Download or read book Cellulose Interaction with Cationic Polyelectrolyte written by Jielong Su and published by . This book was released on 2015 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: Paper engineering of strength, structure and surface using interactions between cellulose and cationic polyelectrolytes are investigated with the aim of improving paper-based bio-analytical devices (PADs). Advances are described based on fundamental knowledge and engineering aspects in this field that have enable the development of lighter weight papers that have high wet strengths, controlled porosities and multi-functional properties that can be fine tuned.The influence of reactive cationic polyelectrolyte, polyamideamine-epichlorohydrin (PAE) on paper strength behaviour was studied using hardwood fibers, both with and without inorganic electrolyte. Ion type and concentration in the papermaking process water was found to influence the strength development in different ways. The relationship between repulpability of PAE- strengthened paper and wet strength is described. The effect of blending microfibrillated cellulose (MFC) with hardwood fibers is compared with the refining of hardwood fibers on paper composite properties, with and without PAE addition. Papers incorporating tethered MFC, produced by refining of hardwood fibres, are found to provide equivalent strength properties to papers incorporating untethered MFC with significant drainage benefits and formation uniformity. Air permeability of the composites decreases with untethered and tethered MFC addition.MFC achieved by ball milling and cellulose micro-particles (CMPs) developed by cryogenic milling softwood fiber are compared with commercial MFC produced by homogenization. The effect of blending two MFCs and CMPs with hardwood fibers on the paper composites properties is investigated in terms of nano/micro cellulose dimensions. CMPs act as mechanical debonding agents and decrease substrate density and strength whereas MFC have higher aspect ratios and smaller size distributions that significantly improve strength and density of composite sheets while decreasing porosities. The addition of MFC combined with PAE can increase both dry and wet strength. The different stress-strain curves under wet conditions are described and these suggest two different mechanisms of strength development: MFC-fiber entanglement and fiber-fiber contact reinforcement.The role of paper macroscale properties and structure are described in PADs used to type human red blood cells (RBCs). A series of commercial and laboratory-generated papers varying in fibre composition, basis weight, density and porosity are studied and their abilities to separate antibody agglutinated (specific) from non-agglutinated (non-specific) RBCs are reported. Image analysis is used to measure the intensities of blood spots produced by sequentially absorbing solutions of antibodies and blood samples on paper then eluting with a saline solution. The performance of these papers in blood typing is found to decrease linearly with paper density and thickness and it is inversely proportional to paper pore size. The type of fibres plays a minor role. Porous cellulose webs modified with cationic polyelectrolyte further optimize blood typing analysis.Cellulose model surfaces, in the form of quasi molecularly smooth thin cellulose films, are investigated to examine the interactions between cellulose, cationic polyelectrolytes and biomolecules. Thin smooth cellulose films are prepared by spin coating either a nanocellulose crystal suspension, or a cellulose acetate solution onto silicon surfaces with subsequent hydrolysis. Film smoothness is greatly improved by controlling the concentration of cellulose acetate and the hydrolysis time in methanolic sodium methoxide. High molecular weight polyacrylamides (CPAM) are used as model polyelectrolytes, and the nanoscale conformation of adsorbed CPAM at the cellulose/water interface is characterized in situ by specular neutron reflectometry. The effect of CPAM charge density and added NaCl (10-3 M) is described. At constant molecular weight, the thickness of the CPAM layer adsorbed on cellulose increases with polymer charge density. Addition of NaCl decreases the thickness of a CPAM layer already adsorbed on cellulose. However the thickness of the adsorption layer on cellulose of a CPAM solution pre-equilibrated in NaCl is much higher, because the re-shrunk polymer coils do not relax as much upon adsorption.Deuterated cellulose film having better contrast for neutron reflectometry is investigated. Incorporation of deuterium into bacterial cellulose is achieved by growing Gluconacetobacter xylinus - strain ATCC 53524 in a mixture of deuterated glucose and deuterated glycerol. Two strategies are compared for synthesizing deuterated cellulose derivatives that are soluble in volatile solvents (acetone and toluene) suitable for spin coating: one involves acetylation in acetic anhydride, the other trimethylsilylation in ionic liquid (1-butyl-3-methylimidazolium chloride). The trimethylsilylation of deuterated cellulose results in a much higher yield of product, and is used to prepare toluene solutions for spin-coating onto smooth flat silicon substrates. The resulting thin film is hydrolysed back to deuterated cellulose using hydrogen chloride vapour.The data generated is used to prepare improved substrate papers for use in PADs with high wet strength, controlled structure and fine-tuned surface properties.

Download or read book Complex Formation Between Cationic Cellulose Polymers and Oppositely Charged Surfactants in Aqueous Media written by Sudhaa Srinivasan and published by . This book was released on 2009 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT:Mixtures of polymers and surfactants are widely used in aqueous media to provide structure, solubilization domains, and/or colloidal stability. Underlying these functions are inter- and intra-molecular interactions that depend on the nature of the polymers and the type of surfactants. We have investigated here the phase behavior of cationic cellulose derivatives in aqueous media upon addition of oppositely charged surfactant, sodium dodecyl sulfate (SDS). The solution behavior and interactions between the polyelectrolyte and the surfactant can be profoundly affected by the polyelectrolyte charge density and hydrophobic modification, as well as by the presence in water of polar organic solvents (cosolvents).

Download or read book Cationic Polyelectrolyte Fate and Effect in Dewatering of Cellulose Sludge written by Nancy Jean Griskowitz and published by . This book was released on 1993 with total page 208 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 Cationic starches on cellulose surfaces written by Henrica G. M. Steeg (van de) and published by . This book was released on 1992 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Enhanced Enzymatic Hydrolysis of Cellulosic Fibers by Cationic Polyelectrolytes written by John Timothy Reye and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A new method for enhancing rates of enzymatic hydrolysis for cellulosic fiber is presented. By adding a cationic polyelectrolyte to a cellulase/cellulose hydrolytic system, the polyelectrolyte binds to the cellulase and fiber forming flocs. The cellulase is bound by a patching mechanism. By using this technique, the rate of enzymatic hydrolysis can be enhanced. This thesis covered observations made about the cellulase/cationic polyelectrolyte/fiber interactions. A mechanism was proposed based on the experimental results.

Download or read book CATIONIC HYDROXYETHYL CELLULOSE POLYMERS IN AQUEOUS SOLUTIONS written by Poornima Dixit and published by . This book was released on 2009 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixtures of polymers and surfactants are widely used in aqueous media to provide structure, solubilization domains, and/or colloidal stability. Underlying these functions are inter- and intramolecular interactions that depend on the nature of the polymers and the type of surfactants. We have investigated here the phase behavior of cationic Hydroxyethyl cellulose in aqueous media upon addition of oppositely charged surfactants, sodium dodecyl sulfate (SDS) or Standapol ES2. The solution behavior and interactions between the polyelectrolyte and the surfactant can be profoundly affected by the polyelectrolyte charge density and hydrophobic modification, as well as by the presence in water or polar organic solvents (co-solvents).

Download or read book Surface Science and Adhesion in Cosmetics written by K. L. Mittal and published by John Wiley & Sons. This book was released on 2021-04-06 with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt: Activity in the arena of surface chemistry and adhesion aspects in cosmetics is substantial, but the information is scattered in many diverse publications media and no book exists which discusses surface chemistry and adhesion in cosmetics in unified manner. This book containing 15 chapters written by eminent researchers from academia and industry is divided into three parts: Part 1: General Topics; Part 2: Surface Chemistry Aspects; and Part 3: Wetting and Adhesion Aspects. The topics covered include: Lip biophysical properties and characterization; use of advanced silicone materials in long-lasting cosmetics; non-aqueous dispersions of acrylate copolymers in lipsticks; cosmetic oils in Lipstick structure; chemical structure of the hair surface, surface forces and interactions; AFM for hair surface characterization; application of AFM in characterizing hair, skin and cosmetic deposition; SIMS as a surface analysis method for hair, skin and cosmetics; surface tensiometry approach to characterize cosmetic products; spreading of hairsprays on hair; color transfer from long-wear face foundation products; interaction of polyelectrolytes and surfactants on hair surfaces; cosmetic adhesion to facial skin; and adhesion aspects in semi-permanent mascara; lipstick adhesion measurement.

Download or read book Multilayer Thin Films written by Gero Decher and published by John Wiley & Sons. This book was released on 2012-06-11 with total page 1157 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second, comprehensive edition of the pioneering book in this fi eld has been completely revised and extended, now stretching to two volumes. The result is a comprehensive summary of layer-by-layer assembled, truly hybrid nanomaterials and thin fi lms, covering organic, inorganic, colloidal, macromolecular, and biological components, as well as the assembly of nanoscale fi lms derived from them on surfaces. These two volumes are essential for anyone working in the field, as well as scientists and researchers active in materials development, who needs the key knowledge provided herein for linking the field of molecular self-assembly with the bio- and materials sciences.

Download or read book Chemistry of Modern Papermaking written by Cornel Hagiopol and published by CRC Press. This book was released on 2011-09-08 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemistry of Modern Papermaking presents a chemist's perspective on the papermaking process. With roughly 3% of the mass of a paper product invested in water-soluble chemicals, paper makers can adjust the speed and efficiency of the process, minimize and reuse surplus materials, and differentiate a paper product as required by specific customers. W

Download or read book Cellulose and Cellulose Derivatives written by J F Kennedy and published by Elsevier. This book was released on 1995-09-30 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proceedings of the Cellucon Trust conference held in Lund, Sweden, in 1993. The latest scientific advances are covered, environmental concerns and the consequent economic costs are dealt with. The papers have surprisingly wide applications across a number of industries, including food processing, pharmaceuticals, chemical processing, civil engineering and composite materials production.

Download or read book Investigation of the Interactions of Cationic Polyelectrolytes with Anionic Surfactants written by Lisa Renee Huisinga and published by . This book was released on 2008 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soluble Anionic Cellulose Derivatives and Formation of Complexes with Cationic Polyelectrolytes written by B. Philipp and published by . This book was released on 1981 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Polymernanocomposites Processing Performance and Application written by Jitendra K. Pandey and published by Springer Science & Business Media. This book was released on 2014-01-02 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume A of Handbook of Polymer Nanocomposites deals with Layered Silicates. In some 20 chapters the preparation, architecture, characterisation, properties and application of polymer nanocomposites are discussed by experts in their respective fields

Download or read book Structure performance Relationships in Surfactants written by Milton J. Rosen and published by . This book was released on 1984 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Interactions in Polyelectrolyte cellulose Systems and Their Implications for Flocculation Mechanisms written by Jani Salmi and published by . This book was released on 2009 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Nanocellulose and Cellulose Nanocomposites written by Hanieh Kargarzadeh and published by John Wiley & Sons. This book was released on 2017-03-02 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt: An up-to-date and comprehensive overview summarizing recent achievements, the state of the art, and trends in research into nanocellulose and cellulose nanocomposites. Following an introduction, this ready references discusses the characterization as well surface modification of cellulose nanocomposites before going into details of the manufacturing and the self-assembly of such compounds. After a description of various alternatives, including thermoplastic, thermosetting, rubber, and fully green cellulose nanocomposites, the book continues with their mechanic and thermal properties, as well as crystallization and rheology behavior. A summary of spectroscopic and water sorption properties precedes a look at environmental health and safety of these nanocomposites. With its coverage of a wide variety of materials, important characterization tools and resulting applications, this is an essential reference for beginners as well as experienced researchers.