of maple fibers in solution by maleated polyethylene (MAPE) and its effect combined with fiber content on the morphological and mechanical properties of the composites. The fourth part studies the effects of fiber size, modification in solution as well as fiber content on the morphological, thermal, physical and mechanical properties of the composites. The fifth part investigates the effect of MAPE modification in solution, fiber content and particle size of maple fibers on the morphological and mechanical properties of selfhybrid composites. Finally, the effect of the surface treatment in solution, the content and the fiber size (maple and hemp) on hybrid composites is presented. The results showed that the fibers (maple and hemp) were successfully modified by MAPE in solution, which improved the interface quality between the matrix and fibers, leading to better mechanical properties. Moreover, the results showed that the effect of fiber size was significant as the tensile modulus increased by up to 73% with the use of 355-500 μm at 30% wt. of maple fiber compared to those produced with 125-250 μm. The production of self-hybrid composites was able to improve the mechanical properties compared to simple composites. An increase in the tensile modulus (63%), tensile strength (17%) and density (17%) was obtained by using a 75/25 ratio of maple/hemp fibers at a total fiber content of 20% wt. compared to the neat matrix.
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Bidegain, Ricardo. "Sur un amendement organo-phosphaté obtenu par traitement aux oxydes d'azote de déchets lignocellulosiques additionnés d'hydroxyapatite : valeur agronomique comparée de ce produit et du compost traditionnel." Toulouse, INPT, 1995. http://www.theses.fr/1995INPT007A.
Abstract:
Lors du traitement aux oxydes d'azote de melanges de dechets organiques et de phosphate apatitique (procede humifert), la solubilisation du phosphate s'accompagne d'une degradation de la matiere organique. Apres l'etude de l'optimisation des parametres du traitement, les substances humiques obtenues sont comparees a celles obtenues par le compostage traditionnel du meme substrat. Dans la premiere partie, des residus de cellulose (papier) ou de lignine (pepins de raisin deshuiles) ont ete traites aux oxydes d'azote en presence de deux doses de phosphore sous forme d'apatite (p#2o#5 6% et 12% de la matiere seche). En presence de cellulose, on observe une degradation de la matiere organique et une solubilisation du phosphore plus importantes qu'en presence de lignine. Les maxima sont obtenus pour le melange cellulose - 12% p#2o#5 (degradation de la matiere organique: 16,5%, solubilisation du phosphore: 26,0%). Dans la deuxieme partie, les substances humiques extraites d'un meme melange initial (sciure de peuplier - sang - farine) composte ou traite par les oxydes d'azote ont ete caracterisees chimiquement. Leurs effets sur le developpement et l'alimentation phosphatee du ray-grass (lolium italicum) ont ete suivis en vases de vegetation. Par rapport a un temoin sans substances humiques, une augmentation de la production de matiere seche allant jusqu'a 18% et une hausse de la quantite de phosphore assimile (de + 20% a 50%) est observee
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Razera, Ilce Aiko Tanaka. "Fibras lignocelulósicas como agente de reforço de compósitos de matriz fenólica e lignofenólica." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-25102007-105313/.
Abstract:
Neste trabalho, fibras lignocelulósicas de diferentes fontes (bananeira e coco) foram utilizadas como agentes de reforço na preparação de compósitos de matriz fenólica e lignofenólica. O fenol, utilizado na formulação da matriz, foi substituído parcial e totalmente por lignina, extraída do bagaço de cana de açúcar por processo Organosolve, na preparação dos termorrígidos lignofenólicos. Os polímeros foram moldados sob compressão e aquecimento controlados. Para caracterização das fibras lignocelulósicas, além da análise da composição, foram utilizadas as seguintes técnicas: difração de raios-X, cromatografia gasosa inversa (IGC), espectroscopia na região de infravermelho (IV), calorimetria exploratória diferencial (DSC), termogravimetria (TG), microscopia eletrônica de varredura (MEV), resistência à tração. Os pré-polímeros (fenólicos e lignofenólicos) foram caracterizados via cromatografia de exclusão por tamanho (SEC), IV, DSC, TG. Os compósitos obtidos foram caracterizados através de ensaios de impacto Izod, análise dinâmico-mecânica (DMA), absorção de água, DSC, TG. Os resultados revelaram que: a substituição total do fenol por lignina é viável; das duas fibras utilizadas como reforço, fibras de coco e banana (não tratadas, ou tratadas com solução alcalina ou ar ionizado), estas últimas apresentaram melhores resultados como reforço de matriz fenólica, possivelmente devido ao mais alto teor de celulose, que é o componente das fibras lignocelulósicas presente nos domínios cristalinos, e que, portanto, exerce a maior influência sobre as propriedades mecânicas destas, e conseqüentemente sobre a ação como reforço em compósitos; em se tratando de compósitos lignofenólicos, principalmente naquele em que fenol foi totalmente substituído por lignina, embora a fibra de coco não tenha boas propriedades mecânicas devido ao baixo teor de celulose, o alto teor de lignina presente neste fibra passou a corresponder a propriedade importantíssima, pois aumentou consideravelmente a afinidade fibra/matriz (também com alto teor de estruturas típicas de lignina). A intensificação das interações na interface possivelmente facilitou a transferência de carga da matriz para a fibra durante o impacto, levando ao material com mais alta resistência ao impacto, dentre os considerados no presente trabalho. Os resultados de absorção de água no geral foram importantes, pois além de indicar a afinidade do material por água, trouxeram também, dentre outras, informações sobre a interface fibra/matriz. No caso dos compósitos preparados a partir de pré-polímeros em que fenol foi totalmente substituído por lignina, os testes de absorção de água também foram importantes no sentido de indicar o melhor processo a ser utilizado na preparação dos pré-polímeros, sendo os resultados condizentes com aqueles obtidos via ensaio de impacto. Deve-se destacar o fato de ter sido possível preparar um compósito com boas propriedades, em que lignina foi usada como macromonômero na preparação da matriz polimérica, sendo esta reforçada com fibras vegetais, ou seja, obteve-se um compósito a partir de alta porcentagem de material oriundo de fontes renováveisIn this work, lignocellulosic fibers from different sources (banana tree and coconut) were used as reinforcing agents in the preparation of phenolic and lignophenolic matrix composites. The phenol used in the matrix formulation was substituted both partially and totally by lignin, extracted from sugarcane bagasse by organosolv process, in the preparation of the lignophenolic thermosets. The composites were molded under controlled pressure and heating. Besides composition analysis, the following techniques were used to characterize the lignocellulosic fibers: X-ray diffraction, inverse gas chromatography (IGC), infrared spectroscopy (IR), differential scanning calorimetry (DSC), thermogravimetry (TG), scanning electron microscopy (SEM), and tensile strength. The prepolymers (phenolic and lignophenolic) were characterized by size exclusion chromatography (SEC), IR, DSC, and TG. The composites obtained were characterized by Izod impact strength, dynamic mechanical analysis (DMA), water absorption, DSC, and TG. The results revealed that: -the total substitution of phenol by lignin is viable; - from the two reinforcing fibers used (banana tree and coconut, both treated and untreated with alkaline solution and ionized air), the former presented the best results as a phenolic matrix reinforcement, possibly due to their larger cellulose content, which is the component of the lignocellulosic fibers present in the crystalline domains. This has a greater influence on the mechanical properties of the fibers, and consequently on their action as composite reinforcement; -concerning the lignophenolic composites, mainly those in which phenol was completely substituted with lignin, although the coconut fibers do not have good mechanical properties due to their low cellulose content, their high lignin content contributed to a very important property, that is, a considerable increase in the affinity between the fiber and the matrix, which also has a high content of typical lignin structures. The intensity of the interactions at the interface may have made the load transfer from the matrix to the fiber during impact easier, resulting in a material with the highest impact strength, when compared to others prepared in the present study; -the water absorption results were generally important as besides information on the affinity of the material for water, they also gave further information on the fiber/matrix interface. In the case of composites prepared from prepolymers whose phenol was totally substituted by lignin, the water absorption tests were also important to indicate the best prepolymer preparation process, which was in agreement with impact assay results. It is important to highlight the fact that it is was possible to prepare a composite with good properties using lignin as a macromonomer in the preparation of a polymeric matrix reinforced with natural fibers, that is to say, with a high percentage of material derived from renewable sources
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Tonoli, Gustavo Henrique Denzin. "Fibras curtas de Eucalipto para novas tecnologias em fibrocimento." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-18022010-142936/.
Abstract:
Este trabalho avalia as vantagens do uso das fibras curtas de polpa de Eucalipto tanto como alternativa às fibras longas de polpa de Pinus, como também para fibras sintéticas, tradicionalmente usadas no reforço de materiais cimentícios. Os efeitos da morfologia (comprimento, largura, fibrilação, conteúdo de finos, número de fibras por grama, etc.) das fibras celulósicas no processamento, no desempenho mecânico e físico e na microestrutura dos compósitos de fibrocimento foram avaliados. Os compósitos foram avaliados antes e após ciclos de envelhecimento acelerado. Fibras de Eucalipto apresentaram melhor dispersão na matriz cimentícia e forneceram maior densidade de fibras em massa ou em volume, em relação às fibras de Pinus. As fibras curtas permitem um reforço efetivo da matriz frágil, diminuindo a propagação das fissuras, o que contribuiu para o melhor desempenho mecânico dos compósitos após envelhecimento. Estes resultados promissores mostram o potencial apresentado pelas fibras curtas de Eucalipto para reduzir custos, em vista da substituição parcial das fibras sintéticas em processos de cura ao ar, e durante o refino da polpa celulósica. O efeito do branqueamento das fibras também foi avaliado, e mostrou que as fibras branqueadas de Eucalipto são mais reativas para se ligarem por pontes de hidrogênio com a matriz cimentícia. Fibras branqueadas melhoraram a interface entre fibra e matriz, embora apresentassem mais sinais de mineralização (re-precipitação de produtos de hidratação dentro das fibras) do que as fibras não-branqueadas. O refino da polpa celulósica foi utilizado para modificar as propriedades morfológicas das fibras de Eucalipto e Pinus. Os resultados mostraram que são necessárias maiores intensidade de refino na polpa de Pinus para obter valores de retenção de sólidos do cimento similares àqueles obtidos com fibras não-refinadas de Eucalipto. O refino aumentou a capacidade das fibras de capturar as partículas minerais, melhorando a aderência das fibras com a matriz. Esta melhor interface entre fibra e matriz melhorou as propriedades mecânicas dos compósitos aos 28 dias de cura, mas os tornou mais frágeis após os ciclos de envelhecimento acelerado. A modificação química da superfície das fibras foi realizada com o objetivo de melhorar as ligações entre fibra e matriz e diminuir a mineralização da fibra dentro dos compósitos. Esta modificação química foi realizada com Metacriloxipropiltri-metoxisilano (MPTS) e Aminopropiltri-etoxisilano (APTS) e mostrou influenciar significativamente a microestrutura dos compósitos. Ciclos de envelhecimento acelerado diminuíram o módulo de ruptura (MOR) e a tenacidade (TE) dos compósitos com fibras não-modificadas e modificadas; entretanto, compósitos reforçados com fibras modificadas com MPTS apresentaram fibras sem produtos de hidratação do cimento em seu interior, enquanto que fibras modificadas com APTS apresentaram acelerada mineralização. Fibras mineralizadas tornam os compósitos mais frágeis após os ciclos de envelhecimento acelerado. Estas observações são, portanto, muito úteis para o entendimento da contribuição de diferentes condições das fibras (composição química, resistência mecânica, morfologia e propriedades de superfície) para os mecanismos de aderência entre fibras e matriz cimentícia, de mineralização das fibras e de degradação dos compósitos de fibrocimento.This work evaluates the advantages of using hardwood short fibre pulp (Eucalyptus) as alternative to softwood long fibre pulp (Pinus) and synthetic fibres, traditionally used in reinforcement of cement based materials. The effects of cellulose fibre morphology (e.g., length, width, fibrillation, content of fines and number of fibres per gram) on the processing, on the mechanical and physical performance and on the microstructure of fibre-cement composites were evaluated. Composites were evaluated before and after accelerated ageing cycles. Eucalyptus pulp fibres were better dispersed in the cement matrix and provided higher number of fibres per unitary weight or volume, in relation to Pinus long fibre pulp. The short reinforcing elements lead to an effective crack bridging of the fragile matrix, which contributes to the improvement of the mechanical performance of the composite after ageing. These promising results show the potential of eucalyptus short fibres for reducing costs by both the partial replacement of expensive synthetic fibres in air curing process and the energy savings during pulp refining. The effects of pulp bleaching were also evaluated, and showed that Eucalyptus bleached fibres are more reactive to bond with the cement matrix by hydrogen bonds. Bleached fibres improved the fibre-matrix interface, although they presented more signals of fibre mineralization. Mechanical refining was used to change the morphological properties of Eucalyptus and Pinus pulps. Results show that high levels of refining were necessary for Pinus pulp to obtain cement retention values similar to those obtained by unrefined Eucalyptus pulp. The mechanical refining increased the capacity of the fibres to capture the mineral particles improving the adherence of the fibres with the matrix. This improved fibre-matrix interface led to better mechanical properties at 28 days of cure, but turned brittle the composites after 200 ageing cycles. The chemical surface modification of cellulose pulp fibres was done in order to improve fibre-matrix bonding and to decrease fibre mineralization into the composite. Surface modification of the cellulose pulps was performed with Methacryloxypropyltri-methoxysilane (MPTS) and Aminopropyltri-ethoxysilane (APTS) and showed significant influence on the microstructure of the composites. Accelerated ageing cycles decreased modulus of rupture (MOR) and toughness (TE) of the composites with unmodified and modified fibres, however composites reinforced with MPTS-modified fibres presented fibres free from cement hydration products, while APTS-modified fibres presented accelerated mineralization. Higher mineralization of the fibres led to higher embrittlement of the composite after accelerated ageing cycles. These observations are therefore very useful for understanding the contribution of the different fibre conditions (chemical composition, mechanical strength, morphology and surface properties) to the mechanisms of fibre-matrix adherence, fibre mineralization and degradation of fibre-cement composites.
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Kosappallyillom, Muraleedharan Praveen. "Studies on O2 plasma modification and fluoroalkyl functional siloxane (FAS) coating effects on natural lignocellulosic coir fibers and development of coir based polypropylene (PP)/ethylene-propylene-diene rubber (EPDM) composites." Thesis, Lorient, 2018. http://www.theses.fr/2018LORIS495/document.
Abstract:
Au cours des dernières années, le développement de matériaux composites avancés fabriqués à partir de fibres naturelles a été principalement axé sur l'obtention de matériaux à haut module et à haute résistance. Cependant, la résistance élevée n'est pas suffisante, car certains des matériaux possèdent une nature fragile (l'allongement à la rupture est faible), et l'un des critères de performance les plus importants devrait être la capacité à absorber l'énergie et à résister aux chocs. La manière dont un matériau composite se déforme et subit des endommagements dépend à la fois des propriétés chimiques et mécaniques de trois constituants de base : les fibres, la matrice et une fine région d'interphase (parfois appelée interface) chargée d'assurer le lien entre matrice et fibre. En raison de leurs propriétés uniques et de leur nature abondante, les fibres à base de cellulose émergent comme un choix privilégié pour les communautés scientifiques, techniques et commerciales qui recherchaient des matériaux durables dans diverses applications. Bien que ces fibres possèdent plusieurs avantages par rapport aux charges synthétiques, l'adhérence entre la fibre et la matrice, la sensibilité à l'humidité et les propriétés au feu restent des domaines difficiles à traiter. Dans ce contexte, une nouvelle technique basée sur la méthode par pulvérisation-séchage-durcissement a permis de fabriquer un revêtement sol-gel hydrophobe sur la surface de la fibre de coco lignocellulosique. La modification de surface des fibres de coco a été effectuée à l'aide d'un plasma oxygène à basse pression suivi d'un enduit sol-gel polymérisable à sec avec un siloxane à fonction fluoroalkyle (FAS). Le prétraitement par plasma a augmenté la concentration effective du réseau FAS sur les fibres de fibre de coco dans le but de créer la surface extrêmement hydrophobe. L'efficacité du traitement plasma et du sol gel FAS sur fibre de coco a été étudiée en utilisant différentes techniques de caractérisation telles que l'analyse de l'angle de contact, l'absorption d'eau, la microscopie électronique à balayage, la microscopie à force atomique et la spectroscopie photoélectronique. Les propriétés mécaniques, morphologiques, rhéologiques et thermiques de différentes formulations de mélanges PP/EPDM ont été étudiées pour trouver la composition optimale du mélange pour la préparation de composites. Les composites résultants à base de polypropylène, d'EPDM et de fibre de coco possèdent des propriétés de résistance aux chocs élevées et des propriétés de traction et de flexion comparables. Les propriétés mécaniques, morphologiques, rhéologiques et thermiques des composites PP/EPDM/Coir ont été étudiées en détail pour examiner la stabilité des compositesIn recent years, the development of advanced high performance composite materials made from natural fibers was mainly focussed on achieving high modulus and strength materials. However, the high strength is not sufficient, as some of the materials possess brittle nature (the overall elongation to fracture is small), and one of the more important performance criterion should be the ability to absorb energy and resist impact loadings. The manner in which a composite material deforms and subjected to fractures depends upon both the chemical and mechanical properties of three basic constituents: the fibers, the matrix and a fine interphase region (sometimes referred to as the interface) responsible for assuring the bond between the matrix and fiber. Due to its unique properties and abundant in nature, lignocellulose based fibers are emerging as a preferred choice for scientific, engineering and commercial communities who were looking for sustainable materials in various applications. Though these fibers possess several advantages over synthetic fillers, adhesion between the fiber and matrix, moisture repellence, flame retardant properties etc are still challenging areas to be addressed. In this context a novel technique based on spray-dry- cure method to establish a hydrophobic sol-gel coating on the lignocellulosic coir fiber surface. The surface modification of lignocellulosic coir fibers was done with the use of low-pressure oxygen plasma, followed by the application of a spray-dry-cure sol–gel coating with the water and oil repellent organic–inorganic hybrid precursor fluoroalkyl-functional siloxane (FAS), with the aim of creating the extremely hydrophobic coir fiber surface. The plasma pre-treatment increased the effective concentration of the FAS network on the lignocellulosic coir fibers. The effectiveness of plasma treatment and FAS sol gel coating on the coir fiber was studied using different characterisation techniques such as contact angle analysis, water absorption studies, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The mechanical, morphological, rheological and thermal properties of different PP/EPDM blend formulations were carried out to find out optimum blend composition for composite preparation. The resulting composites based on polypropylene, EPDM and coir possess high impact strength properties and comparable tensile and flexural properties. The mechanical, morphological, rheological and thermal properties of PP/EPDM/Coir composites were studied in detail to examine the stability of the composites
19
Teixeira, Ronaldo Soares. "Utilização de resíduos sucro-alcooleiros na fabricação de fibrocimento pelo processo de extrusão." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-18112010-112218/.
Abstract:
Este trabalho avalia a utilização de fibras e cinzas de bagaço de cana-de-açúcar em compósitos cimentícios extrudados. Visa o estudo da potencialidade do emprego da fibra e cinza do bagaço da cana-de-açúcar na construção civil, o aproveitamento deste produto em matrizes cimentícias representa uma alternativa para diminuição de gastos com locais para deposição do resíduo evitando a degradação do meio ambiente. A cinza de bagaço de cana-de-açúcar apresenta características pozolânicas, além de garantir uma redução do consumo de cimento. Fibras de bagaço de cana-de-açúcar (FBC) foram classificadas por peneiramento, lavadas em água fervente para reduzir o açúcar residual e foi tratado quimicamente com silicato de sódio e sulfato de alumino com finalidade de proteger as fibras contra a agressão do meio alcalino proporcionado pelo cimento, imobilizar a matéria orgânica e reduzir a absorção de água, diminuindo as variações dimensionais e proporcionar melhor qualidade no compósito, tais como durabilidade e evitar o ataque de microorganismo. As cinzas de bagaço de cana-de-açúcar (CBC) foram queimadas com temperatura e tempo controlado para ter um ótimo grau de amorficidade e conseqüentemente maior reatividade. A moagem também foi efetuada a fim de melhorar a reatividade da cinza. Foi realizada uma série de ensaios de caracterização da CBC. A atividade pozolânica foi averiguada por ensaio condutividade elétrica. O desempenho mecânico e físico e na microestrutura dos compósitos de fibrocimento foram avaliados. Os compósitos foram avaliados antes e após ciclos de envelhecimento acelerado. A extrusão foi utilizada na produção de compósitos cimentícios com geometrias diferenciadas e na produção em pequena escala. Os resultados apresentaram que a fervura da FBC reduziu o açúcar residual e o tratamento químico mineralizou as FBC. As CBC apresentaram valores de sílica elevada. Foram produzidos placas com níveis de reforço entre 0,5% e 5,0% de FBC. Compósitos extrudados com 5% de reforço de FBC com 28 dias de cura apresentaram melhores resultados em tenacidade (TE), devido à maior introdução de FBC no compósito, mas não apresentou diferença entre o tratamento químico. Compósitos extrudados com 5% de reforço de FBC tratada após 200 ciclos de envelhecimento apresentaram maior absorção de água (AA) e porosidade aparente (PA). Esse fato se deve a explicado com a maior hidratação do cimento que ocasionou mineralização drástica da FBC e descolagem da fibra na interface fibra e matriz. Compósito extrudado com 5% de FBC tratada com 28 dias e após 200 ciclos com substituição de cimento por 30% de CBC apresentaram diminuição de módulo de ruptura (MOR) e maior absorção de água (AA). A substituição da matriz (agregado) e a maior relação água/cimento da mistura influenciaram neste resultado. Os resultados indicaram que os compósitos extrudados com reforço de fibra de bagaço de cana e 30% de cinza de bagaço de cana, em substituição ao cimento Portland, podem ser utilizados para produzir elementos construtivos.This study evaluates the use of fibre and ash from sugarcane bagasse in extruded cementitious composites. Aims at studying the potentiality of using fibre and ash from sugarcane bagasse in construction, the use of this product in cementitious matrices represents an alternative to reduce expenses with the waste disposal sites for avoiding environmental degradation. The bagasse ash cane sugar has pozzolanic characteristics and ensures a reduction in cement consumption. Fibres from sugarcane bagasse (FSB) were classified by sieving, washed in boiling water to reduce the residual sugar and has been chemically treated with sodium silicate and aluminum sulphate in order to protect the fibres against the aggression of alkaline provided by the cement, immobilize the organic material and reduce the water absorption, reducing size variations and provide better quality in the composite, such as durability and prevent the attack of microorganisms. The ashes of sugarcane bagasse (ASB) were burned with controlled temperature and time to have a great degree of amorphicity and consequently higher reactivity. The grinding was also performed to improve the reactivity of the ash. We performed a series of tests to characterize the ASB. The pozzolanic activity was determined by electrical conductivity test. The mechanical and physical performance and microstructure of cement composites were evaluated. The composites were evaluated before and after ageing accelerated cycles. Extrusion was used in the production of cementitious composites with different geometries and small scale production. The results showed that boiling FSB reduced the residual sugar and chemically treated to mineralized FSB. The ASB had high amounts of silica. Plates were produced with enhanced levels of between 0.5% and 5.0% of FSB. Composites extruded with 5% of FSB with 28 days of healing showed better results in toughness (TE) due to the increased introduction of FSB in the composite, but no difference between the chemical treatments. Composites extruded with 5% strengthening of FSB treated after 200 ageing accelerated cycles had higher water absorption (AA) and apparent porosity (AP). This fact should be explained with the higher hydration of cement which caused drastic mineralization FSB and off the fibre and fibre-matrix interface. Extruded composite with 5% FBC treated with 28 days and after 200 cycles with replacement of cement by 30% of ASB showed a decrease of modulus of rupture (MOR) and higher water absorption (AA). The substitution matrix (aggregate) and the highest water / cement ratio of the mixture affected this result. The results indicated that the extruded composites reinforced with fibre sugarcane bagasse and 30% ash sugarcane bagasse in Portland cement mortars can be used to produce building elements.
20
Bhadriraju, Vamsi Krishna. "ENZYME-BASED PRODUCTION OF NANOCELLULOSE FROM SOYBEAN HULLS AS A GREEN FILLER FOR RUBBER COMPOUNDING." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1606941104724784.
21
Muraille, Loïc. "Comportement physicochimique des polymères pariétaux à l’échelle supramoléculaire dans des assemblages bioinspirés de la paroi végétale : application à la fibre native." Thesis, Reims, 2014. http://www.theses.fr/2014REIMS039.
Abstract:
En raison des enjeux écologiques actuels, l'utilisation de ressources lignocellulosiques dans l'élaboration de matériaux composites suscite actuellement un intérêt grandissant. Au-delà des applications traditionnelles (papier, panneaux composites, textiles…), les ressources lignocellulosiques constituent une alternative durable aux ressources fossiles pour la production de biocarburant ou d'agrocomposites à base de fibres végétales. Ainsi, si l'on souhaite optimiser les performances de ces nouveaux composites, il est nécessaire de mieux connaitre les propriétés de la fibre et par conséquent réaliser une étude multi-échelle des propriétés physicochimiques et mécaniques des fibres, des polymères constitutifs et de leurs interactions. Dans ce cadre, le premier objectif de la thèse a été de mesurer à l'échelle nanométrique le gradient de propriétés mécaniques et physicochimiques de coupes de fibres végétales par l'intermédiaire de deux techniques utilisant le microscope à force atomique (AFM) visant à cartographier les propriétés nanomécaniques et les caractéristiques spectrales en IR. Puis, pour mieux comprendre le rôle des polymères et de leurs interactions sur les propriétés de la fibre, des systèmes bioinspirés, composés des trois principales classes de polymères pariétaux et de complexité croissante ont été élaborés en veillant à introduire des interactions covalentes et non covalentes entre les polymères, et plus particulièrement entre la lignine et les polysaccharides (cellulose, hémicelluloses)Due to environmental context, the exploitation of lignocellulosic ressources in the elaboration of composite materials has currently a growing interest. Beside traditional uses (paper, textiles…), lignocellulosic ressources constitute a sustainable alternative to fossils ressources for the production of biofuels and fiber-based agrocomposites. However, optimization of the performance of fiber composites requires a multi-scale study of the physicochemical and mechanical properties of the fibers and of their constitutive polymers and their interactions. To this end, the first goal of the thesis is to measure at nanometric scale, the gradient of the mechanical and physicochemical properties of plant fibers using two AFM-based techniques aiming at the mapping of nanomechanical and IR spectral properties. Then, in order to better understand the role of the polymers and of their interactions on the fibers' properties, bioinspired systems have been designed with three main lignocellulosic polymers while achieving in covalent and non-covalent interactions between the polymers (especially between polysaccharides and lignin)
22
Silva, Luiz Claudio Ferreira da. "Utiliza??o de res?duo lignocelul?sico na obten??o de chapa de madeira aglomerada homog?nea e comp?sito refor?ado com fibra de vidro-E." Universidade Federal do Rio Grande do Norte, 2008. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12719.
Abstract:
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This research is about the use of the coconut?s endocarp (nucifera linn) and the waste of derivatives of wood and furniture as raw material to technological use. In that sense, the lignocellulosic waste is used for manufacture of homogeneous wood sheet agglomerate (LHWS) and lignocellulosic load which take part of a polymeric composite with fiber glass E (GFRP-WC). In the manufacturing of the homogeneous wood sheet agglomerate (LHWS), it was used mamona?s resin as waste s agglutinating element. The plates were taken up in a hydraulic press engine, heated, with temperature control, where they were manufactured for different percentage of waste wood and coconuts nuc?fera linn. Physical tests were conducted to determine the absorption of water, density, damp grade (in two hours and twenty-four hours), swelling thickness (in two hours and twenty-four hours), and mechanical tests to evaluate the parallel tensile strength (internal stick) and bending and the static (steady) flexural. The physical test?s results indicate that the LHWS can be classified as bonded wood plate of high-density and with highly water resistant. In the mechanical tests it was possible to establish that LHWS presents different characteristics when submitted to uniaxial tensile and to the static (steady) flexural, since brittle and elasticity module had a variation according to the amount of dry endocarp used to manufacture each trace of LHWS. The GFRP-WC was industrially manufactured by a hand-lay-up process where the fiber glass E was used as reinforcement the lignocellul?sic?s waste as load. The matrix was made with ortofitalic unsaturated polyester resin. Physical and mechanical tests were performed in presence of saturated humidity and dry. The results indicated good performance of the GFRP-WC, as traction as in flexion in three points. The presence of water influenced the modules obtained in the flexural and tensile but there were no significant alteration in the properties analyzed. As for the fracture, the analysis showed that the effects are more harmful in the presence of damp, under the action of loading tested, but despite this, the fracture was well defined starting in the external parts and spreading to the internal regions when one when it reaches the hybrid load
Na presente pesquisam-se a utiliza??o do endocarpo do cocos nuc?fera linn e o res?duo de derivados de madeira e de m?veis como mat?ria-prima para uso tecnol?gico. Nesse sentido, usam-se esses res?duos lignocelul?sico na fabrica??o de chapa de madeira aglomerada homog?nea (CHMC) e, como carga, em comp?sito polim?rico refor?ado com fibra de vidro E (PHFV-MC). Na fabrica??o da chapa de madeira aglomerada homog?nea (CHMC) usou-se a resina ? base de mamona como elemento aglutinante dos res?duos. As chapas foram conformadas em uma prensa hidr?ulica aquecida com controle de temperatura, onde as mesmas foram fabricadas para diferentes percentuais dos res?duos de madeira e do cocos nuc?fera linn. Foram realizados ensaios f?sicos para a determina??o de absor??o de ?gua, densidade, do teor de umidade (em duas horas e vinte e quatro horas), inchamento de espessura (em duas horas e vinte e quatro horas), e ensaios mec?nicos para a determina??o da resist?ncia ? tra??o paralela (ades?o interna) e o ensaio de flex?o est?tica. Os resultados obtidos nos ensaios f?sicos indicam que a CHMC pode ser classificada como chapa de madeira aglomerada de alta densidade e que suporta bem a presen?a de ?gua. Nos ensaios mec?nicos foi poss?vel constatar que a CHMC apresenta caracter?sticas distintas quando submetida ? for?a de tra??o uniaxial e ? flex?o est?tica, uma vez que os m?dulos de ruptura e de elasticidade variaram em fun??o da quantidade do endocarpo seco usado para fabricar cada tra?o da CHMC. A PHFV-MC foi fabricada industrialmente por meio do processo hand-lay-up onde a fibra de vidro-E foi usada como refor?o e os res?duos lignocelul?sicos, como carga. A matriz foi ? base de resina poli?ster ortofit?lica insaturada. Foram realizados ensaios f?sicos e mec?nicos em presen?a de umidade saturada e a seco. Os resultados indicaram um bom desempenho da PHFV-MC, tanto na tra??o quanto na flex?o em tr?s pontos. A presen?a de ?gua influenciou os m?dulos obtidos na flex?o e na tra??o, mas n?o alterou significativamente as propriedades analisadas. Quanto ? fratura, a an?lise mostrou que os efeitos s?o mais danosos em presen?a da umidade, sob a a??o dos carregamentos analisados, mas, apesar disto, a fratura se mostrou bastante caracterizada, iniciando nas regi?es externas e se propagando para as regi?es internas quando atinge a carga h?brida
23
Tétaz, Franck. "Action d'enzymes bactériennes isolées à partir d'un pseudomonas sur des modèles de la lignine de sous-structure [bêta]-O-4 et des préparations de lignines de "bois explosé" : approche par résonance magnétique nucléaire." Grenoble 1, 1988. http://www.theses.fr/1988GRE10052.
24
Kolosick, Paul Christopher. "Interfacial adhesion in lignocellulosic-polypropylene composites." 1992. http://catalog.hathitrust.org/api/volumes/oclc/28706433.html.
Abstract:
Thesis (Ph. D.)--University of Wisconsin--Madison, 1992.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 205-209).
25
Prabawa, Sigit Baktya. "Lignocellulosic fiber plastic composites using sisal fibers from Indonesia." 1996. http://catalog.hathitrust.org/api/volumes/oclc/36287889.html.
Abstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1996.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 71-75).
26
Angelini, Stefania. "Exploitation of Lignocellulosic Biowastes in the Production of Bio-Composites." Tesi di dottorato, 2017. http://www.fedoa.unina.it/11552/1/Angelini_Stefania_XXIX.pdf.
Abstract:
This Ph.D. thesis deals with the exploitation of lignocellulosic industrial biowastes as potential reinforcing agents and flame retardants in sustainable polymer matrices, with the aim of obtaining bio-composites with improved properties and reduced production costs.
The work is based on two main activities, the first one involved a lignocellulosic biowaste (LC) from a second generation bioethanol production process, while lignosulfonates (LS) from pulp and paper industry were used in the second one.
In the first activity, LC was submitted to a thorough morphological, chemical and thermal characterization. Afterwards, it was used as a filler in a biodegradable microbial polymer, poly(3-hydroxybutyrate) (PHB). Blends and compression-moulded bio-composites were prepared. Their rheological, thermal, mechanical properties were studied, along with the biodegradation rate in soil.
In order to identify which of the LC components was responsible for the effects recorded on PHB properties, the biomass was further processed and fractionated to isolate its lignin and polysaccharide constituents. Acid-insoluble lignin (IL) and holocellulose (HC), along with polar and apolar extractive-free solid residues (W, TE) were obtained from the parent LC and used as fillers in PHB in order to prepare bio-based blends and composites. The rheological, thermal, mechanical and crystallization properties of the resulting materials were investigated. This study showed that the use of LC and particularly of IL and HC derivatives, produced a remarkable improvement of PHB processability and crystallization. Such outcomes were relevant in the perspective of replacing oil-based composites with bio-based materials to be exploited in agriculture or packaging.
In the second activity, waste lignosulfonates from pulping process were purified through dialysis in order to remove most of sugar contaminants. Plain and dialysed lignosulfonates were characterized through morphological, chemical and thermal analysis, then used as additives in the production of wood-flour based particleboards (WFP). Their potential fire retardant effect was investigated, and compared to reference WFP containing different amounts of a commercial flame retardant, namely ammonium polyphosphate. The flame retardancy, thermal stability and mechanical performance of the obtained WFP were studied, in order to investigate the effect of lignosulfonates along with their potential synergistic role with ammonium polyphosphate. This activity provided proof of evidence of the possibility to reduce the amount of commercial expensive and toxic flame retardants by partially replacing them with cheap and sustainable lignocellulosic-based biowastes for applications in construction field.
27
Zauscher, Stefan. "Orienting lignocellulosic fibers by means of a magnetic field." Thesis, 1992. http://hdl.handle.net/1957/36066.
Abstract:
Controlling the orientation and spatial distribution of
discontinuous fibers in composite materials enables product
properties to be tailored to anticipated use. Electric
fields are already (albeit rarely) used to affect alignment
in lignocellulosic (LC) fiber composites. The use of
magnetic fields has not, however, been suggested or
explored; this is apparently because LC fibers are
essentially non-magnetic. The approach may offer, however,
some considerable advantages, as long as ferromagnetism may
be imparted to the fibers.
In the present research several fiber modification
processes were considered and two, electroless nickel
plating and spray application of a coating containing nickel
in suspension, were investigated in more depth. The latter
was chosen to render highly engineered, elongated wood
particles responsive to magnetic fields. Individual treated
particles were suspended in viscous, newtonian silicone
fluids and their rotation under the influence of a
controlled magnetic field was video recorded.
The magnetic torque on the particle was, under the
above conditions, directly proportional to the fluid
viscosity, to the particle's angular velocity and to a
characteristic shape constant. The maximum of the specific
magnetic torque (magnetic torque divided by the shape
constant) was found to reflect the influence of field
strength and particle Ni-treatment on rotation. Results
were scaled to an arbitrarily chosen viscosity for
comparison.
The dependencies of the magnetic torque found in the
present research compare with those theoretically predicted
for ellipsoidal and cylindrical bodies. For field strengths
ranging from 0.07T to 0.15T (below magnetic saturation) the
magnetic torque increased almost linearly with increasing
field strength. Magnetic torque was also found to increase
nearly linearly with increasing bulk Ni-concentration (5g/kg
- 50g/kg).
Rotational motion was sometimes impeded at low field
strengths and this was attributed to a permanent magnetic
moment obtained by the particle. A coercive field strength
of 7600A/m supported this hypothesis. Judiciously switched
field polarity increased magnetic torque at small alignment
angles.
The present research indicates that orienting LC fibers
with magnetic fields is possible and promising. To study
dynamics of fiber motion in low viscosity fluids, such as
air, a different experimental method is necessary; however,
dependencies of the magnetic torque found in the present
study still hold true.Graduation date: 1993
28
Tu, Shiau-Rung, and 涂曉蓉. "Processing and Characterization of PLA Composites Reinforced with Lignocellulosic Fiber Prepared from Wood Particles." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/47pm5a.
Abstract:
碩士國立臺北科技大學
有機高分子研究所
97
Poly (lactic acid) (PLA) is a commercially available biodegradable polymer derived from renewable resources. PLA offers a potential alternative to petrochemical-based plastics in many applications; however, the relatively high price, brittleness, and low toughness of PLA limit it wide application, with renewable biofiber provides a convenient approach to tailor the material cost and engineer the material properties. In this study, environmentally friendly biocomposites, composed of PLA and wood fibers derived from Acacia confusa wood powders, were prepared with a twin screw extruder. The wood powder were either used in their native state or subjected to various treatments prior to blending. The treatments used were steam explosion (SE) at 170℃or 210℃, followed by either hot water wash or the alkaline peroxide (AP) treatment. The mechanical and thermal properties of the resulting composites were investigated as a function of wood powder treatment methods and wood fiber contents (5 wt%, 10 wt%, 20 wt%), while the microstructures of the composites were examined with SEM. Results show that the incorporation of steam-exploded wood powders significantly improved the impact strength. Compared with the pure PLA, the impact strength was doubled when a fiber content of 20 wt% was used, and the wood powders received the combined SE (at 170℃) and AP treatment. The dynamic mechanical analysis also indicates that the glass transition temperature (Tg) and the storage modulus increased with the addition of fibers prepared by steam explosion.
29
Kuo, Jin-Rong, and 郭晉榕. "Carbon-Silicon Composites Prepared from Recycled Silicon and Lignocellulose for Negative Electrodes of Li-ion Batteries." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/uuncbk.
Abstract:
碩士國立臺灣大學
化學工程學研究所
105
Silicon has the potential to replace the graphite as the anode material for Li-ion batteries due to its high specific capacity and appropriate working voltage. However, the dramatic volume change during the Li-ion insertion and extraction has caused the poor cyclic stability. To improve the cyclic stability of Si anode, we embedded Si into a carbon matrix to form a Si-C composites. In this study, we employed the silicon particles recovered from the silicon ingot slicing slurries and the biomass (lignin and lignocellulose), which are by-products of pulp industry, to fabricate negative electrodes for lithium ion battery. Lignin or lignocellulose would be well mixed with Si particles by magnetic stirring and ultrasonication and then undergo a pyrolysis process to form Si-C composites. Due to different carbonaceous precursors, the composites have different structures. The pyrolyzed lignocellulose formed an interconnected structure with Si particles, which provides extra space to accommodate Si volume variation. The composite electrode exhibits outstanding cycle performance for capacity retention up to 83.4% after 51 cycles at 300 mAh/g. On the other hand, the Si particles in lignin-Si composites are coated with a carbon layer, and the layer can not only suppress the volume change but also increase the contact electronic conductivity. Besides, the SEI layer on the carbon surface would be stable. It also showed excellent electrochemical performance with an initial charge capacity up to 2286 mAh/g and retaining 880 mAh/g after 51 cycles at 300 mA/g. We hope that the utilization of renewable sources and industrial Si slurry as battery materials can be improved and applied in energy storage application.
30
Simões, Alexandre Filipe Vaz. "Desenvolvimento sustentável de compósitos reforçados com resíduo de cerveja." Master's thesis, 2021. http://hdl.handle.net/10316/97941.
Abstract:
Dissertação de Mestrado em Química apresentada à Faculdade de Ciências e TecnologiaAo longo dos anos, têm aumentado os esforços para tornar o mundo mais sustentável devido à crescente preocupação ambiental e escassez de fontes não renováveis, através do reaproveito de subprodutos industriais e produção de materiais ecológicos. As fibras lignocelulósicas devido à sua abundância e elevado potencial como fonte renovável têm gerado interesse para a produção de novos materiais sustentáveis. Assim, surge o interesse do aproveitamento do principal subproduto da indústria, o resíduo de cervejeira, como fibras lignocelulósica, para a produção de compósitos. Neste trabalho, numa primeira fase procedeu-se à caraterização de dois tipos de resíduos de cerveja com diferentes origens: resíduo cerveja Práxis e resíduo de cerveja Super Bock. Verificou-se que dependendo da origem de cerveja produzida, existe uma variação quantitativa na composição do resíduo de cerveja. As fibras lignocelulósicas podem conferir um reforço para compósitos, e por isso foram estudados compósitos com várias matrizes poliméricas e biopoliméricas reforçados com resíduo de cerveja. As matrizes utilizadas nos compósitos foram o polietileno de baixa densidade reciclado, polibutileno adipato co-tereftalato com amido termoplástico, poliácido láctico e polibutileno succinato, e foi estudada a influência da adição de várias proporções do resíduo de cerveja, nas propriedades físico-químicas do compósito. A matriz e o reforço são os componentes principais dos compósitos, sendo que o desempenho do compósito é influenciado pela interação matriz-reforço. Para garantir uma boa adesão e assegurar a compatibilidade foi avaliado a adição de um agente de acoplamento verde à base de óleo alimentar usado, o uso de um surfactante (o SDS), e o uso de PBS-AM. Para estudar as propriedades dos compósitos realizou-se análises de reometria de torque, ensaios mecânicos de tração onde se obteve a resistência à tração, deformação na rutura e módulo de Young , e testes de absorção e solubilidade em água. Os resultados revelam que compósitos com diferentes matrizes, têm diferentes interações com as fibras e mostram diferentes propriedades. A adição do agente de acoplamento verde aos compósitos melhora a interação matriz-fibra nos compósitos de polieteileno polietileno de baixa densidade reciclado, poliácido lático e no PBS.
Over the last years, efforts have increased to make the world more sustainable due to the growing environmental concern and scarcity of non-renewable sources, through the reuse of industrial by-products and production of ecological materials. Due to their abundance and high potential as a renewable source, lignocellulosic fibers have generated interest in the production of new sustainable materials. Thus, there is an interest in using the industry's main by-product for beer industry, beer residue, such as lignocellulosic fibers, for the production of composites.In thea first phase of this work, two types of beer residues with different origins were characterized: Praxis beer residue and Super Bock beer residue. It was found that depending on the origin of the beer produced, there is a quantitative variation in the composition of the beer residue.Lignocellulosic fibers can provide reinforcement to reinforce composites, and therefore composites with various polymeric and biopolymeric matrices reinforced with beer residue have been studied. The matrices used in the composites are recycled low-density polyethylene, polybutylene adipate co-terephthalate with thermoplastic starch, polylactic acid and polybutylene succinate, and the influence of the addition of various proportions of beer residue on the physicochemical properties of the composite is was studied. The matrix and the reinforcement are main components of the composites, and the performance of the composite depends on the interaction between them, and to ensure good adhesion and ensure compatibility, the addition of a green coupling agent based on used cooking oil was evaluated. To study the properties of the composites, analyzes of torque rheometry, mechanical tensile tests were carried out, where the tensile strength, deformation at break and Young's modulus were obtained, as well as absorption and solubility water tests. The results reveal that composites with different matrices have different interactions with fibers. The improvement by adding the green coupling agent is seenwas observed in the composites of with recycled low density polyethylene, polyethylene, polylactic acid and PBS.