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Literatura académica sobre el tema "Derivati cellulosa"

Autor: Grafiati

Publicado: 10 de marzo de 2023

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Artículos de revistas sobre el tema "Derivati cellulosa"

Demirdogen, Ruken Esra, Tuncay Yeşilkaynak, Tetyana Tishakova y Fatih Mehmet Emen. "Antibacterial Cellulose Acetate Microfibers Containing Pyridine Derivative Complexes". Chemistry & Chemical Technology 15, n.º 2 (15 de mayo de 2021): 217–25. http://dx.doi.org/10.23939/chcht15.02.217.

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Pyridine (L1) and 2,4-dimethylpyridine (L2) halide complexes of the type of [ML2X2] were prepared and characterized via FT-IR and 1H NMR. The CA microfibers containing complexes were electrospun and investigated via FT-IR. The morphologies of the microfibers were investigated via FE-SEM. Antibacterial activities of the complexes and the fibers were investigated.

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Kawamura, Kaito, Takatsugu Abera y Hiroshi Nonaka. "Extrusion Molding of Cellulosic Fibers Using Cellulose Derivative". JAPAN TAPPI JOURNAL 72, n.º 3 (2018): 321–27. http://dx.doi.org/10.2524/jtappij.72.321.

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Shaikh, Hamid M., Arfat Anis, Anesh Manjaly Poulose, Saeed M. Al-Zahrani, Niyaz Ahamad Madhar, Abdullah Alhamidi, Saleh Husam Aldeligan y Faisal S. Alsubaie. "Synthesis and Characterization of Cellulose Triacetate Obtained from Date Palm (Phoenix dactylifera L.) Trunk Mesh-Derived Cellulose". Molecules 27, n.º 4 (21 de febrero de 2022): 1434. http://dx.doi.org/10.3390/molecules27041434.

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Cellulosic polysaccharides have increasingly been recognized as a viable substitute for the depleting petro-based feedstock due to numerous modification options for obtaining a plethora of bio-based materials. In this study, cellulose triacetate was synthesized from pure cellulose obtained from the waste lignocellulosic part of date palm (Phoenix dactylifera L.). To achieve a degree of substitution (DS) of the hydroxyl group of 2.9, a heterogeneous acetylation reaction was carried out with acetic anhydride as an acetyl donor. The obtained cellulose ester was compared with a commercially available derivative and characterized using various analytical methods. This cellulose triacetate contains approximately 43.9% acetyl and has a molecular weight of 205,102 g·mol−1. The maximum thermal decomposition temperature of acetate was found to be 380 °C, similar to that of a reference sample. Thus, the synthesized ester derivate can be suitable for fabricating biodegradable and “all cellulose” biocomposite systems.

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Correia, Daniela M., Erlantz Lizundia, Rafaela M. Meira, Mikel Rincón-Iglesias y Senentxu Lanceros-Méndez. "Cellulose Nanocrystal and Water-Soluble Cellulose Derivative Based Electromechanical Bending Actuators". Materials 13, n.º 10 (15 de mayo de 2020): 2294. http://dx.doi.org/10.3390/ma13102294.

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This study reports a versatile method for the development of cellulose nanocrystals (CNCs) and water-soluble cellulose derivatives (methyl cellulose (MC), hydroxypropyl cellulose (HPC), and sodium carboxymethyl cellulose (NaCMC)) films comprising the ionic liquid (IL) 2-hydroxy-ethyl-trimethylammonium dihydrogen phosphate ([Ch][DHP]) for actuator fabrication. The influence of the IL content on the morphology and physico–chemical properties of free-standing composite films was evaluated. Independently of the cellulose derivative, the ductility of the films increases upon [Ch][DHP] incorporation to yield elongation at break values of nearly 15%. An increase on the electrical conductivity as a result of the IL incorporation into cellulosic matrices is found. The actuator performance of composites was evaluated, NaCMC/[Ch][DHP] showing the maximum displacement along the x-axis of 9 mm at 8 Vpp. Based on the obtained high electromechanical actuation performance, together with their simple processability and renewable nature, the materials fabricated here represent a step forward in the development of sustainable soft actuators of high practical relevance.

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Nechifor, Aurelia Cristina, Andreia Pîrțac, Paul Constantin Albu, Alexandra Raluca Grosu, Florina Dumitru, Ioana Alina Dimulescu (Nica), Ovidiu Oprea, Dumitru Pașcu, Gheorghe Nechifor y Simona Gabriela Bungău. "Recuperative Amino Acids Separation through Cellulose Derivative Membranes with Microporous Polypropylene Fiber Matrix". Membranes 11, n.º 6 (5 de junio de 2021): 429. http://dx.doi.org/10.3390/membranes11060429.

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The separation, concentration and transport of the amino acids through membranes have been continuously developed due to the multitude of interest amino acids of interest and the sources from which they must be recovered. At the same time, the types of membranes used in the sepa-ration of the amino acids are the most diverse: liquids, ion exchangers, inorganic, polymeric or composites. This paper addresses the recuperative separation of three amino acids (alanine, phe-nylalanine, and methionine) using membranes from cellulosic derivatives in polypropylene ma-trix. The microfiltration membranes (polypropylene hollow fibers) were impregnated with solu-tions of some cellulosic derivatives: cellulose acetate, 2-hydroxyethyl-cellulose, methyl 2-hydroxyethyl-celluloseand sodium carboxymethyl-cellulose. The obtained membranes were characterized in terms of the separation performance of the amino acids considered (retention, flux, and selectivity) and from a morphological and structural point of view: scanning electron microscopy (SEM), high resolution SEM (HR-SEM), Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDS) and thermal gravimetric analyzer (TGA). The re-sults obtained show that phenylalanine has the highest fluxes through all four types of mem-branes, followed by methionine and alanine. Of the four kinds of membrane, the most suitable for recuperative separation of the considered amino acids are those based on cellulose acetate and methyl 2-hydroxyethyl-cellulose.

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Soto-Salcido, L. A., I. Anugwom, L. Ballinas-Casarrubias, M. Mänttäri y M. Kallioinen. "NADES-based fractionation of biomass to produce raw material for the preparation of cellulose acetates". Cellulose 27, n.º 12 (29 de mayo de 2020): 6831–48. http://dx.doi.org/10.1007/s10570-020-03251-1.

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Abstract Waste biomass (agave bagasse) and native birch wood were used as raw materials for a novel fractionation and derivation process to produce cellulose acetates (CAs). During the first stage of the fractionation process, a significant amount of hemicelluloses and lignin were dissolved from the biomass using a natural deep eutectic solvent (NADES) that consisted of a mixture of choline chloride and lactic acid with the molar ratio of 1:9. Then, the residual solid material was delignified by bleaching it with a mixture of acetic acid and sodium chlorite. The fractionation process generated differently purified pulps (celluloses) which were converted to CAs. The crystallinity index, polymerization degree, chemical composition, and thermal properties of the differently purified pulps and CAs were analyzed to evaluate the efficacy of the acetylation process and to characterize the CAs. The chemical derivation of the differently purified cellulose samples generated CAs with different degrees of substitution (DSs). The more purified the cellulose sample was, the higher its DS was. Moreover, some differences were observed between the acetylation efficiencies of birch and agave bagasse. Typically, cellulose purified from birch by treating it with NADES followed by bleaching was acetylated more completely (DS = 2.94) than that derived from agave bagasse (DS = 2.45). These results revealed that using green solvents, such as NADES, to treat both agave bagasse (waste biomass) and birch wood, allowed pure fractions to be obtained from biomass, and thus, biomass could be valorized into products such as CAs, which present a wide range of applications.

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Danilevicius, Almantas, Justina Dobiliene, Christoph Wutz y Jolanta Liesiene. "Phenoxyhydroxypropylhydroxyethylcellulose—new amphiphilic cellulose derivative". Cellulose 14, n.º 4 (3 de enero de 2007): 321–29. http://dx.doi.org/10.1007/s10570-006-9105-9.

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Zhou, Xuesong y Yong Huang. "Cellulose derivative-based cholesteric networks". Journal of Applied Polymer Science 96, n.º 5 (2005): 1648–53. http://dx.doi.org/10.1002/app.21617.

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Simon, Mathilde, René Fulchiron y Fabrice Gouanvé. "Water Sorption and Mechanical Properties of Cellulosic Derivative Fibers". Polymers 14, n.º 14 (12 de julio de 2022): 2836. http://dx.doi.org/10.3390/polym14142836.

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In this study, water vapor sorption, desorption properties and tensile mechanical properties of four cellulosic fibers, cotton (C), flax (F), viscose (V) and cellulose acetate (CA), were determined. The sorption and desorption isotherms were modeled using the Park model, which allowed an accurate fitting on the whole range of water activity. This model corresponds to a multi-sorption mode dividing in three sorption modes: Langmuir sorption, Henry’s law and water clustering. Park’s parameters were compared for the sorption and desorption isotherms for each fiber. Regardless of the fiber, differences between sorption and desorption were obtained only for the Henry sorption. The obtained sorption properties were correlated to the accessibility and the amount of sorption sites and also to the crystallinity level of the fibers. It was found that V exhibited the highest water sorption capacity due to a higher hydroxyl groups accessibility and a low amorphous fraction, followed by F, C and CA. Results from tensile tests demonstrated that F and C fibers were more rigid, more resistant and less ductile than CA and V fibers due to a difference of microstructure of the fibers. Finally, the presence of water-sorbed molecules led to a decrease in tensile modulus due to plasticization phenomenon.

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Putri, Margaretha Efa, Anis Yohana Chaerunisaa y Marline Abdassah. "Cellulose Nanocrystals Preparation as Pharmaceuticals Excipient : a Review". Indonesian Journal of Pharmaceutics 2, n.º 2 (4 de marzo de 2020): 42. http://dx.doi.org/10.24198/idjp.v2i2.26422.

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Cellulose nanocrystals is a cellulose derivates which has been widely researched and observed as an chemical agent. Different with cellulose that has been widely used as pharmaceutical excipient especially in solid dosage form, cellulose in nanocrystals form is not available in pharmaceutical grade. Cellulose nanocrystals have different characteristics and quality which is depend on its preparation including sourcing, isolation procedure, and hydrolysis reaction involved. This difference is very important to deeply observed its impact in pharmaceutical dosage form with different active ingredients. In addition, cellulose nanocrystals should meet FDA requirement as pharmaceutical excipient. This review describe cellulose nanocrystals preparation and its characteristics, its application to active pharmaceutical ingredients, and its properties in order to meet FDA requirement.Keywords: Cellulose, nanocrystals, pharmaceutical excipient

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Tesis sobre el tema "Derivati cellulosa"

De, Matos Fernandes Susana. "Novel materialsbased in chitosan, its derivates and cellulose fibers". Pau, 2010. http://www.theses.fr/2010PAUU3010.

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L’objectif de cette étude est de développer de nouveaux matériaux à base de chitosane, de ses dérivés et de fibres de cellulose, sous la forme de nanofibres ou de feuille de papier. Des échantillons de chitosane purifié ont été utilisées afin de préparer les films nanocomposites transparents à base de chitosane (CH) comme matrice (deux chitosanes avec différentes masses molaires et leurs dérivés solubles dans l'eau) et de cellulose nanofibrillaire (NFC) ou de cellulose bactérienne (BC). Les films obtenus sont très transparents; ils affichent de meilleures propriétés mécaniques que ceux à base de chitosane seul. Une autre démarche a consisté à revêtir des feuilles de papier à base d’E. Globulus avec le chitosane ou deux dérivés de chitosane, l'un fluorescent et l'autre soluble dans l'eau. Tout d'abord, un dérivé du chitosane fluorescent a été déposé couche par couche sur des feuilles de papier et sa distribution,a été évaluée. Les résultats montrent que, que la répartition en surface est très homogène et que la pénétration du chitosane dans les pores du papier cesse après un dépôt de trois couches, au-delà une augmentation de l'ensemble de ses épaisseurs et aptitude filmogène. Ensuite, l'effet du chitosane et de son dérivé soluble dans l'eau sur les propriétés finales des papiers a été étudié. En général, chitosane et le chitosane soluble dans l'eau ont un impact positif sur les propriétés finales des papiers couchés. Finalement, la chitine et le chitosane ont été convertis en polyols visqueux à travers une réaction d'oxypropylation simple , dans le but de valoriser les fractions les moins nobles ou les sous-produits de ces précieuses ressources renouvelables
The purpose of this study was to develop new materials based on chitosan and its derivatives and cellulose, in the form of nanofibres or paper sheet. . Chitosan samples were then used to prepare transparent nanocomposite films based on different chitosan (CH) matrices (two chitosans with different DPs and corresponding water-soluble derivatives) and nanofibrillated cellulose (NFC) and bacterial cellulose (BC). The films obtained were shown to be highly transparent, displayed better mechanical properties than the corresponding unfilled chitosan films and showed increased thermal stability. Another approach involved the coating of E. Globulus based paper sheets with chitosan and two different chitosan derivatives, a fluorescent and a water-soluble derivative, on a pilot-size press machine. First, a fluorescent chitosan derivative was deposited layer-by-layer onto conventional paper sheets and its distribution was assessed. The results showed that the surface distribution was highly homogeneous and the penetration of chitosan within the paper pores ceased after a three-layer deposit, beyond coating only produced an increase in its overall thickness and film-forming aptitude. Then, the effect of chitosan and chitosan quaternization on the final properties of chitosan-coated papers was investigated. In general, both chitosan and water-soluble chitosan coatings had a positive impact on the final properties of the coated papers. Finally, chitin and chitosan were converted into viscous polyols through a simple oxypropylation reaction, with the aim of valorizing the less noble fractions or by-products of these valuable renewable resources

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Ecker, Felix F. "Entwicklung schmelzextrudierter Arzneiformen auf Basis von Ether- und Ester-Derivaten der Cellulose /". Berlin : Logos-Verl, 2001. http://www.gbv.de/dms/bs/toc/325417393.pdf.

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Petzold, Matthias [Verfasser], Cordt [Akademischer Betreuer] Zollfrank, Volker [Gutachter] Sieber y Cordt [Gutachter] Zollfrank. "Bioinspirierte Catechol-Derivate der Cellulose / Matthias Petzold ; Gutachter: Volker Sieber, Cordt Zollfrank ; Betreuer: Cordt Zollfrank". München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1162621168/34.

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Candido, Rafael Garcia. "Utilização da celulose de resíduos lignocelulósicos para obtenção de produtos de alto valor agregado". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/97/97131/tde-22082013-161627/.

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Como conseqüência do aumento da produção de cana nos últimos anos, ocorreu o aumento da quantidade de resíduos agroindustriais gerados a partir deste processo, sendo os principais a palha e o bagaço da cana-de-açúcar. O potencial de produção desses resíduos representa em média 14% da massa da cana processada. A celulose é o principal constituinte desses materiais e pode dar origem a outros materiais por meio de reações de derivatização. Entre os derivados de celulose mais importantes, estão os éteres e os ésteres de celulose. A celulose também pode ser fragmentada, a fim de se utilizar seu monômero formador, a glicose. O presente trabalho teve como objetivo extrair a celulose da palha e do bagaço de cana para utilizá-la na produção de dois derivados, o acetato de celulose e a carboximetilcelulose, além de fragmentá-la a glicose, visando a estudar a hidrólise enzimática necessária para produção de etanol celulósico. Para isso, foram testadas duas vias de obtenção da celulose, uma via denominada ácida e outra, denominada alcalina. Ao término de cada etapa das vias, os materiais produzidos foram caracterizados quimicamente com a finalidade de se elucidar o que acontecia em cada etapa. Ao final dos dois processos, o material obtido foi submetido às reações de acetilação e de carboximetilação. Os derivados de celulose foram caracterizados quanto aos seus graus de substituição e por FTIR. Com o acetato de celulose, foram produzidas membranas através de dois métodos distintos, a evaporação de solvente e a inversão de fases. Essas membranas foram caracterizadas fisicamente por MEV, DMA e teste de permeabilidade. Elas também foram testadas quanto à remoção de íons cobre em solução em estado estacionário. Todos os materiais obtidos nas duas vias testadas foram hidrolisados enzimaticamente utilizando-se as enzimas Celluclast 1.5L e ?-glicosidase. Em todas as vias estudadas e para os dois materiais analisados, foram obtidos como produtos finais, materiais com alto teor de celulose (em torno de 90%) e baixo de teor de lignina (menor que 4%), sendo a via alcalina considerada a de melhor desempenho, pois ocorreu menor perda de celulose nessa via do que na via ácida. Foram produzidos acetatos de celulose com grau de substituição 3, ou seja, triacetatos, ideais para a produção de membranas. Contudo, a presença da lignina, mesmo em pequena quantidade, não permitiu que fossem produzidas membranas com alta resistência mecânica. Em geral as membranas foram capazes de remover cerca de 15,0% dos íons cobres em uma solução aquosa. Dos dois métodos estudados, o de inversão de fases foi o que produziu as melhores membranas. Quanto à carboximetilcelulose, foram produzidas CMCs de diferentes características e mais uma vez a lignina interferiu no processo, quanto mais lignina possuía o material antes da produção de CMC, menor foi o grau de substituição obtido. Nas reações de hidrólise enzimática, quanto mais puro era o material em relação ao teor de celulose, maior foi a concentração de glicose no hidrolisado, sendo alcançadas concentrações em torno de 85,00%.
As a consequence of sugarcane increased production in recent years, there was an increased of residues generation from this process, being the straw and bagasse the main ones. The production potential of these wastes represents around 14% of the processed sugarcane mass. Cellulose is the main constituent of these materials and may give rise to other materials by derivatization reactions. Among the most important derivatives of cellulose, are ethers and esters of cellulose. Cellulose can also be fragmented in order to use its monomer, the glucose. The present work aims at extracting the cellulose from sugarcane straw and bagasse to use it in the production of two derivatives, cellulose acetate and carboxymethylcellulose and to fragment it into glucose for studying the enzymatic hydrolysis, which is a required step for ethanol cellulosic production. For this, it was tested two pathways of cellulose obtaining, the acid route and the alkaline route. At the end of each stage of the process, the materials were characterized chemically in order to elucidate what occurred in each step. After finishing both processes, the material was subjected to reactions of acetylation and carboxymethylation. The cellulose derivates were characterized physically for its degree of substitution and for FTIR. The cellulose acetate was utilized to produce membranes through two different methods, the solvent evaporation and the phase inversion. The membranes were characterized for MEV, DMA and permeability test. They were also tested for cooper ions removal. All materials produced at both pathways were hydrolyzed enzymatically for the enzymes Celluclast 1.5L and ?-glucosidase. In all cases, the final material presented high level of cellulose (about 90,0%) and low level of lignin (low than 4,0%). The alkaline route can be considered the one which achieved the best results, since it was in this pathway that the lowest cellulose lost occurred. The cellulose acetates presented a degree of substitution 3, in other words, they are triacetates, ideal for membrane production. Nevertheless, the presence of lignin, even in low amount, did not allow producing membranes with high mechanic resistance. In general, the membranes were able to remove about 15,0% of cooper ions in a aqueous solution. Between the methods carried out, the phase inversion was the one which produced membranes with the best properties. In relation to carboxymethylcellulose, it was obtained CMCs with different characteristics and, once more, the lignin interfered in the process. The more lignin content before CMC production, the less degree of substitution obtained. In the reactions of enzymatic hydrolysis, the highest cellulose purity proportioned the highest glucose concentrations in the hidrolysates, and it was reached conversion values around 85,00%.

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Cittadini, Anna Maria Roberta. "Development and characterization of regenerated cellulose membranes: from a biopolymer derivative to a microfiltration product". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/24999/.

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Membranes, starting from natural to industrial ones, have a fundamental role in many fields as thin barrier with characteristic permeate selectivity. For protection, separation or filtration, the membrane use increased significantly in the past century. In the last years, the possibility to obtain membranes from renewable material started to be a priority. This work focuses on the production of regenerated cellulose membranes, starting from cellulose derivative. The use of this raw material represents an important starting point in the realization of a sustainable product. Regenerated cellulose suits well filtration of aqueous solution, removal of impurities and separation treatments. The advantages of regenerated cellulose use are several: natural origin, available in large quantities, biocompatibility and biodegradability. The aim of this work is to improve an industrial manufacturing process of microfiltration membranes with required features. Particular attention is given to hydrolysis, fundamental step in order to eliminate substituent groups and maintain a stable structure. The raw materials and the competitor samples were characterized in order to realize a precise and detailed starting point for the study. Many variables were taken into consideration: the thickness of the membrane and the possibility of casting supported or not supported films.The effect of polymer concentration in the solution was studied. The influence of the solution formation temperature, the percentage of additive for pores formation and the different coagulation bath composition, have also been analyzed. Several analytical techniques were adopted in order to evaluate the previously described characteristics. The hydrolysis was conducted with a basic solution. The studies carried out have made it possible to identify a timing and a concentration suitable for the complete elimination of the substituent groups and, at the same time, for the maintenance of the membrane stability.

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Chiba, Ryotaro. "Ion-mediated Control of Supramolecular Structure and Optical Properties of a Liquid-crystalline Cellulose Derivative". Kyoto University, 2009. http://hdl.handle.net/2433/123980.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第14668号
農博第1750号
新制||農||968(附属図書館)
学位論文||H21||N4441(農学部図書室)
UT51-2009-D380
京都大学大学院農学研究科森林科学専攻
(主査)教授西尾嘉之, 教授中坪文明, 教授木村恒久
学位規則第4条第1項該当

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Rohowsky, Juta. "Synthese und Charakterisierung neuartiger Cellulosederivate und deren Einsatz als Verkapselungsmaterialien". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-169486.

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Neuartige Cellulosederivate werden ausgehend von kommerziellen Celluloseethern synthetisiert. Aufgrund der guten Löslichkeit der Celluloseether in polaren Lösungsmitteln erfolgt eine homogene Reaktionsführung, wodurch eine regelmäßige Verteilung der Sulfatgruppen entlang der Polymerkette gewährleistet wird. Durch Variation der Reaktionsparameter wie Sulfatierungsmittel, Lösungsmittel, Reaktionszeit und -temperatur erfolgte die Synthese zahlreicher Celluloseethersulfate mit unterschiedlichen Eigenschaften bezüglich Sulfatierungsgrad und kinematischer Viskosität. Durch Bestimmung des Schwefelgehaltes und entsprechender Berechnungen konnten die Anzahl der Sulfatgruppen im Molekül (DSSul) ermittelt werden, wobei die Werte für die synthetisierten Proben im Bereich zwischen DSSul = 0.1 bis DSSul = 2.7 lagen. Der Abbau der Polymerkette wurde ebenfalls durch die Reaktionsbedingungen gesteuert, sodass sowohl Produkte mit hohen (1698 mm2/s) als auch sehr niedrigen (2 mm2/s) kinemtischen Viskositäten resultierten. Wasserlöslichkeit der Produkte wurde durch Trübungsmessungen von 1%igen wässrige Lösungen und der daraus erhaltenen geringen Trübungswerte (NTU < 10) ermittelt. Die Funktionalisierung der Celluloseether mit Sulfatgruppen konnte mittels spektroskopischer Methoden nachgewiesen werden. In 13C-NMR-Spektren von Hydroxypropylcellulosesulfaten wurden zusammen-hängende strukturelle Veränderungen mit dem Anstieg des DSSul der Produkte korreliert. Durch charakteristische Signale im Bereich der Ether-Kohlenstoffatome und deren Verschiebung wurde belegt, dass die Sulfatierung des Celluloseethers an den freien Hydroxylgruppen der Etherseitenkette erfolgte. Mittels FT-RAMAN-Spektroskopie konnten für Sulfatgruppen charakteristische Banden der in den Spektren der sulfatierten Celluloseether nachgewiesen und zugeordnet werden. Aufgrund der ionischen Sulfatgruppen dissoziieren die Celluloseethersulfate in Wasser in geladene Polymerketten. Dadurch ist in Gegenwart von kationischen Polyelektrolyten (polyDADMAC) die Bildung von Polyelektrolytkomplexen in Form von Kapseln und Folien/Membranen möglich. Die Fähigkeit solcher Polyelektrolytkapseln aus Celluloseethersulat und polyDADMAC zu Verkapselung von Substanzen und deren anschließende Freisetzung wurde am Beispiel der Verkapselung des Fluoreszenzfarbstoffes Rhodamin B gezeigt. Mittels fluoreszenzspektroskopischer Messungen konnte der aus den Kapseln freiwerdende Farbstoff detektiert werden. Anhand der Messungen wurde gezeigt, dass die Farbstofffreigabe im Fall von Rhodamin B abhängig von den Probeneigenschaften ist. Durch die Wahl des Ausgangsstoffes und deren Funktionalisierung mit Sulfatgruppen kann die Farbstofffreisetzung gesteuert werden. Mit zunehmendem DSSul des Celluloseethersulfates verlängert sich die Verweilzeit des Fluoreszenz-farbstoffes in der Kapsel. Zusätzliche Funktionelle Gruppen in der Seitenkette des Ausgangsstoffes führen zu sterischen Hinderung bei der Wechselwirkung mit polyDADMAC, wodurch eine gegenseitige Durchdringung der Polymerketten bei der Ausbildung des Polyelektrolytkomplexes gehindert wird, sodass weniger kompakte Membranstrukturen der Kapseln resultieren. In Zellexperimente mit adhärenten Zelllinien an entsprechenden mit Celluloseethersulfat präpartierten Oberflächen wurde gezeigt, dass die Zelladhäsion durch den Sulfatierungsgrad der Proben beeinflusst wird. Auf Proben mit höherem Sulfatierungsgrad findet eine verbesserte Adhäsion im Vergleich zu Proben statt, die einen geringen Sulfatierungsgrad aufweisen. Demnach wird die Kompatibilität der Zellen auf solche Oberflächen durch die Erhöhung des Substitutionsgrades der Proben begünstigt.

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Hildenbrand, Claudia. "Nanostructured carbons from cellulose-derivative-based aerogels for electrochemical energy storage and conversion : evaluation as EDLC electrode material". Paris, ENMP, 2010. http://pastel.archives-ouvertes.fr/pastel-00547497.

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Les carbones nanostructurés sont très largement utilisés dans les systèmes de stockage et conversion d'énergie par voie électrochimique, par exemple en tant que matériau d'électrode de pile à combustible et de batterie ou encore de supercondensateur. La structure du carbone ainsi que sa chimie de surface sont des paramètres primordiaux et doivent être adaptés aux différentes spécificités de chacune de ces applications. Dans ce cadre général, cette thèse a pour but de développer une nouvelle famille de carbones nanostructurés, les aérogels de carbone cellulosiques. Ces derniers sont obtenus par pyrolyse d'aérogels organiques élaborés à partir d'acétate de cellulose. Pour ce faire, nous avons fait varier les paramètres de synthèse sol-gel ainsi que les conditions de séchage et de pyrolyse (principalement la composition du sol, la nature du catalyseur, la température et l'atmosphère de pyrolyse) afin de générer une vaste palette de structures. Dans un second temps, ces aérogels ont subi différents post-traitements visant à modifier leur chimie de surface et ce, par introduction de groupements fonctionnels oxygénés et azotés. Finalement, les Performances de ces nouveaux aérogels de carbone ont été analysées sous la forme de matériaux d'électrode de supercondensateur
Nanostructured carbons are widely used in electrochemical energy storage and conversion devices, e. G. As electrode material for fuel cells, batteries, or still EDLCs (Electric Double Layer Capacitor). The carbon structure and surface chemistry are crucial parameters and consequently need to be adjusted to the specific application's requirements. This PhD thesis has aimed at developing a new family of nanostructured carbons: aerogels from renewable organic sol-gel precursors, i. E. Pyrolyzed cellulose-acetate-based aerogels. Sol-gel synthesis parameters and drying conditions of the organic gel, as well as pyrolysis parameters (particularly the influence of the sol composition, the type of catalyst used in the sol-gel synthesis step, pyrolysis temperature, and atmosphere) have been varied systematically in order to generate a broad range of structurally different cellulose-acetate-based carbonaceous aerogels. Further, cellulose-acetate-based carbon aerogels have been exposed to different post-treatments (e. G. Introduction of oxygen and nitrogen-containing surface functional groups) to create cellulose-acetate-based carbon aerogels with different surface chemistries. Finally, the performance of these cellulose-acetate-based carbon aerogels has been analyzed as EDLC electrode material

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Klein, Manuela Poletto. "Imobilização de β-galactosidase para obtenção de produtos lácteos com baixo teor de lactose". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/24803.

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A β-galactosidase (E.C 3.2.1.23) é uma das enzimas mais empregadas na indústria de alimentos sendo utilizada na hidrólise da lactose. Neste trabalho foram utilizadas duas metodologias para imobilização desta enzima. Na primeira delas foi empregado como suporte um material híbrido à base de sílica que possui um grupo orgânico catiônico covalentemente ligado. A adsorção da enzima a este material apresentou eficiência que variou de 74 a 53% com o aumento da quantidade de enzima aplicada ao suporte. A baixa estabilidade térmica da enzima imobilizada obtida e as prováveis fracas interações envolvidas na sua adsorção a este suporte podem explicar o decréscimo de atividade observada durante as sucessivas bateladas de hidrólise da lactose. Na primeira batelada o grau de hidrólise foi de 90,9% e no final da última batelada (4ª), a enzima foi capaz de converter apenas 13% do substrato. A segunda metodologia utilizada foi imobilização covalente da enzima em um filme de celulose/líquido iônico modificado com uma poliamina e ativado com glutaraldeído. A presença da poliamina foi confirmada por análises de infravermelho. Após a imobilização, a enzima reteve 60% de sua atividade inicial. Bons resultados de hidrólise da lactose em batelada foram obtidos tanto a 7ºC como a 35ºC e foi possível reutilizar a enzima imobilizada por 16 ciclos consecutivos, a 7ºC, sem mudanças significativas na atividade enzimática. O valor de Km para a enzima imobilizada no material híbrido à base de sílica foi de 9,17 mM e para a enzima imobilizada nos filmes de celulose foi de 11,22 mM, ambos apresentaram um acréscimo quando comparados ao Km enzima livre (1,25 mM), devido à dificuldade de acesso do substrato ao sítio ativo da enzima. Não houve mudança no pH e temperatura ótimos da enzima imobilizada em relação à enzima livre em nenhum dos métodos testados.
β-galactosidase (E.C 3.2.1.23) is the most widely used enzymes in the food industry and its employed in the lactose hydrolysis process. In this study, two methodologies were used to test their immobilization. In the first, the enzyme was immobilized by adsorption in one silica based hybrid material that contains a cationic organic group covalently linked. The efficiency of immobilization showed a decrease of 74 to 53% by increasing the protein load applied to the support. The low thermo stability of the immobilized enzyme and the probable weak interactions involved in their adsorption, could explain the decrease in enzyme activity observed in the successive batch hydrolysis of lactose. In the first run, the degree of lactose hydrolysis was 90.9% and, at the end of the last run (4th), the enzyme was able to convert only 13% of the substrate. The second methodology used was the covalent immobilization of the enzyme on a cellulose/ionic liquid film, modified with a polyamine and activated using glutaraldehyde. The presence of a polyamine was confirmed by infrared analysis. After immobilization, the enzyme retained 60% of its initial activity. Highly efficient lactose conversion was achieved in a batch process at 7ºC and 35ºC and was possible to reuse the immobilized enzyme in 16 repeated cycles, at 7ºC, without any drastic decrease in enzyme activity. Km value for the immobilized enzyme in silica based hybrid material was 9.17 mM and for the enzyme immobilized in the film of cellulose/ionic liquid was 11.22 mM, both showing an increase compared with the Km value for free enzyme (1.25 mM), due to the difficulty of access of the substrate to the active sites of the enzyme. The immobilized enzyme did not show any changes in the optimal pH and temperature when compared to the free enzyme in both methods tested.

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Capítulos de libros sobre el tema "Derivati cellulosa"

Onofrei, Mihaela Dorina, Adina Maria Dobos y Silvia Ioan. "Processes in Cellulose Derivative Structures". En Nanocellulose Polymer Nanocomposites, 355–91. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118872246.ch14.

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"cellulose derivative". En The Fairchild Books Dictionary of Textiles. Fairchild Books, 2021. http://dx.doi.org/10.5040/9781501365072.2803.

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Christensen, B. E., B. T. Stokke y O. Smidsrød. "Xanthan—The natural water soluble cellulose derivative". En Cellulose and Cellulose Derivatives, 265–78. Elsevier, 1995. http://dx.doi.org/10.1533/9781845698539.4.265.

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James, S. G., J. Schatzle, V. Tsakalos, E. Peuvrel-Disdier y P. Navard. "Flow-induced structures in isotropic and anisotropic cellulose derivative blends". En Cellulose and Cellulose Derivatives, 393–400. Elsevier, 1995. http://dx.doi.org/10.1533/9781845698539.5.393.

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"Electro-optical Properties of Cellulose Derivative Composites". En Polysaccharides, 1143–60. CRC Press, 2004. http://dx.doi.org/10.1201/9781420030822-51.

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Figueirinhas, J., P. Almeida y M. Godinho. "Electro-optical Properties of Cellulose Derivative Composites". En Polysaccharides. CRC Press, 2004. http://dx.doi.org/10.1201/9781420030822.ch47.

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Vshivkov, Sergey y Elena Rusinova. "Phase Transitions and Structure of Liquid Crystalline Cellulose Ether Solutions in a Magnetic Field and in Its Absence". En Liquid Crystals [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.101451.

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The results of research studies of a magnetic field effect on structure and phase transitions of liquid crystalline polymer systems are described. Influence of intensity of the magnetic field, molecular weight, and concentration of polymers in solutions on the phase diagrams is analyzed. The dependences of boundary curves on the chemical structure of polymers and solvents are discussed. Results of theoretical researches of the magnetic field effect on the diamagnetic macromolecule orientation in solutions are described. The shift of boundary curves of liquid crystalline cellulose derivative systems is compared with the energy of magnetic field stored by solutions.

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Muratore, Florencia, María L. Goñi, Luis Serrano, Jalel Labidi, Silvia Barbosa y Raquel Martini. "Development of Bioactive Paper by Capsaicin Derivative Grafting Onto Cellulose". En Biopolymer Grafting: Synthesis and Properties, 199–233. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-323-48104-5.00005-6.

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Adelani Alabi, Kazeem, Rasheed Adewale Adigun, Ibrahim Olasegun Abdulsalami y Mariam Dasola Adeoye. "Furfural: A Versatile Derivative of Furan for the Synthesis of Various Useful Chemicals". En Furan Derivatives - Recent Advances and Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.100303.

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Furfural, a five-membered heterocyclic aromatic hydrocarbon derivable from acid hydrolysis of sugar cane bagasse, maize cob, rice husk or any cellulose-containing material, is useful in the synthesis of a range of specialized chemical products. Its condensation with nitromethane in basic medium yields 2-(2-Nitrovinyl) furan. This functional group (nitrovinyl) has been documented as a potent anti-microbial agent against gram-positive and gram-negative bacteria, with more potency against the gram-positive strains. The reaction of urea and thiourea with furfural yields bisimines-1,3-bis[(E)-furan2-yl)methylene]urea, and 1,3-bis[(E)-furan-2-yl) methylene]thiourea respectively. The two compounds are good antimicrobial agents in addition to the latter as a potential dye for wool and cotton fabrics with different hues. Also the reaction between acetophenone and furfural (an aldehyde) in a basic medium yields the chalcone: (E)-3-(furan-2-yl)-1-phenylprop-2-ene-1-one. This chalcone has been confirmed as a good antifungal agent and wood-protector against termite attack. Thus, chemical modification of the aldehyde functional group of furfural to nitro, imine and chalcone groups imparted different activities on furfural.

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"Carbonyl Dyes and Pigments". En Colour Chemistry, 99–132. 2^a ed. The Royal Society of Chemistry, 2014. http://dx.doi.org/10.1039/bk9781849733281-00099.

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The chemical class of colorants that is second in importance to azo dyes and pigments is characterized by the presence of a carbonyl (CO) group, which may be regarded as the essential chromophoric unit. A substantial part of this chapter is devoted to anthraquinones, the most important group of carbonyl dyes and pigments. In contrast to azo dyes, carbonyl dyes are found in nature; dyes such as indigo and alizarin – an anthraquinone derivative – are amongst the most important natural dyes for textiles. Synthetic carbonyl dyes and pigments are capable of providing a wide range of colours, essentially covering the entire visible spectrum. In terms of fastness properties, carbonyl dyes and pigments are often superior to their azo counterparts, often making them the colorants of choice when high technical performance is demanded. A particular textile application class dominated by carbonyl dyes is the vat dye class, a group of dyes applied to cellulosic fibres such as cotton. The ability of the carbonyl groups to undergo reduction to a water-soluble form which is capable of transferring to the fibre, and subsequently re-oxidised to its original system, is utilized. In this chapter the characteristic structural features of the most important types of carbonyl colorants are reviewed and an overview of some of the more important synthetic routes is presented.

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Actas de conferencias sobre el tema "Derivati cellulosa"

Guan, Wenchao, Gang Ke, Changyu Tang y Yifeng Liu. "Study on Lubrication Properties of Carboxymethyl Cellulose as a Novel Additive in Water-Based Stock". En World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-64250.

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This paper reports cellulose derivative—carboxymethyl cellulose (CMC) as a novel additive in a water-based stock (water content above 95 wt.%). Cellulose is one of the richest renewable resources on earth and has many peculiar qualities. Several cellulose derivatives such as CMC can easily dissolve in water and form stable thin film on the surface of metal. Several apparatus involving four-ball machine were used to investigate lubrication properties of the based stock containing CMC. The worn surfaces were observed with a scanning electron microscope. As the results, the anti-wear ability of the base stock is effectively increased by addition of a small amount (0.7 wt.%) of CMC. The additive with peculiar molecular structure contributes to abate the adhesion and scuffing of frictional pair effectively, hence improves the antiwear ability of the base stock. Thus CMC provides a potential application in the field of water-based stock lubrication.

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Miyagawa, Atsushi, Maria Carmelita Z. Kasuya, Kenichi Hatanaka y Koji Matsuoka. "SYNTHESIS OF POLYACRYLAMIDE CARRYING GLOBOTRIOSE DERIVATIVE FOR IMMOBILIZATION ON CELLULOSE MATERIALS". En XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.624.

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Ben, Wang, Liu yanjie y Dai chuanbo. "REVIEW ON THE REGENERATION, DERIVATION AND DEGRADATION OF CELLULOSE IN IONIC LIQUID SYSTEM". En International Conference on New Materials and Intelligent Manufacturing. Volkson Press, 2018. http://dx.doi.org/10.26480/icnmim.01.2018.58.61.

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KIM, HONGHYUN, YEOUNSOO KIM, KWINAM PARK, SEOK-HEUNG JANG, SEOUNMOON LEE y JINWON PARK. "THE SEPARATION OF MODIFIED CELLULASE WITH POLYALKYLENE OXIEDE DERIVATE USING REACTIVE AQUEOUS TWO PHASE SYSTEM". En Proceedings of the 4th International Conference. WORLD SCIENTIFIC, 2004. http://dx.doi.org/10.1142/9789812702623_0148.

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Karlovits, Igor. "Lignocellulosic bio-refinery downstream products in future packaging applications". En 10th International Symposium on Graphic Engineering and Design. University of Novi Sad, Faculty of technical sciences, Department of graphic engineering and design,, 2020. http://dx.doi.org/10.24867/grid-2020-p2.

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The concept of efficient utilisation of renewable bio-based materials (biomass feedstock) is the driving force in the green transformation to a more sustainable and circular society. Biorefineries or biochemical platforms convert and utilise different sources of biomass into fuels and other beneficial derivates like fibres and other bio-based chemicals. These can be used as building blocks for many potentially useful applications. In this review, we shall describe the current state of the art and trends in the conversion of lignocellulosic feedstock into materials which can be primarily used in packaging applications. The three main constituents (cellulose, hemicellulose and lignin) are being re-engineered into new products with higher added value. The main goal of all these downstream products is that they do not compete with animal feed and food applications. The main downstream products of different kind of transformations are different natural fibres which can be further processed into micro or nano fibrillated state and used for a broad application of fields from ink, adhesive and packaging materials. Also, fibres and its derivates can be bonded successfully into bio-composites or fibre-based foams applications for the protective packaging applications. Hemicellulose, as a second most abundant component, has been researched for applications in adhesives and paper and paperboard coatings. Lignin which is currently utilised as an energy source for the paper industry, has been recently actively researched. Lignin-based biopolymers have a potential to be used in many different applications from additives in the barrier coatings on the packaging to active packaging and even as lignin-based foams. All these applications are currently in the development stages and cover niche market segments, but are expected to grow and to be used in future markets.

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