Добірка наукової літератури з теми "Modification de lignine"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Modification de lignine".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Статті в журналах з теми "Modification de lignine"
1
Chatonnet, Pascal, Jean-Noël Boidron, Denis Dubourdieu, and Monique Pons. "Evolution de certains composés volatils du bois de chêne au cours de son séchage premiers résultats." OENO One 28, no. 4 (December 31, 1994): 359. http://dx.doi.org/10.20870/oeno-one.1994.28.4.1720.
Повний текст джерелаАнотація:
<p style="text-align: justify;">Pendant le séchage des merrains sur parc à l'air libre, on assiste à une profonde modification de la composition chimique et du profil aromatique du bois de chêne. La teneur en eugénol, en aldéhydes phénols et en Β-méthyl-y-octalactone augmente régulièrement pendant le vieillissement du bois. Principalement sous forme trans au début du séchage, la Β-méthyl-y-octalactone s'accumule finalement sous la forme cis plus aromatique. Dans le même temps, on observe également une accumulation importante du précurseur inodore de Β-méthyl-y-octalactone. L'intervention des micro-organismes fréquemment isolés sur le bois en cours de séchage naturel sur la formation de composés aromatiques a été étudiée. La culture de diverses moisissures isolées de bois en cours de séchage naturel sur extraits de bois et directement sur sciure de chêne aboutit dans tous les cas à une forte diminution des teneurs en aldéhydes phénols, notamment de la vanilline. En effet, tous les micro-organismes étudiés (<em>Penicilium sp., Trichoderma sp., Aureobasidium sp.</em>) sont incapables de dégrader la lignine car ils ne possèdent pas d'activité ligninase. En revanche, ces champignons possèdent une forte activité oxydo-réductase capable de réduire la vanilline en alcool vanillique inodore. En conséquence, les aldéhydes phénols apparaissant au cours du séchage naturel du merrain ne dérivent pas d'une attaque enzymatique mais plus vraisemblablementde l'acidolyse et de l'oxydation chimique de la lignine du bois. Le stockage du bois à l'air libre en présence d'eau et d'oxygène doit permettre une évolution favorable de son potentiel aromatique tant que la vanilline et la cis Β-méthyly-octalactone s'accumulent.</p>
2
Vikman, Minna, Olesya Fearon, and Anna Kalliola. "Biodegradation of alkali-O2 oxidized lignins used as dispersants." BioResources 17, no. 4 (September 13, 2022): 6079–93. http://dx.doi.org/10.15376/biores.17.4.6079-6093.
Повний текст джерелаАнотація:
Large quantities of lignin are produced as by-streams via chemical pulping and emerging biorefinery processes. These lignins are typically water-insoluble; however, they can be converted into a water-soluble form by chemical modifications. A novel LigniOx technology solubilizes lignin using alkali-O2 oxidation. The product can be used for bio-based dispersants. This study evaluated the biodegradability of alkali-O2 oxidized kraft, organosolv, and hydrolysis lignin. The oxidized lignins exhibited higher biodegradation in soil and in aquatic environments in comparison to a commercial kraft lignin and a commercial lignosulfonate. In soil, the biodegradabilities of oxidized lignins were 19 to 44%, whereas the reference lignins exhibited only 5 to 12% conversion to CO2. Biodegradation of the oxidized lignins and references in the aquatic environment increased in a similar order as in the soil environment, although the degradation in each sample was slightly smaller than in the soil. The improved biodegradability of the oxidized lignins was due to the altered chemical structure of lignin. Compared to the untreated lignin, the oxidized lignin contained structures formed in aromatic ring opening reactions, making the lignin more accessible to microbial degradation. In addition, the oxidized lignin contained carbon originating from small organic compounds, which are easily biodegradable.
3
Wang, Yun-Yan, Xianzhi Meng, Yunqiao Pu, and Arthur J. Ragauskas. "Recent Advances in the Application of Functionalized Lignin in Value-Added Polymeric Materials." Polymers 12, no. 10 (October 3, 2020): 2277. http://dx.doi.org/10.3390/polym12102277.
Повний текст джерелаАнотація:
The quest for converting lignin into high-value products has been continuously pursued in the past few decades. In its native form, lignin is a group of heterogeneous polymers comprised of phenylpropanoids. The major commercial lignin streams, including Kraft lignin, lignosulfonates, soda lignin and organosolv lignin, are produced from industrial processes including the paper and pulping industry and emerging lignocellulosic biorefineries. Although lignin has been viewed as a low-cost and renewable feedstock to replace petroleum-based materials, its utilization in polymeric materials has been suppressed due to the low reactivity and inherent physicochemical properties of lignin. Hence, various lignin modification strategies have been developed to overcome these problems. Herein, we review recent progress made in the utilization of functionalized lignins in commodity polymers including thermoset resins, blends/composites, grafted functionalized copolymers and carbon fiber precursors. In the synthesis of thermoset resins such as polyurethane, phenol-formaldehyde and epoxy, they are covalently incorporated into the polymer matrix, and the discussion is focused on chemical modifications improving the reactivity of technical lignins. In blends/composites, functionalization of technical lignins is based upon tuning the intermolecular forces between polymer components. In addition, grafted functional polymers have expanded the utilization of lignin-based copolymers to biomedical materials and value-added additives. Different modification approaches have also been applied to facilitate the application of lignin as carbon fiber precursors, heavy metal adsorbents and nanoparticles. These emerging fields will create new opportunities in cost-effectively integrating the lignin valorization into lignocellulosic biorefineries.
4
Suota, Maria Juliane, Débora Merediane Kochepka, Marlon Gualberto Ganter Moura, Cleverton Luiz Pirich, Mailson Matos, Washington Luiz Esteves Magalhães, and Luiz Pereira Ramos. "Lignin functionalization strategies and the potential applications of its derivatives – A Review." BioResources 16, no. 3 (July 12, 2021): 6471–511. http://dx.doi.org/10.15376/biores.16.3.suota.
Повний текст джерелаАнотація:
Lignin is one of the most important and widespread carbon sources on Earth. Significant amounts of lignin are delivered to the market by pulp mills and biorefineries, and there have been many efforts to develop routes for its valorization. Over the years, lignin has been used to produce biobased chemicals, materials, and advanced biofuels on the basis of its variable functionalities and physicochemical properties. Today, lignin’s applications are still limited by its heterogeneity, variability, and low reactivity. Thus, modification technologies have been developed to allow lignin to be suitable for a wider range of attractive industrial applications. The most common modifications used for this purpose include amination, methylation, demethylation, phenolation, sulfomethylation, oxyalkylation, acylation or esterification, epoxidation, phosphorylation, nitration, and sulfonation. This article reviews the chemistry involved in these lignin modification technologies, discussing their effect on the finished product while presenting some market perspectives and future outlook to utilize lignin in sustainable biorefineries.
5
Chatonnet, Pascal, Jean-Noël Boidron, and Monique Pons. "Incidence du traitement thermique du bois de chêne sur sa composition chimique. 2e partie : évolution de certains composés en fonction de l'intensité de brûlage." OENO One 23, no. 4 (December 31, 1989): 223. http://dx.doi.org/10.20870/oeno-one.1989.23.4.1722.
Повний текст джерелаАнотація:
<p style="text-align: justify;">Au-delà de son action de cintrage, le chauffage du bois de chêne provoque une thermodégradation de certains de ses composants. Les auteurs étudient l'influence de l'intensité de brûlage du bois de chêne sessile <em>Quercus sessilis</em> sur certains composés extractibles. Afin de se rapprocher des conditions d'extraction par un vin, le bois brûlé à différents degrés est placé au contact d'une solution hydroalcoolique modèle.</p><p style="text-align: justify;">La thermolyse des principaux polymères pariétaux du bois, produit de nombreux composés volatils et odorants (aldéhydes furaniques, phénols volatils, aldéhydes phénols, phényl cétones). La concentration en β-méthyl-y-octalactone augmente notablement avec le chauffage du bois et simultanément les tanins hydrolysables sont en partie dégradés.</p><p style="text-align: justify;">La chauffe légère ne produit que de faibles variations. La chauffe moyenne correspond au maximum de synthèse de la majorité des composés aromatiques étudiés. A partir et au-delà de la chauffe forte, les réactions de thermodégradation, mais très vraisemblablement aussi une modification de la structure de la lignine vers une forme moins réactive, entraînent une diminution de l'ensemble des composés extractibles.</p>
6
Lauberte, Liga, Gabin Fabre, Jevgenija Ponomarenko, Tatiana Dizhbite, Dmitry V. Evtuguin, Galina Telysheva, and Patrick Trouillas. "Lignin Modification Supported by DFT-Based Theoretical Study as a Way to Produce Competitive Natural Antioxidants." Molecules 24, no. 9 (May 9, 2019): 1794. http://dx.doi.org/10.3390/molecules24091794.
Повний текст джерелаАнотація:
The valorization of lignins as renewable aromatic feedstock is of utmost importance in terms of the use of sustainable resources. This study provides a deductive approach towards market-oriented lignin-derived antioxidants by ascertaining the direct effect of different structural features of lignin on the reactivity of its phenolic OH groups in the radical scavenging reactions. The antioxidant activity of a series of compounds, modeling lignin structural units, was experimentally characterized and rationalized, using thermodynamic descriptors. The calculated O–H bond dissociation enthalpies (BDE) of characteristic lignin subunits were used to predict the modification pathways of technical lignins. The last ones were isolated by soda delignification from different biomass sources and their oligomeric fractions were studied as a raw material for modification and production of optimized antioxidants. These were characterized in terms of chemical structure, molecular weight distribution, content of the functional groups, and the antioxidant activity. The developed approach for the targeted modification of lignins allowed the products competitive with two commercial synthetic phenolic antioxidants in both free radical scavenging and stabilization of thermooxidative destruction of polyurethane films.
7
Nadányi, Richard, Aleš Ház, Anton Lisý, Michal Jablonský, Igor Šurina, Veronika Majová, and Andrej Baco. "Lignin Modifications, Applications, and Possible Market Prices." Energies 15, no. 18 (September 7, 2022): 6520. http://dx.doi.org/10.3390/en15186520.
Повний текст джерелаАнотація:
Lignin is the second most abundant biopolymer in the world. Due to its complex structure, lignin can be considered a valuable source of energy and different chemicals. In addition, using different reactive sites on lignin, it is possible to prepare different value-added products, such as resins, polyurethanes, and many more. Different functional groups are presented on the lignin macromolecule and can be modified via different pathways. Hydroxyl groups are the most promising reactive sites for lignin modifications. Both modified and unmodified lignins could be used for preparing different biomaterials. This paper shows several possible applications of lignin. The main goal of this publication is to show the possible valorization of lignin in different value-added products throughout the actual market prices of non-biobased materials. This review proves that lignin has unquestionable advantages in material technology and can replace different substances which will lead to a higher potential market value of lignins and could create new bio-based materials compared with the actual prices of commercially available materials. Nowadays, it is easier to use lignin as an energy source even though a lot of lignin modifications and conversion processes are still under development and need more time to become more relevant for industrial applications. Information in the presented paper should reveal to the reader the importance and economic benefits of using lignin as a value-added compound in different applications.
8
Duarte, A. P., D. Robert, and D. Lachenal. "Eucalyptus globulus Kraft Pulp Residual Lignin. Part 2. Modification of Residual Lignin Structure in Oxygen Bleaching." Holzforschung 55, no. 6 (November 6, 2001): 645–51. http://dx.doi.org/10.1515/hf.2001.105.
Повний текст джерелаАнотація:
Summary Residual lignins were isolated from unbleached and oxygen-bleached Eucalyptus kraft pulps by acid hydrolysis. The structural changes and degradation of residual lignin occurring during kraft pulping and oxygen bleaching were followed and identified by elemental analysis, residual carbohydrate analysis, molecular mass distribution, as well as qualitative and quantitative solution 13C NMR. The dissolved lignins in the kraft cooked and oxygen bleached liquors were also studied and compared with the corresponding residual lignins. Milled wood lignin treated under acid hydrolysis conditions served as a reference for the structural comparison. The results show that etherified syringyl structures were quite resistant towards degradation in the oxygen bleaching, causing little depolymerisation in residual lignin and a small increase in carboxylic acid content, but producing appreciable amounts of saturated aliphatic methylene groups.
9
Younesi-Kordkheili, Hamed, and Antonio Pizzi. "A Comparison among Lignin Modification Methods on the Properties of Lignin–Phenol–Formaldehyde Resin as Wood Adhesive." Polymers 13, no. 20 (October 12, 2021): 3502. http://dx.doi.org/10.3390/polym13203502.
Повний текст джерелаАнотація:
The research aim of this work is to determine the influence of lignin modification methods on lignin–phenol–formaldehyde (LPF) adhesive properties. Thus, glyoxal (G), phenol (P), ionic liquid (IL), and maleic anhydride (MA) were used to modify lignin. The modified lignins were used for phenol substitution (50 wt%) in phenol–formaldehyde adhesives. The prepared resins were then used for the preparation of wood particleboard. These LPF resins were characterized physicochemically, namely by using standard methods to determine gel time, solids content, density, and viscosity, thus the physicochemical properties of the LPF resins synthesized. The panels dimensional stability, formaldehyde emission, bending modulus, bending strength, and internal bond (IB) strength were also measured. MA-modified lignin showed by differential scanning calorimetry (DSC) the lowest temperature of curing than the resins with non-modified lignin and modified with IL, phenolared lignin, and glyoxal. LPF resins with lignin treated with maleic anhydride presented a shorter gel time, higher viscosity, and solids content than the resins with other lignin modifications. Equally, the particleboard panels prepared with LPF resins with maleic anhydride or with ionic liquid had the lowest formaldehyde emission and the highest mechanical strength among all the synthesized resins. The dimensional stability of all panels bonded with modified lignin LPF resins presented no difference of any significance.
10
Bujanovic, Biljana, Sally A. Ralph, Richard S. Reiner, and Rajai H. Atalla. "Lignin modification in the initial phase of softwood kraft pulp delignification with polyoxometalates (POMs)." Holzforschung 61, no. 5 (August 1, 2007): 492–98. http://dx.doi.org/10.1515/hf.2007.102.
Повний текст джерелаАнотація:
Abstract Commercial softwood kraft pulp with kappa number 30.5 (KP30.5) was delignified with polyoxometalates (POM, Na5(+2)[SiV1(-0.1)MoW10(+0.1)O40]), and POM-treated kraft pulp of kappa number 23.6 was obtained (KPPOM,23.6). Residual lignin from pulps was isolated by mild acid hydrolysis and characterized by analytical and spectral methods to gain insight into lignin reactions taking place during the initial delignification phase. Lignin from POM-delignified pulp was isolated in lower yield. Comparative analysis of residual lignins (RL-KP30.5, RL-KPPOM,23.6) showed that POM leads to products enriched in carbonyl/carboxyl groups and carbohydrates. POM lignins have a lower molecular mass and a lower content of phenolic hydroxyl and methoxyl groups. Based on these results and FTIR spectra, we suggest that aromatic ring cleavage and quinone formation occur during POM delignification. The degree of lignin-cellulose association increases after POM delignification. Lignin-cellulose association was found to be partially unstable under mild alkaline conditions, as residual lignin isolated after alkaline extraction of KPPOM,23.6 pulp (RL-KPPOM/NaOH) exhibited lower glucose content, higher Klason lignin content, and less extraneous material.
Дисертації з теми "Modification de lignine"
1
Kozik, Patrycja. "Prépolymères à base de lignines pour la rigidification de formulations d'élastomères." Thesis, Reims, 2016. http://www.theses.fr/2016REIMS023.
Повний текст джерелаАнотація:
Le cadre industriel de ce projet est de trouver une alternative à la résine phénol-formaldéhyde (RFP) et à son durcisseur, utilisée actuellement en pneumatique pour améliorer les performances aussi bien des compositions de caoutchouc que celles des produits semi-finis. Un des aspects essentiels de la pneumatique est d’augmenter la rigidité à faible déformation des pneus sans augmenter l'hystérésis des élastomères durcis chargés de noir de carbone. Ainsi, l'objectif de ce travail de thèse est de proposer un système thermodurcissable alternatif aux résines RFP actuelles. Ce nouveau système doit être riche en carbone renouvelable et doit être chimiquement modifié au moyen de procédés écologiques. La lignine a été choisie comme source de carbone renouvelable. Une étude préliminaire a souligné les potentialités d'une classe de lignines époxy pour l'application visée. Notre approche consiste en la conception de lignines modifiées par des époxy par une méthode originale évitant l'utilisation de l'épichlorhydrine suivie de son durcissement par des agents de réticulation appropriés. Des tests préliminaires avec un composé modèle de lignine ont donné la gamme des composés époxy et les conditions à tester pour la réaction avec la lignine. Les expériences avec la lignine ont alors confirmé le potentiel de l’ester diglycidylique de l’acide 4, 5-époxytetrahydrophthalique, un composé époxy contenant à la fois un groupement cycloaliphatique et deux types de groupements époxy glycidyliques, comme alternative à l'épichlorohydrine pour la préparation de lignines modifiées. Dans les conditions que nous avons définies, la réaction donne des prépolymères de type lignine-époxy sous forme de poudre avec un niveau d’époxydation de 1,2 mol/kg déterminé par spectroscopie FTIR. La série de tests effectuée sur des mélanges de caoutchouc a montré que la nouvelle lignine époxy associée à la p-xylylènediamine peut être mélangée avec succès avec le caoutchouc naturel et peut atteindre les propriétés de notre mix de référenceThe industrial framework of this project is the substitution of phenol formaldehyde resin (RFP) and its methyl donor hardener currently used for improving the performances of rubber compositions of tires or semi-finished products for tires. A critical aspect is the need for an increase of rigidity at low deformation without enhancement of the hysteresis of the cured elastomers filled with carbon black. The specific aim of this PhD work was to propose an alternative thermosetting system to the current RFP resins. This new system should be rich in renewable carbon and chemically modified by environmentally friendly processes. Lignin was chosen as the source of the renewable carbon. A preliminary study emphasized the potentialities of a class of epoxy-modified lignins for the targeted application. The main approach was the design of epoxy modified lignin to be obtained by an original method avoiding the use of epichlorohydrine and to be subsequently cured by appropriate cross-linkers. A preliminary screening with a lignin model compound gave the range of the epoxy compounds and the conditions to be tested for the reaction with lignin. Then various experiments with lignin confirmed the potential of 4, 5-epoxytetrahydrophthalic acid diglycidylester, an epoxy compound containing both one cycloaliphatic and two glycidyl type of epoxy groups, as an alternative for epichlorohydrine for the preparation of modified lignin. In the conditions we have defined, the reaction yielded epoxy lignin-based prepolymers as a powder with epoxy level as high as 1,2 mol/kg determined by FTIR spectroscopy. The series of evaluation campaigns in rubber blends showed that the new epoxy-modified lignin associated with p-xylylenediamine can be successfully mixed with natural rubber and enable to reach the properties of our reference mix
2
Michel, Philippe. "Modification chimique de la lignine : synthèse radicalaire et caractérisation de copolymères, lignine beta méthacrylate de méthyle." Bordeaux 1, 1989. http://www.theses.fr/1989BOR10592.
Повний текст джерелаАнотація:
Dans l'optique d'une recherche de moyens de valorisation de la lignine, residu de diverses operations industrielles visant a la recuperation des derives cellulosiques, l'etude a ete divise en trois parties: 1) une approche generale du probleme passe, d'abord, en revue les differents moyens d'extraction et de caracterisation du materiau ainsi que les utilisations qui en ont ete proposees; 2) la transformation en macroamorceur de processus radicalaires, d'un echantillon de lignine issu de l'autohydrolyse, puis de l'hydrolyse enzymatique de lots de paille de ble, est ensuite envisagee, en s'appuyant sur le comportement de composes modeles; 3) etudiee dans la derniere partie, la mise en uvre du macroamorceur permet d'acceder a des copolymeres (lignine-b-methacrylate de methyle); le materiau correspondant presente, entre autres proprietes, une adhesivite interessante sur des eprouvettes de bois
3
Schorr, Diane. "Caractérisation et modification des lignines industrielles." Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25365.
Повний текст джерелаАнотація:
Les lignines sont des polymères naturels et renouvelables. C’est le polymère le plus abondant sur la terre après la cellulose. De nos jours, les lignines sont sous-exploitées et seulement 2 % de la lignine est valorisée par an, leur application capital restant comme combustible dans les industries papetières pour la production d'énergie. Au Québec, 130 000 tonnes de liqueur noire contenant de la lignine pourraient être extraites par an afin de les valoriser, sans perturber la production dans ces industries papetières. Sa valorisation pourrait contribuer à créer de nouveaux produits à valeur ajoutée tels que les biocomposites avec une matrice de polyéthylène, polystyrène recyclé ou encore le bois. Ces nouveaux produits de ces industries pourraient améliorer la situation économique dans ce domaine, mais aussi pourraient apporter de nouvelles connaissances dans le domaine des écomatériaux tout en contribuant à la diminution des gaz à effet de serre en favorisant le produit naturel contre le produit de synthèse. Les structures des lignines diffèrent selon certains paramètres (origine, le processus d'isolation ...). Dans ce projet, deux lignines Kraft seront précipitées à partir de liqueur noire de deux industries papetières québécoises en utilisant du dioxyde de carbone comme réactif. Ces lignines seront purifiées et comparées analytiquement à d’autres lignines; une lignine Kraft commerciale, une lignine pyrolytique et une lignine Protobind Soda 2400. Connaissant la structure des lignines, il sera plus facile de les modifier. Les lignines Kraft ont été estérifiées avec l'anhydride maléique et l'anhydride succinique et comparée aux lignines non modifiées par plusieurs techniques d'analyse telles que FT-IR, TGA, DSC, RMN. Les lignines Wayagamack maléatées et non maléatées ont été incorporées dans un biocomposite de polystyrène recyclé et les propriétés mécaniques et thermiques ainsi que la morphologie ont été étudiées. Les composites avec la lignine non modifié ont montré de bonnes propriétés mécaniques et thermiques par rapport au composite avec la lignine maléate où la lignine maléatée était pourtant compatible avec le polystyrène recyclé. Les lignines Windsor non estérifiée et succinate ont été utilisées en tant que liant dans un panneau de bois et leurs propriétés mécaniques ont également été étudiées. Les résultats ont montré les meilleures propriétés mécaniques pour le panneau de bois contenant de la lignine Kraft non modifié. Les réactions de condensation de la lignine Kraft au cours de la compression à chaud du panneau améliorerait la solidité du panneau contrairement à des réactions d'estérification qui pourraient avoir lieu entre la lignine estérifié et les hydroxyles de bois. Mots clés : Liqueur noire, Lignine, Procédé Kraft, Estérification, Caractérisation, Composite, Valorisation, polystyrène, bois.Lignins are renewable and natural polymers. It is the most abundant polymer on the earth after cellulose. Nowadays, lignins are not fully exploited and only 2% of lignin is valorised per year, their principal application remaining as a combustible in pulp industries for energy production. In Quebec, 130000 tons of black liquor containing lignin could be available from Kraft industry, per year, in order to valorise them, without disturbing the mill production. Its valorisation could contribute to create new value added products like bio composites with a matrix of polyethylene, recycled polystyrene or even wood. These new products of these industries could improve the economic situation in this field, but also could bring new knowledge in the eco materials field, in contributing of the decrease of greenhouse gases in favoring the natural product against the synthetic product. Lignin structure is different depending on several parameters (origin, isolation process…). In this project, two Kraft lignins will be precipitated from black liquor of two Quebecoise paper industries using carbon dioxide as the reagent. These lignins will be purified and compared analytically to others lignins; one Kraft softwood commercial lignin, one pyrolytic lignin and one Soda lignin Protobind 2400. With the knowledge of the Kraft lignin structure, it will be easier to modify these lignins. The esterified Kraft lignins with maleic anhydride and succinic anhydride will be compared to the unmodified lignin according to several analytical technical as FT-IR, TGA, DSC, NMR. Maleated and non modified Wayagamack lignins were incorporated in biocomposite of recycled polystyrene and the mechanical and thermal properties and the morphology were studied. The composite with non modified lignin showed good mechanical and thermal properties compared to the composite with maleated lignin where the maleated lignin was still compatible with the recycled polystyrene The Windsor succinated and non modified lignin were used as a binder in a wood panel and their properties were also studied. The results showed the best mechanical properties for the wood panel containing non modified Kraft lignin. Condensation reactions of Kraft lignin during the hot-pressing of the panel improve the solidity of the panel unlike esterification reactions that could take place between esterified lignin and the wood hydroxyls. Key words: Black liquor, Lignin, Kraft process, Characterisation, Esterification, Composite, Valorization, Polystyrene, Wood.
4
Bardot, Fanny. "Modification de lignines issues de la fabrication des pâtes lignocellulosiques en vue de leur incorporation dans des formulations d'encres." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI100.
Повний текст джерелаАнотація:
L’originalité de ce travail est d’utiliser de la lignine, une macromolécule aromatique extraite de la biomasse lignocellulosique, en remplacement de résines pétrosourcées pour la formulation d’encres à destination de l’emballage alimentaire. Différentes modifications chimiques ont été réalisées sur des lignines commerciales afin de les rendre compatibles avec les composants utilisés dans la formulation des encres. Les réactifs et les procédés mis en place ont été choisis afin de limiter l’impact environnemental sur l’ensemble de la chaîne de valeur. Les modifications chimiques ont été mesurées par différentes techniques analytiques telles que la GPC SEC pour la distribution des masses molaires et la spectrométrie RMN et FTIR pour la mesure des groupements fonctionnels de la lignine. Les propriétés des encres obtenues ont été caractérisées par des mesures rhéologiques et colorimétriques (système CIE L*a*b*) sur des essais d’impression. Parmi les résultats notables, des changements au niveau de l’équilibre hydrophile/hydrophobe ont été particulièrement remarqués. Qui plus est, les encres à base de lignines modifiées chimiquement ont permis une amélioration du gamut de couleur par rapport à celles contenant de la lignine brute. A l’issue de ces travaux, deux applications ont été proposées Des encres biosourcées à base de lignine qui répondent à la majorité des exigences industrielles ont été formulées. De plus, une formule d’enduction à base de lignine modifiée améliorant les propriétés barrières des papiers recyclés a été développée avec succèsThe originality of this work is to use lignin, an aromatic macromolecule from lignocellulosic biomass, in replacement of petroleum-based resins for the formulation of inks for food contact packaging applications. Different chemical modifications were carried out on commercial lignins, in order to make them compatible with the ink components. Used reagents and processes were chosen in order to limit the environmental impact of the whole value chain. Chemical modifications were monitored by several analytical techniques such as GPC SEC for the molar mass distribution and NMR and FTIR spectrometry for the monitoring of lignin functional groups. Ink properties were characterized by rheological and colorimetric (CIE L*a*b* system) measurements on printed samples. Among the significant results, changes in hydrophilic/hydrophobic balance were particularly noticed. Furthermore, the colour gamut of modified lignin-based inks was enhanced, compared to the one of unmodified lignin-based inks. Two applications emerged from this work: (1) formulation of lignin-based bio-sourced inks, which meet most of the industrial requirements, and (2), development of a modified lignin-based coating which improved barrier properties of recycled paperboard
5
Buono, Pietro. "Chemical modification of lignin for the elaboration of novel biobased aromatic polymers and additives." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE015/document.
Повний текст джерелаАнотація:
Parmi les composants de la biomasse, la lignine est considérée comme l'un des plus prometteurs polymères naturels qui convient à la conversion de la biomasse en valable produits chimiques et matériaux. Malgré une grande quantité de lignine est générée dans l'industrie papetière, seule 2% est exploitée dans l'industrie chimique. La présence de soufre et la grande diversité moléculaire sont les principaux obstacles pour l'utilisation de la lignine. La modification chimique a été reconnue comme un outil pour contourner ces limites. Dans cette thèse, différentes stratégies de synthèse ont été appliquées pour introduire de nouveaux groupes chimiques sur une soude lignine que présents une haute fonctionnalisation de groups hydroxyles. Les dérivés correspondants de lignine ont été utilisés soit pour l’élaboration des matériaux par click polymérisations, soit pour augmenter l’hydrophobicité de la lignine à la fine de faciliter son traitement avec des matrices polymériquesAmong biomass components, lignin is considered one of the most promising natural polymers suitable for the conversion of biomass into renewable added-value chemicals and materials. However, large amount of lignin generated from wood pulping industry is burn as low cost energy source, and only 2% is exploited in the chemical industry. The presence of sulphur moieties and the large molecular diversity are the most reasons impeding the use of lignin as building blocks for the production of chemicals and materials. Chemical modifications have been acknowledged to be an important tool to circumvent these limitations. In the current work, taking advantage of the high hydroxyl groups content of a sulphur free soda lignin (SL), different synthetic strategies have been applied to introduce new chemical groups and used either to produce lignin derivatives suitable for “click” polymerization either to increase lignin hydrophobicity, facilitating its processing in polymeric matrices
6
Pouzet, Martial. "Modification de l’énergie de surface du bois par fluoration." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC086/document.
Повний текст джерелаАнотація:
La disponibilité, les aspects écologiques et économiques du bois sont autant d’avantages qui expliquent le large champ d’applications de ce matériau dans plusieurs domaines tels que la papeterie, l’ameublement, la menuiserie ou la construction. Cependant, le bois est un matériau hygroscopique très sensible aux variations d’humidité et de température ambiante. Le gonflement et le retrait causés par l’adsorption et la désorption de l’eau engendrent des fissures et des déformations dans le bois, le rendant incompatible avec certaines applications.Dans cette étude, une méthode originale a été appliquée sur des échantillons de bois (douglas et sapin) pour diminuer leur caractère hydrophile : la fluoration directe par du fluor moléculaire F2. Le greffage covalent des atomes de fluor sur la surface du bois, grâce à une substitution des groupements C-OH par des liaisons C-F, a été validé par spectroscopie infrarouge et par Résonance Magnétique Nucléaire du 19F.Le bois, qui est intrinsèquement hydrophile, acquiert un caractère hydrophobe comparable à celui du Téflon grâce à la fluoration. Des études de vieillissements sous atmosphère ambiante et irradiation UV ont permis de déterminer une bonne durabilité du traitement. De plus, ce traitement permet d’obtenir un caractère hydrophobe sans changements structuraux (morphologie, densité et couleur) ou mécaniques majeurs. Grâce au caractère surfacique de la fluoration, la conservation de ces propriétés après la fluoration s’avère être un remarquable avantage par rapport aux autres traitements physiques et chimiques classiquement utilisés dans l’industrie du boisThe availability, the ecological and economic characteristics of wood are advantages which explain the very wide scope of applications of this material in several domains such as the paper industry, furniture, carpentry and construction. However, wood is a hygroscopic material, highly sensitive to ambient humidity and temperature. The swelling and the shrinking caused by water adsorption and desorption cycles lead to cracking and deformation in the wood volume, making it incompatible for some applications.In this study an original surface treatment was applied to wood samples (douglas and silver fir species) to decrease their hydrophilic character: direct fluorination using F2 gas. The covalent grafting of fluorine atoms onto extreme wood surfaces through a conversion of C-OH groups into C-F was evidenced by Fourier-Transform infrared spectroscopy and 19F solid state Nuclear Magnetic Resonance.The wood which is initially hydrophilic acquires a hydrophobic character comparable to that of Teflon, thanks to fluorination. Good durability of this treatment under ambient atmosphere and UV irradiation was also highlighted. Moreover, because it affects only the extreme surface, this treatment allowed us to obtain a hydrophobic character without major structural (morphology, density and colour) or mechanical changes. The maintaining of these properties after fluorination appears to be a remarkable advantage over other traditional physical and chemical wood treatments
7
Bin, Hussin Mohd Hazwan. "Extraction, modification and characterization of lignin from oil palm fronds as corrosion inhibitors for mild steel in acidic solution." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0135/document.
Повний текст джерелаАнотація:
La biomasse lignocellulosique en Malaisie peut être considérée comme l'une des sources d'énergie renouvelable prometteuse. Elle est principalement composée de cellulose, d'hémicellulose et de lignine et est adaptée pour des applications dans les domaines de l'énergie et de la chimie en raison de sa disponibilité suffisante, de son faible coût et de son caractère renouvelable. La production de biomasse lignocellulosique en Malaisie est considérée comme élevée et est issue en grande partie de l'industrie de l'huile de palme (environ 60 millions de tonnes de déchets d'huile de palme sont générés en un an). Les déchets de l’industrie de l'huile de palme pourraient être utilisés comme ressources alternatives pour la production de papier et de carton. Cependant, dans ce contexte, d'énormes quantités de lignine seraient rejetées (par l'industrie des pâtes et papier) en raison du manque de prise de conscience de son potentiel. Avec une teneur élevée en groupes fonctionnels divers (-OH phénoliques et aliphatiques, les carbonyles, les carboxyles, etc.), la lignine pourrait être utilisée en substitution de produits actuels dans des applications industrielles telles que l'inhibition de la corrosion des métaux et alliages. Les frondes de palmier à huile (OPF) étant l'un des plus gros contributeurs de déchets de biomasse en Malaisie, elles ont donc été utilisées comme matière première dans cette étude. Afin d'améliorer l'extractabilité de la lignine et ses propriétés, l'extraction a été effectuée de différentes façons (par délignification directe et / ou des méthodes de pré-traitement combiné). Cependant, la forte hydrophobicité de la lignine limite sa capacité à agir comme inhibiteur de corrosion efficace. Par conséquent, des modifications de la structure de la lignine OPF ont été effectuées de deux manières ; (1) en incorporant des piégeurs de recondensation de la lignine (2-naphtol et 1,8-dihydroxyanthraquinone) pendant le prétraitement par autohydrolyse avant le traitement organosolv (pourcentage de rendement de la lignine: AHN EOL = 13,42 ± 0,71% et AHD EOL = 9,64 ± 0,84%) et (2) le fractionnement de la lignine à partir de procédés de délignification directs (Kraft, à la soude et organosolv) par l'intermédiaire d'une technique d'ultrafiltration à membrane (rendement en pourcentage de fractions de lignine perméat: Kraft = 5,41 ± 2,04%; soude = 12,29 ± 0,54% et organosolv = 1,48 ± 0,15%). Les propriétés physiques et chimiques des lignines modifiées ont été évaluées en utilisant l'infrarouge à transformée de Fourier (FTIR), la résonance magnétique nucléaire (RMN), chromatographie par perméation de gel (GPC), l'analyse thermique et la Chromatographie liquide à haute performance (HPLC). Des fractions de lignine modifiée présentant des teneurs en OH phénoliques élevées, des poids moléculaires, polydispersité et contenus en OH aliphatiques faibles ont abouti à des valeurs plus élevées de l'activité antioxydante. L'activité antioxydante semble être dépendante de la teneur en OH phénolique et en ortho-méthoxyle, grâce à la stabilité du radical formé et la capacité de réduire les ions Fe3+ en Fe2+ ions. En effet, les propriétés physico-chimiques améliorées et une activité anti-oxydante de lignine modifiée a donné une corrélation positive avec l'inhibition de la corrosion de l'acier doux dans l'action solution de HCl 0,5 M qui a été évaluée par spectroscopie d'impédance électrochimique (SIE), de polarisation et de la perte de poids mesure potentiodynamique. La meilleure efficacité de pourcentage d'inhibition (ex: 81 à 90%) a été obtenu à la concentration de 500 ppm pour les inhibiteurs de la lignine, mais a diminué avec l'augmentation de la température (303 à 333 K). Les données thermodynamiques indiquent que l'adsorption de la lignine modifiée sur l'acier doux a été spontanée et que les inhibiteurs ont été principalement adsorbés physiquement (physisorption), ce résultat étant confirmé par l'énergie d'activation de l'adsorption, Ea. [...]Lignocellulosic biomass in Malaysia can be considered as one of the promising sources of renewable energy. It is mainly composed of cellulose, hemicellulose, and lignin and best-suited for energy and chemical applications due to its sufficient availability, inexpensive and is sustainable. In general, the production of lignocellulosic biomass in Malaysia was considered high and mainly derived from the palm oil industries (approximately 60 million tonnes of oil palm waste were generated in a year). The oil palm biomass waste could possibly be used as alternative resources for the production of paper and cardboard. However, massive amounts of lignin by-product could also be discarded in huge quantities (by the pulp and paper industry) due to lack of awareness on its potential. Having high content of diverse functional groups (phenolic and aliphatic –OH, carbonyls, carboxyls, etc.) and phenylpropanoid structure, lignin can lead to substitutes in industrial applications such as in corrosion inhibition of metals and alloys. Since the oil palm fronds (OPF) are one of the largest biomass waste contributors in Malaysia, it was therefore used as raw material in this study. In order to improve the lignin extractability and properties, the extraction was conducted in different ways (via direct delignification and/or combined pretreatment methods). Due to the high hydrophobicity of lignin, it limits the capability to act as efficient corrosion inhibitors. Hence, modifications of the OPF lignin structure were conducted in two ways; (1) by incorporating organic scavengers (2-naphthol and 1,8-dihydroxyanthraquinone) during autohydrolysis pretreatment before organosolv treatment (percentage yield of lignin: AHN EOL = 13.42±0.71 % and AHD EOL = 9.64±0.84 %) and (2) fractionation of lignin from direct delignification processes (Kraft, soda and organosolv) via ultrafiltration membrane technique (percentage yield of permeate lignin fractions: Kraft = 5.41±2.04 %; soda = 12.29±0.54 % and organosolv = 1.48±0.15 %). The physical and chemical properties of the modified lignins were evaluated by using Fourier Transform Infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), thermal analysis and high performance liquid chromatography (HPLC). Modified lignin fractions with higher phenolic –OH content but lower molecular weight, polydispersity as well as aliphatic –OH content resulted in higher values of antioxidant activities. The antioxidant activity seems be dependent on the increase of their free phenolic –OH and ortho-methoxyl content, through the stability of the radical formed and the ability to reduce Fe3+ ions to Fe2+ ions. Indeed, the improved physicochemical properties and antioxidant activity of modified lignin gave positive correlation with the mild steel corrosion inhibition action in 0.5 M HCl solution that were evaluated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss measurements. The best percentage of inhibition efficiencies (IE: 81 – 90 %) were attained at the concentration of 500 ppm for all lignin inhibitors but decreased with the increase in temperature (303 – 333 K). Thermodynamic data indicated that the adsorption of the modified lignin onto the mild steel was spontaneous and the inhibitors were mainly physically adsorbed (physiosorption), supported by the activation energy of adsorption, Ea. The enhanced protective properties of the modified lignin will pave way for an alternative approach for the utilization of these natural waste materials
8
MARTZ, FRANCOISE. "Modification de l'activite o-methyltransferase dans des tabacs transgeniques : consequences sur la lignine et la resistance au virus de la mosaique du tabac." Université Louis Pasteur (Strasbourg) (1971-2008), 1997. http://www.theses.fr/1997STR13132.
Повний текст джерелаАнотація:
Chez les plantes, le metabolisme des phenylpropanoides conduit a de nombreux composes aromatiques dont la lignine. Ce metabolisme est induit lors des reactions de defense face a des agents pathogenes, notamment lors de la reaction hypersensible du tabac au virus de la mosaique du tabac. La lignine derive de la polymerisation de trois monomeres se distinguant par leur nombre de groupements methoxyles (0, 1 ou 2), introduits lors de deux etapes de methylation catalysees par des o-methyltransferases. Chez le tabac, deux classes de comt existent : la classe i impliquee dans la lignification, et la classe ii specifique des reactions de defense. Les memes enzymes catalysent les deux etapes de methylation in vitro. Dans le but de modifier la lignine et d'etudier le role des phenylpropanoides dans le defense, nous avons modifie les activites comt i ou ii dans des tabacs transgeniques. Differents fragments d'adnc de chaque classe de comt ont ete integres dans des tabacs en orientation sens ou antisens. Des lignees stables modifiees pour leur activite comt i ou ii ont ete isolees. Des inhibitions d'activite superieures a 90% ont ete obtenues par effet antisens ou par cosuppression avec la classe i. Ces inhibitions, stables pendant la croissance, provoquent la disparition des unites dimethoxylees de la lignine alors que la teneur en unite monomethoxylee augmente, indiquant qu'un autre enzyme catalyse la premiere methylation in vivo. Des resultats preliminaires obtenus avec les transformants ayant une activite comt ii diminuee montrent une diminution significative de la resistance au vmt compare aux plantes temoins, confirmant le role des phenylpropanoides dans la defense. La cafeoylcoa-omt, intervenant dans la premiere etape de methylation, a ete caracterisee chez le tabac : 4 adnc correspondants ont ete clones et le profil d'expression des genes de ccoaomt apparait semblable a celui des genes de comt i, ce qui est en accord avec le role des deux omt dans la lignification.
9
Khadraoui, Malek. "Valorisation des déchets de posidonie pour l'obtention de matériaux biosourcés à forte valeur ajoutée." Thesis, Université Grenoble Alpes, 2022. http://www.theses.fr/2022GRALI052.
Повний текст джерелаАнотація:
Le projet de thèse a visé la valorisation des déchets de Posidonia oceanica par la production de nanomatériaux biosourcés à haute valeur ajoutée. Dans ce contexte, l'accent a été mis sur les micro/nanofibrilles de cellulose (M/NFC) qui sont prometteuses, en raison de leurs bonnes propriétés mécaniques, optiques et rhéologiques. L’inconvenient majeur de la production de M/NFC est la consommation energétique elevée des procédés mécaniques de fibrillation et de microfibrillation.Ainsi, l'objectif de ce travail est la production de micro/nanofibrilles de cellulose avec un impact environnemental réduit. Tout d'abord, l'utilisation de l'explosion à la vapeur, un procédé écologique, pour l'étape de microfibrillation a été étudiée, combinée (ou non) avec l'oxydation médiée par TEMPO comme prétraitement chimique. Cette voie proposée a été comparée au broyage conventionnel pour la production de micro/nanofibrilles de cellulose blanchies de haute qualité. Ensuite, l'étape de blanchiment et les prétraitements chimiques ont été éliminés de la voie de production de M/NFC. Au cours de cette deuxième stratégie, l'utilisation de l'explosion à la vapeur et de l'extrusion à double vis pour la fibrillation a été élucidée (processus alternatif de raffinage) pour produire des micro/nanofibrilles de cellulose contenant de la lignine (LM/NFC). Enfin, pour améliorer la qualité des M/NFC produites (en raison du caractère hydrophobe de la lignine), l'application de la sulfonation de la lignine a été étudiée (explosion à la vapeur in situ et comme prétraitement chimique doux après explosion à la vapeur). Par rapport aux méthodes conventionnelles de production de M/NFC, le blanchiment et les prétraitements chimiques ou enzymatiques ont pu être éliminés. Par conséquent, on a assumé que la qualité du produit est différente, fournissant différentes propriétés permettant leur utilisation dans divers domaines. Cette stratégie a permis de produire un matériau économique et écologique tout en tenant compte du rendement élevé des procédés, de l’utilisation limitée des produits chimiques et de la faible consommation énergétique lors de la production des LM/NFCThe PhD project was dedicated to the Posidonia oceanica waste valorisation by the production of bio-based nanomaterials with high added value. In this context, the focus was oriented toward cellulose micro/nanofibrils (CM/NF) which are promising, due to their good mechanical, optical, and rheological properties. The bottleneck of CM/NF production is its high energy consumption during the mechanical fibrillation and microfibrillation processes.The purpose of this work is the production of cellulose micro/nanofibrils with a reduced environmental impact. First, the use of steam explosion, as an ecofriendly process, for microfibillation step was studied combined (or not) with TEMPO-mediated oxidation as chemical pretreatment and was compared to conventional grinding for the production of a bleached high-quality cellulose micro/nanofibrils. Then bleaching step and chemical pretreatments were eliminated in the CM/NF pathway production. During this second strategy the use of steam explosion and twin-screw extrusion for fibrillation was elucidated (processes for alternative refining) to produce lignin-containing cellulose micro/nanofibrils (LCM/NF). Finally, to improve the quality of the produced LCM/NF (due to the hydrophobic character of lignin), the application of lignin sulfonation was investigated (in situ steam explosion and as soft chemical pretreatment after the steam explosion). Compared to the conventional methods of CM/NF production, bleaching and chemical or enzymatic pretreatments could be successfully eliminated. Therefore, it is assumed that the quality of the product is different, providing different properties allowing their use in various fields. This strategy enabled the production of economical and ecological materials taking into account the high yield, low use of chemicals and low mechanical energy consumption during LCNM/F production
10
Khandal, Dhriti. "Traitement sous rayonnement ionisant de mélanges amidon-lignine et de leurs modèles : étude et quantification des modifications induites." Thesis, Reims, 2012. http://www.theses.fr/2012REIMS021/document.
Повний текст джерелаАнотація:
Cette travail été réalisée dans le cadre de la Projet LignoStarch ANR CP2D pour connaître les différents phénomènes induite par rayonnement ionisants dans les mélanges de l'amidon et lignine au niveau moléculaire. L'amidon peut être utilisé seul ou en combinaison avec d'autres composés pour élaborer des articles biodégradables à partir de ressources renouvelables. La lignine et ses dérivés sont bons candidats pour limiter la sensibilité d'eau des matériaux à base d'amidon, mais ils ne sont pas compatibles avec des polysaccharides. Le traitement sous faisceau d'électrons est proposé comme une méthode efficace pour induire les liaisons covalentes entre les deux constituants (amidon et lignine). En comparaison avec les mélanges de départ, les propriétés des mélanges irradiés montrent qu'il est possible d'ajuster les propriétés mécaniques du matériau final. Afin d'améliorer la compréhension et la maîtrise de ces effets de l'irradiation, une étude de mélanges modèles de maltodextrines et de divers alcools ou acides aromatiques a été réalisée. Les résultats montrent une compétition entre les phénomènes de dégradation par scission et le greffage. Les analyses par CES, RMN, et MALDI-TOF permettent de mettre en évidence et de quantifier les greffages consécutifs à l'irradiation. L'exploitation par la méthode statistique proposée par Saito des données relatives à l'évolution des masses molaires et des fractions de gel dans des mélanges à base de pullulane permet d'accéder à des grandeurs quantifiant l'efficacité des deux réactions en compétition. Ainsi, les rendements radiochimiques de coupure de chaine G(S) et de pontage G(X) ont pu être calculés pour différentes quantités d'alcool cinnamique introduites dans les mélanges. Les évolutions observées rendent bien compte de la formation de gel qui n'est observée qu'en présence d'une quantité minimale d'alcool aromatique, lorsque la condition G(s) < 4 G(x) est satisfaite. Mots Clés : Amidon, Lignine, Maltodextrine, Maltotriose, Pullulane, Composés Modèles de la Lignine (Additif Aromatiques), Scission, Réticulation, Greffage, Faisceau d'Electrons, Rendements Radiochimiques de Scission G(s) et Réticulation G(x), Méthode Saito, Méthode Charlesby-PinnerThis work was part of the LignoStarch ANR CP2D Project aimed at understanding the radiation-induced processes and mechanisms in thermoplastic starch – lignin mixture at the molecular level. Starch has the advantage of being biodegradable and agriculture based renewable resource that can be converted into a thermoplastic material with or without any additive. Lignin and its derivatives are good candidates for reducing the water sensitivity of starch based materials; however being hydrophobic in nature they are not compatible with the polysaccharides. Electron Beam radiation has been proposed as an efficient method for modifying the starch lignin blends and creating covalent linkages between the two constituents for improved blend stability. Previous studies as part of the Project have shown that the mechanical properties of the irradiated blends can be positively modified by choosing an appropriate blend composition. For a better understanding of how the properties of the blend can be tailored, an understanding of the radiation-induced processes was carried out using model blends comprising maltodextrin and different aromatic compounds having structural features of lignin monomers. The blends were analyzed using SEC, NMR, and MALDI-TOF for placing in evidence the phenomenon of radiation-induced grafting to compete with chain scission in presence of the aromatic additives. The quantification of the radiochemical yields of scission G(s) and crosslinking G(x) were carried out using the blends of pullulan polysaccharide as a function of varying amounts of aromatic additive in the blend. The methods of calculation exploited here are based on the study of radiation-induced molecular mass changes before the formation of gel as proposed by Saito and the quantification of sol-gel content for formulations resulting in gel as proposed by the Charlesby-Pinner method. The condition of gel formation G(s) < 4 G(x) is found to be valid for a certain minimum quantity of aromatic additive for high applied doses.Keywords: Starch, Lignin, Maltodextrin, Pullulan, Lignin-like Monomers (Aromatic Additives), Scission, Crosslinking, Grafting, Electron Beam, Radiochemical yields of Scission G(s) and Crosslinking G(x), Saito Method, Charlesby-Pinner Method
Книги з теми "Modification de lignine"
1
Hu, Thomas Q., ed. Chemical Modification, Properties, and Usage of Lignin. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0643-0.
Повний текст джерела
2
Service, Alberta Forest, Canadian Forestry Service, Canada-Alberta Forest Resource Development Agreement., and Alberta Research Council. Biotechnology Dept., eds. Biotechnological modification of lignin. [Ottawa, Ont: Forestry Canada, 1989.
Знайти повний текст джерела
3
Q, Hu Thomas, ed. Chemical modification, properties, and usage of lignin. New York: Kluwer Academic/Plenum Publishers, 2002.
Знайти повний текст джерела
4
Hu, Thomas Q. "Chemical Modification, Properties, and Usage of Lignin". Springer, 2013.
Знайти повний текст джерела
5
Hu, Thomas Q. Chemical Modification, Properties, and Usage of Lignin. Springer, 2002.
Знайти повний текст джерела
6
Allen, Stephen Glen. Organosolv lignin characterization, modification and application in phenol-formaldehyde adhesives. 1993.
Знайти повний текст джерела
7
Huang, Caoxing, Chunlin Xu, Xianzhi Meng, Lei Wang, and Xin Zhou, eds. Isolation, Modification, and Characterization of the Constituents (Cellulose, Hemicellulose, Lignin, et al.) in Biomass and Their Bio-based Applications. Frontiers Media SA, 2022. http://dx.doi.org/10.3389/978-2-88976-277-4.
Повний текст джерелаЧастини книг з теми "Modification de lignine"
1
Lopez-Camas, Karen, Muhammad Arshad, and Aman Ullah. "Chemical Modification of Lignin by Polymerization and Depolymerization." In Lignin, 139–80. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40663-9_5.
Повний текст джерела
2
Toriz, G., F. Denes, and R. A. Young. "Plasma Modification of Lignin." In ACS Symposium Series, 367–89. Washington, DC: American Chemical Society, 1999. http://dx.doi.org/10.1021/bk-2000-0742.ch019.
Повний текст джерела
3
Baumberger, Stéphanie. "Starch-Lignin Films." In Chemical Modification, Properties, and Usage of Lignin, 1–19. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0643-0_1.
Повний текст джерела
4
Hatakeyama, Hyoe. "Polyurethanes Containing Lignin." In Chemical Modification, Properties, and Usage of Lignin, 41–56. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0643-0_3.
Повний текст джерела
5
Kadla, John F., Satoshi Kubo, Richard D. Gilbert, and Richard A. Venditti. "Lignin-Based Carbon Fibers." In Chemical Modification, Properties, and Usage of Lignin, 121–37. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0643-0_7.
Повний текст джерела
6
Struszczyk, Henryk. "New Trends in Modification of Lignins." In ACS Symposium Series, 245–61. Washington, DC: American Chemical Society, 1989. http://dx.doi.org/10.1021/bk-1989-0397.ch018.
Повний текст джерела
7
Paulsson, Magnus, and Rune Simonson. "Acetylation of Lignin and Photostabilization of Lignin-Rich Mechanical Wood Pulp and Paper." In Chemical Modification, Properties, and Usage of Lignin, 221–45. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0643-0_12.
Повний текст джерела
8
Fischer, Klaus, and Rainer Schiene. "Nitrogenous Fertilizers from Lignins — A Review." In Chemical Modification, Properties, and Usage of Lignin, 167–98. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0643-0_10.
Повний текст джерела
9
Paulsson, Magnus, and Arthur J. Ragauskas. "Chemical Modification of Lignin-Rich Paper." In ACS Symposium Series, 490–504. Washington, DC: American Chemical Society, 1999. http://dx.doi.org/10.1021/bk-2000-0742.ch025.
Повний текст джерела
10
Feldman, Dorel. "Lignin and Its Polyblends — A Review." In Chemical Modification, Properties, and Usage of Lignin, 81–99. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0643-0_5.
Повний текст джерелаТези доповідей конференцій з теми "Modification de lignine"
1
Panamgama, L. A., and P. R. U. S. K. Peramune. "Extraction and modification of lignin biopolymer." In 2017 Moratuwa Engineering Research Conference (MERCon). IEEE, 2017. http://dx.doi.org/10.1109/mercon.2017.7980448.
Повний текст джерела
2
Osbert, Ashaba, Samson Rwahwire, and Yvonne Tusiimire. "Re-Engineering Plastic Waste for the Modification of Bitumen Blends." In International Conference on Advances in Materials Science 2021. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/p-31t6r8.
Повний текст джерелаАнотація:
The increase in the production and utilization of plastics has created a never-ending problem of plastic waste. Developing countries face challenges with plastic waste disposal that in due process negatively impacts the environmental ecosystem. That notwithstanding, it suffices to mention that most developing countries have poor road networks that pose a burden towards smooth economic and social development. The problem is further exacerbated by the limited availability of bitumen which is usually imported but also has environmental concerns. It is against this background that we proposed alternative binders from plastic waste which can help developing countries to manage plastic waste as well as build road networks, thereby leading to sustainable development. We explored the 80/100 penetration grade bitumen modification (Penetration grade 85 and Softening temperature 46°C) using polyethylene terephthalate (PET) waste (2 – 12%) and lignin (0.2%) as a crosslinking agent by weight for every PET waste – Bitumen sample. The research showed that Plastic waste and lignin improved the performance of bitumen. The modified bitumen with 10% waste PET and 0.2% lignin enhanced the softening point and penetration points to 55°C and 46, respectively; hence the incorporation of PET and lignin provided better properties compared to the neat bitumen.
3
Kakaras, Emmanuel, Panagiotis Grammelis, George Skodras, and Panagiotis Vourliotis. "Experience on Combustion and Co-Combustion of Greek Brown Coal in Fluidized Bed Facilities." In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-128.
Повний текст джерелаАнотація:
The paper aims to present the experience gained from the combustion trials of Greek brown coal in different installations, both in semi-industrial and laboratory scale. Specifically, these research activities are separated in two parts, i.e. combustion tests using only brown coal and co-combustion tests with brown coal and biomass. Combustion tests with Greek lignite were realised in three different Circulating Fluidized Bed Combustion (CFBC) facilities. Low rank lignite was burned in a pilot scale facility of approx. 100kW thermal capacity, located in Athens (NTUA) and a semi-industrial scale of 1.2 MW thermal capacity, located at RWE’s power station Niederaussem in Germany. The results include the determination of operating conditions to achieve proper fuel burnout, the examination of the influence of air staging on the temperature distribution inside the reactor and the investigation of the combustion behaviour of the particular fuel type and emitted pollutants. Several conclusions are drawn concerning the necessary modifications and requirements of the plant layout when a large scale CFBC installation is designed to utilize low grade brown coal. Co-combustion tests with Greek xylitic lignite and waste wood were carried out in the 1 MWth CFBC installation of AE&E, in Austria. During the tests, oxygen concentration and CO, SO2, N2O and NOX emissions were continuously monitored. Ash samples were collected and analysed for heavy metals content in ICP-AES spectrophotometer. The improved combustion behaviour of this lignite type was more than evident, since it has lower moisture content and increased calorific value. In all co-combustion tests, low emissions of gaseous pollutants were obtained and metal element emissions were lower than the corresponding values anticipated by the guidelines. In addition, lab-scale co-combustion tests of Greek pre-dried lignite with biomass were accomplished in a bubbling fluidised bed. The main purpose of these experiments was to examine ash melting problems and differentiation to the emitted pollutants due to biomass addition. The obtained results of all aforementioned activities showed that fluidised bed is the appropriate combustion technology to efficiently exploit the low quality Greek brown coal either alone or in conjunction with other biomass materials.
4
Nelson, Matt, Pannalal Vimalchand, WanWang Peng, Tim Lieuwen, Diane Revay Madden, Paul Miller, Tim Pinkston, and Steve Wilson. "Syngas Production and Combustion Turbine Operation With Hydrogen-Rich Fuel at the Kemper County IGCC." In ASME 2018 Power Conference collocated with the ASME 2018 12th International Conference on Energy Sustainability and the ASME 2018 Nuclear Forum. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/power2018-7173.
Повний текст джерелаАнотація:
The Kemper County Project has demonstrated Transport Integrated Gasification (TRIG™) at a 2-on-1 Integrated Gasification Combined-Cycle (IGCC) facility located in Kemper County, Mississippi. Kemper is the largest IGCC project in the world, the first to use lignite as fuel, the first to capture and sell CO2, and the first to produce multiple byproducts from initial startup. The facility features two Siemens SGT6-5000F gas turbines, each capable of operating on a high-hydrogen syngas produced in the Transport Gasifiers from locally mined lignite. Using high-hydrogen syngas requires unique modifications to the combustion turbine design. Flame-diffusion combustors, rather than dry low-NOX designs, prevent flashback caused by the high hydrogen content of the syngas. Also, ports added to the turbine compressor casing allow air to be extracted from the compressor and used elsewhere in the plant, supplying up to one half of the air required by the gasifier. The Kemper facility has achieved the integrated operation of both gasifiers, including the production of electricity from syngas by both combustion turbines. Turbine operation on the high hydrogen syngas was smooth both during normal operations and during transitions, with efficiencies meeting or exceeding expectations. This paper describes the Kemper plant design, focusing on the combustion turbine design unique to Kemper. The paper also discusses turbine design challenges specific to Kemper, provides an overview of the robust control scheme used on both syngas and natural gas co-firing operations, and provides preliminary operational and performance results, including inspection findings.
5
Le Guevel, Thierry, and Philippe Thomas. "Fuel Flexibility and Petroleum Coke Combustion at Provence 250 MW CFB." In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-094.
Повний текст джерелаАнотація:
The Provence 250 MWe CFB boiler was originally designed in 1992 for a local coal (Provence lignite) with a high sulfur and high ash content. This large CFB, features a pant leg bottom furnace, 4 cyclones and 4 fluid bed heat exchangers to provide the active temperature control of the furnace and reheated steam final temperature. After start up in 1995 with this local coal, several other fuel types were burnt. Mainly 3 fuels were tested over the last 5 years, on a long term basis, with various degrees of combination with the Gardanne coal up to full firing alone: • a lean coal (Gard, France), low volatile bituminous type, not far from semi anthracite type coals, • an imported coal, representative of low ash low sulfur content imported coal, • a petroleum coke, with a high sulfur content. This last test demonstrates the widest flexibility with regards to fuel reactivity range of a CFB plant with this architecture. The fuel, limestone and ash handling/injection systems were able to cope with this fuel diversity without equipment modifications. Since these tests were conclusive both on the pollutant emissions and on the operating concern, a permit to burn petroleum coke in commercial operation in a 250 MWe CFB boiler has been obtained in December 2001. This paper presents the main features and the results of the petroleum coke tests performed and compare them with the feedback on operating conditions of the boiler and emissions performances for Provence lignite and imported coal. These positive results demonstrate the wide fuel capability of large CFB boilers with this boiler architecture. First, they emphasize the critical role of advanced cyclones to accept fuels with very different reactivities and minimize limestone consumption. Second, these results show the role of the Fluid Bed Heat Exchangers system to control actively the furnace temperature, while controlling the reheated steam temperature without using spray.
6
Hossain, Mohammad K., Mohammad R. Karim, Mahmudur R. Chowdhury, Muhammad A. Imam, Mahesh Hosur, Shaik Jeelani, and Ramsis Farag. "Tensile Properties Evaluation of Chemically Treated/Untreated Single Sugarcane Fiber." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65664.
Повний текст джерелаАнотація:
Natural fiber as a reinforcing constituent can play a dominant role in the field of fiber reinforced polymer composites (FRPC) due to its eco-friendliness, renewability, abundance in nature, co2-neutrality, flexibility, low density, and low cost. Hence, sugarcane fiber can be a potential candidate to replace the synthetic FRPC. The objective of this study is to evaluate the effect of chemical treatment on the tensile properties of single sugarcane fiber. Sugarcane collected from the local market was cut into some specific length and fibers were extracted from the juicy section. These fibers were then dried in an oven to remove the moisture. Surface modification was accomplished by performing alkali treatment and neutralizing by acetic acid solution. The fiber was then rinsed with water and dried at 80°C for about twenty four hours using an oven. Untreated and treated fibers were characterized using tensile testing according to the ASTM D 3822-01 standard. Optical microscopy (OM) was employed to measure the diameter of the fiber and scanning electron microscopy (SEM) was used to evaluate the fracture morphology of failed samples. Tensile tests were carried out on the span length of 25 mm of the single fiber. The resultant data showed that maximum improvement in the tensile strength and modulus was observed to be 87% and 29%, respectively, compared to those of untreated ones due to chemical treatments using 5% NaOH solution and 2% acetic acid solution, respectively. Strain to maximum strength was enhanced by about 16% compared to that of the untreated one. A small initial weight loss was observed in the temperature ranging from 25 to 150 °C due to the evaporation of water. However, untreated fiber started to decompose at around 200 °C while treated fiber started to become decomposed at around 250°C. It might be due to the removal of non-cellulosic substances including hemicellulose, lignin, and pectin as a result of the chemical treatment. Fracture morphology of the treated fiber revealed rougher fracture surfaces compared to untreated fiber surfaces. This is an indication of more energy absorption by the treated fibers during the tensile loading.
7
Green, Alex E. S., M. S. Sankar, and P. Venkatachalam. "Feedstock Blending of Domestic Fuels in Gasifier/Liquifiers." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30009.
Повний текст джерелаАнотація:
In early studies addressing national energy/environmental (EE) problems we concluded that co-utilization of domestic fuels can significantly reduce national reliance on imported fuels, mitigate NOx, SOx, CO2 and other undesirable emissions and provide valuable waste disposal services. Co-firing of coal and biomass for steam turbine power generation is a near-term co-utilization approach that can make use of existing facilities with relatively minor modifications. However, co-gasification by providing fuel for more efficient combustion turbines and fuel cells and co-liquification to produce transportation fuels have greater long-term EE potential. The development of optimum thermo-chemical co-conversion systems can be fostered by developing a common systematics for the pyrolysis of biomass and coal. Towards this goal we have used the large data bases from ASTM standard ultimate and proximate analyses for all fuels along natures coalification path from biomass to peat, lignite, bituminous and anthracite coal. With this composite data we find systematics in the weight percentages of carbon, hydrogen, total volatiles, fixed carbon and feedstock HHVs vs the weight percentage of oxygen. To meet the need for knowledge of the volatile constituents we have used sparsely available slow pyrolysis data in the literature and our own data to further develop a plausible semi-empirical model (SEM) that relates feedstock and product compositions. We here extend these analytic correlations to lower temperatures with the help of CCTL measurements of yields from the pyrolysis of rice hulls. We have recently applied this SEM to exam the systematic yields of a short list (SL) of products (five gases and five liquids) vs [O], the weight percentage of oxygen in the feedstock. Here anchored to the rice hull data we use our analytical relationships to estimate the yields of a long list (LL) of products including many organic compounds that are known to be slow pyrolysis products of coals and biomass. These relations are put forth as a heuristic challenge to ourselves and to specialists in biomass and coal pyrolysis to obtain more and better data and to seek improved engineering formulas that are needed to advanced co-utilization technology. Then energy debtor nations could utilize all of their available domestic fuels, including opportunity fuels, to mitigate their national EE problems. These preliminary results point to a path towards the development of a co-utilization science and technology for optimizing feedstock blends in many co-firing, co-gasifying or co-liquifying applications.
Звіти організацій з теми "Modification de lignine"
1
Tien, Ming. Modification of Lignin by Protein Cross-linking to Facilitate Production of Biofuels From Poplar. Office of Scientific and Technical Information (OSTI), April 2013. http://dx.doi.org/10.2172/1129008.
Повний текст джерела