Download or read book Polyelectrolyte Adsorption on Wood Fibers written by Joanna Lee Koethe and published by . This book was released on 1992 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Polyel e ctrolyte Adsorption on Wood Fibers written by Ajay Kumar and published by . This book was released on 1998 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effects of Cellulosic Fiber Charges on Polyelectrolyte Adsorption and Fiber fiber Interactions written by A. Elisabet Horvath and published by . This book was released on 2006 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: The surface charges of cellulosic fibers contribute to several papermaking operations that influence the manufacture and final properties of paper. This thesis investigates the effect of the surface charges on wet-end chemistry, e.g. through the interaction of cationic polyelectrolytes with the fiber surface charges, and on the network strength of pulp suspensions. The polyelectrolyte titration method was used to investigate the interaction of the fiber charges with cationic polyelectrolytes. Techniques were developed to fluorescent label the adsorbing cationic polyelectrolyte in order to visualize the adsorption behavior. Fluorescent confocal laser scanning microscopy (CLSM) was used to determine the extent to which the cationic polyelectrolyte adsorbs into the porous fiber wall. It was shown that the polyelectrolyte charge density limits the adsorption to the surface under electrolyte-free conditions. Adsorption into the fiber wall only occurs for two conditions: 1) if the molecular mass is sufficiently low or 2) the electrolyte concentration is high enough to screen the charges along the polyelectrolyte backbone but not the interactions between the polyelectrolyte and the fiber charges.Aside from the polyelectrolyte properties, the fiber charge density contributes to the adsorption behavior of cationic polyelectrolytes. The fiber charge profile was altered by bulk and surface carboxymethylation. The electrolyte concentration at which a deviation from 1:1 stoichiometry occurs was shown to be dependent on the amount of surface charges, such that the deviation in stoichiometry occurs at a higher electrolyte concentration for pulps having a higher surface charge. A hypothesis was developed to test the conditions at which the deviation in adsorption stoichiometry occurs, which was defined as the critical electrolyte concentration (CEC). It was found that the CEC corresponded to the electrolyte concentration at which the distance between the fiber charges was on the order of the Debye length. Electron spectroscopy for chemical analysis (ESCA) was used as an independent calibration procedure to validate for which a 1:1 stoichiometry occurs. The analysis with ESCA agreed well with the polyelectrolyte titration method for measurement of fiber surface charges. When measured under appropriate conditions, i.e. electrolyte concentration and molecular properties, the fiber surface charge can accurately be measured by the polyelectrolyte titration method.The charge profiles of various pulp types and treatments were also examined. Having been established as a valid technique, the polyelectrolyte titration method was again used to measure the surface charge while conductometric titration was used to measure the total charge content. The amount of bulk and surface charges vary depending on the pulping method and type of wood, although the ratio between the bulk and surface charge (i.e. the charge ratio) is similar for chemical pulps. The mechanical pulp has a higher charge ratio because it contains more fines material than chemical pulp. Bleaching of the chemical pulp decreases the amount of bulk and surface charges, although the charge ratio remains essentially constant. However, methods such as beating or carboxymethyl cellulose (CMC) grafting are available to increase the charge ratio.The effect of the charge profile on fiber-fiber interactions was studied on both a microscopic and macroscopic level. Colloidal probe microscopy (CPM) was used to investigate the microscopic interactions between two cellulose surfaces. Cellulose surfaces, prepared by spin-coating a dissolving pulp onto silica, were used to model the fiber surface, which is too rough for surface force measurements. The charge density of the model surface was increased by CMC grafting. Results showed that increasing the surface charge density created large electrosteric repulsions, due to CMC the chains protruding out from the surface. These interactions on the microscopic scale affect the fiber network strength, which was measured with a parallel plate rheometer. When the repulsion is increased between the fibers, caused by the increase in the surface charge, fiber flocs break apart more easily due to a reduced friction between the fiber surfaces.The forces acting on the fiber network can also be mechanical in origin. The fiber length and flexibility were altered in order to study the influence of mechanical surface linking and elastic fiber bending on the fiber network strength. Using the storage modulus (G'0) as a measure of fiber network strength, longer fibers were found to create a stronger network due to an increased amount of fiber contacts. Flexible fibers have a lower network strength than stiff fibers because the fibers come to rest in a less strained position such that the the influence of elastic fiber bending on the fiber network strength is predominant.

Download or read book Polyelectrolyte Adsorption on Cellulose Fibres written by and published by . This book was released on 2001 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Polyelectrolyte Adsorption on Packed Beds of Pulp Fibers written by Laura Ciovica and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lignocellulosic Fibers and Wood Handbook written by Mohamed Naceur Belgacem and published by John Wiley & Sons. This book was released on 2016-04-14 with total page 699 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will focus on lignocellulosic fibres as a raw material for several applications. It will start with wood chemistry and morphology. Then, some fibre isolation processes will be given, before moving to composites, panel and paper manufacturing, characterization and aging.

Download or read book Polyelectrolyte Complexes in the Dispersed and Solid State II written by Martin Müller and published by Springer. This book was released on 2013-08-23 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polyelectrolyte Complexes for Tailoring of Wood Fibre Surfaces. Polyelectrolyte Complexes in Flocculation Applications. Spontaneous Assembly and Induced Aggregation of Food Proteins. Polyelectrolyte Complexes of DNA and Polycations as Gene Delivery Vectors. Sizing, Shaping and Pharmaceutical Applications of Polyelectrolyte Complex Nanoparticles.

Download or read book Analytical Methods in Wood Chemistry Pulping and Papermaking written by Eero Sjöström and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: In its broadest sense, and according to the traditional conception, wood chemistry is a comprehensive discipline, ranging from fundamental studies to practical applications. The manifold constituents, located in different morphological regions in the wood, results in an extreme complexity of wood chemistry. Ever more sophisticated endeavors needing fundamental studies and advanced analytical methods are necessary in order to delve deeper into various problems in pulping and papermaking. Gradually, new, improved ana lytical methods, originally developed for research purposes, are currently replacing many of the old "routine" methods in practical applications. Because of the expanse of the subject, an attempt to write a book of this size about analytical methods seems, perhaps, too ambitious. Of course, a whole book series of several volumes would be necessary to cover this topic completely. However, there is undoubtedly a need for a more condensed presentation which does not go into experimental details, but is limited to the basic principles of the analytical methods and illustrates their applica tions. The emphasis is on more advanced and potential methods, and partic ularly on those based on different types of spectroscopy and chromatography.

Download or read book Tailoring Fibre and Paper Properties Using Physical Adsorption of Polyelectrolytes written by and published by . This book was released on 2012 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Nanoscience and Technology of Renewable Biomaterials written by Lucian A. Lucia and published by John Wiley & Sons. This book was released on 2009-07-23 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: The unique nanoscale properties of renewable biomaterials presentvaluable opportunities in the field of nanoscience and technology.Lignocellulosic biomass is an important industrial resource whichcan be used for the production of highly efficient andenvironmentally sustainable nanomaterials. The Nanoscience and Technology of Renewable Biomaterialspresents the latest advances in biomass nanotechnology, includingleading research from academia and industry, as well as a futurevision for the nanotechnology of forest products. Topics covered include: A fundamental review of the relationship betweennanotechnology and lignocellulosic biomass Characterization methods for biomass on the nanometerscale Cellulose, hemicelluloses and lignin as nanoscopicbiomaterials-physical features, chemical properties and potentialnanoproducts Nanoscale surface engineering Renewable materials as scaffolds for tissue engineering Nanoscopically-controlled drug delivery This book will be a valuable resource for chemists, chemicalengineers, bioscience researchers and materials scientists who areinterested in harnessing the nanotechnological features ofrenewable biomaterials.

Download or read book On the Adhesion Between Substrates Covered with Polyelectrolyte Multilayers written by Rikard Lingström and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis examines the formation of Polyelectrolyte Multilayers (PEM) on cellulose fibres as a new way of influencing the fibre surface and the adhesion between wood fibres. The aim of the study was to enhance the fundamental understanding of the adsorption mechanisms behind the formation of Polyelectrolyte Multilayers on cellulose fibres; to study how the properties of the layers can be influenced and to show how the properties of the layers influence the adhesion between the fibres and the strength of paper sheets made from the PEM treated fibres. Different polyelectrolyte systems are known to form PEMs with different properties, and in this work two different polymer systems were extensively studied: poly(dimethyldiallylammonium chloride) (PDADMAC) / poly(styrene sulphonate) (PSS), which are both strong polylectrolytes (i.e. are highly charged over a wide range of pH) and poly allylaminehydrochloride (PAH) /poly acrylic acid (PAA), which are both weak polyelectorlytes (i.e. sensitive to pH changes). PEMs were also formed from PAH/ poly(3,4-ethylenedioxythiophene):PSS (PEDOT:PSS), in order to form electrically conducting PEMs on fibres and PEM-like structures were formed from polyethylene oxide (PEO) and polyacrylic acid (PAA). (...).

Download or read book Competitive Adsorption of Poly 1 vinylpyrrolidone co styrene and Kymene 557H Onto Wood Fibers written by Ronald W. Maurer and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Non-ionic copolymers, such as poly(1-vinylpyrrolidone-co-styrene), are used in the production of filtration membranes and fibers because of their ability to provide both hydrophilic and hydrophobic character. However, their non-ionic character and solubility in water prevents inexpensive recovery from waste streams. Wood fibers show potential as recovery agents because they are inexpensive, environmentally friendly, and have a large surface area per unit mass (200 m2/g). However, due to the anionic nature of the fiber surface, their adsorptive behavior is often limited to cationic species. We have shown that low-dosage application of a cationic polyamide epichlorohydrin resin, Kymene 557H, using a sequential adsorption process can alter the fiber surface charge so as to provide more neutral surface area for the non-ionic polymer to adsorb; furthermore, the adsorbed Kymene 557H does not block the approach of poly(1-vinylpyrrolidone-co-styrene). Single-component adsorption of poly(1-vinylpyrrolidone-co-styrene) was on the order of 10-3 g/g; with Kymene 557H adsorbed on the fiber, the adsorption increased one order of magnitude to 10-2 g/g. This significant increase is caused by neutralization of fiber surface charge via Kymene 557H adsorption, creating a surface more favorable for adsorption and recovery of non-ionic species.

Download or read book The Creation of Antibacterial Fibres Through Physical Adsorption of Polyelectrolytes written by Josefin Illergard and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Contact-active antibacterial surfaces with irreversibly attached antibacterial com-pounds are a sustainable alternative to traditional biocides. No chemicals are released into nature and the antibacterial mechanism reduces the risk of the evolution of re-sistant bacteria. However, the preparation of such surfaces is far from sustainable, as organic solvents and harsh reaction conditions commonly are required. An alter-native option is to use polyelectrolyte multilayers (PEM), based on physical ad-sorption, which can be performed in water-based solutions at room temperature. Although contact-active antibacterial PEMs have been reported previously, this is the first study of renewable cellulosic wood fibres. The build-up of cationic polymer polyvinylamine (PVAm) and anionic polyacrylic acid (PAA) multilayers on model surfaces was studied to optimise adsorption. The amount of adsorbed polyelectrolytes was continuously growing with increasing number of layers, but remained dense and flat as the number of layers increased. The largest adsorption was obtained at a high salt concentration, which shielded the repulsion between the polymers. Model surfaces were also used to evaluate the influence of the polymer and number of layers on the antibacterial properties. Multilayers on model surfaces showed a low bacteriostatic effect, with up to approximately 40 % inhibition for 3 layers of un-modified PVAm/PAA. In contrast, when the same multilayers were applied on cel-lulosic fibres, bacterial-growth inhibition of > 99.9% was obtained. Hydrophobically modified PVAm did not yield better results, despite being superior in solution. An increase in fibre charge by fibre oxidation led to the largest amount of adsorbed pol-ymer and the best antibacterial properties, an effect that lasted for weeks. (...).

Download or read book Paper Chemistry and Technology written by Monica Ek and published by Walter de Gruyter. This book was released on 2009 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The production of forestry products is based on a complex chain of knowledge in which the biological material wood with all its natural variability is converted into a variety of fiber-based products, each one with its detailed and specific quality requirements. This four volume set covers the entire spectrum of pulp and paper chemistry and technology from starting material to processes and products including market demands. Supported by a grant from the Ljungberg Foundation, the Editors at the Royal Institute of Technology, Stockholm, Sweden coordinated over 30 authors from university and industry to create this comprehensive overview. This work is essential for all students of wood science and a useful reference for those working in the pulp and paper industry or on the chemistry of renewable resources."--Publisher's description.

Download or read book Adsorption of Polyelectrolytes and Polymer induced Flocculation of Cellulosic Fibers written by Lars Wågberg and published by . This book was released on 1987 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Kinetics of Polyelectrolyte Adsorption on Cellulosic Fibres written by and published by . This book was released on 2000 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sustainability of Biomass through Bio based Chemistry written by Valentin I Popa and published by CRC Press. This book was released on 2021-03-22 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: The process of photosynthesis is a potential source of energy and bioproducts. Renewable sources of polymeric materials offer an answer to maintaining sustainable development of economically and ecologically attractive technology. The innovations in the development of materials from biopolymers, preservation of fossil-based raw materials, complete biological degradability, reduction in the volume of garbage and compostability in the natural cycle, climate protection through reduction of carbon dioxide released, and the application possibilities of agricultural resources for the production of bio/green materials are some of the reasons why such materials are attracting public interest. FEATURES Discusses waste from urban areas, forestry and agricultural processes, specifically grown crops such as trees, starch crops, sugar crops hydrocarbon plants and oils, and finally aquatic plants such as water seaweeds and algae, which can be used as raw materials for sustainable development. Presents recent advances in the development of some specifically chemical components of biomasses for a sustainable future. Focuses on lignocellulose as a source of bio-based products. Draws upon expertise from various countries. Describes how upgraded and integrated biomass processing may reduce the risks associated with the COVID-19 pandemic. Valentin I. Popa is professor emeritus of Wood Chemistry and Biotechnology at Gheorghe Asachi Technical University of Iasi, Romania.