Download or read book The Effect of Shear on Colloidal Aggregation and Gelation Studied Using Small angle Light Scattering written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigated the effect of shear on the structure and aggregation kinetics of unstable colloids using small angle light scattering. We used an aqueous suspension of 20 nm polystyrene latex microspheres and MgCl2 to induce aggregation. The sample was only sheared once for approximately 33 seconds at different times, typically 1 min., 5 min., or 15 min., after the onset of aggregation. The average shear rate was in the range of 0.13 - 3.56 s[negative superscript 1], which was in a laminar regime. The unsheared sample gelled after ca. 45 min. When the sample was sheared soon after the onset of aggregation, the aggregation followed DLCA kinetics to yield D[subscript f]= 1.80 [plus or minus] 0.04 aggregates unaffected by the shear. The gel time also remained the same as the unsheared gel. Shearing at later stages of aggregation shortened the gel time and enhanced the scattered light intensity significantly indicating rapid growth. Then, depending on the shear rate, there were three different behaviors. At high shear rates, the aggregate structure was inhomogeneous after the shear was stopped with a crossover in slope in the scattered light intensity vs. q, to imply hybrid superaggregates with two different fractal dimensions. At intermediate shear rates far from the gel point, there was a similar crossover after the shear was stopped; however, the fractal dimension regained 1.80 [plus or minus] 0.04 at the gel point. At low shear rates, the aggregation rate was increased, but the aggregate structure was uniform, and the fractal dimension remained 1.75 [plus or minus] 0.05.

Download or read book Studies of the Effects of Shear on Colloidal Aggregation and Gelation Using Small Angle Light Scattering written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigated the effect of shear on the structure and aggregation kinetics of unstable colloids using small angle light scattering. We used an aqueous suspension of 20 nm polystyrene latex microspheres and MgCl[subscript]2 to induce aggregation. The sample was only sheared once for approximately 33 sec at different times, typically 1 min, 5 min, or 15 min, after the onset of aggregation. The average shear rate was in the range of 0.13 - 3.56 sec[superscript]-1, which was in a laminar regime. The unsheared sample gelled after ca. 45 min. When the sample was sheared soon after the onset of aggregation, the aggregation followed the diffusion limited cluster cluster aggregation (DLCA) kinetics to yield D[subscript f] = 1.80 [plus or minus] 0.04 aggregates unaffected by the shear. The gel time also remained the same as the unsheared gel. Shearing at later stages of aggregation shortened the gel time and enhanced the scattered light intensity significantly indicating rapid growth. Then, depending on the shear rate, there were three different behaviors. At high shear rates, the aggregate structure was inhomogeneous after the shear was stopped with a crossover in slope in the scattered light intensity versus q, to imply hybrid superaggregates with two different fractal dimensions. At intermediate shear rates far from the gel point, there was a similar crossover after the shear was stopped; however, the fractal dimension regained 1.80 [plus or minus] 0.04 at the gel point. At low shear rates, the aggregation rate was increased, but the aggregate structure was uniform, and the fractal dimension remained 1.75 [plus or minus] 0.05.

Download or read book Aggregation and Gelation of Concentrated Colloidal Suspensions written by Sara Romer and published by Herbert Utz Verlag. This book was released on 2001 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Time resolved Investigation of Aggregation and Gelation of Colloids written by Ronny Vavrin and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2009-08 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work we present a study of the aggregation and sol-gel transition of colloidal suspensions using a wide range of experimental techniques. We investigate in the first part of this work a model system which undergoes a sol-gel transition in the hope to gain further insight into the fundamental process of gelation. Therefore, a colloidal suspension of nano particles (polystyrene spheres) in water is destabilised to induce aggregation of fractal clusters. The clusters will grow until they finally all connect and form a gel. Combining neutron and light scattering, we are able to measure simultaneously and time resolved the static and dynamic properties of the same sample, which allows us to test well-known theories and to compare our data with recent results of other research groups. Our measurements demonstrate a deviation from classical theories in the critical behavior just before the gel is formed, which we interpret as a glassy cluster phase. The second part of this work describes an experimental setup which is based on a multiple scattering suppression scheme and which allows us to measure even relatively turbid samples faster and with higher precision.

Download or read book Time resolved Investigation of Aggregation and Sol gel Transition in Colloidal Suspensions written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work we present a study of the aggregation and sol-gel transition of colloidal suspensions using a wide range of experimental techniques, where some of them were modified or developed especially for this purpose. Covering all relevant time and length scales, we investigate in the first part of this work a model system which undergoes a sol-gel transition in the hope to gain further insight into the fundamental process of gelation. Therefore, a colloidal suspension of nano particles (polystyrene spheres) in water is destabilised to induce aggregation of fractal clusters. The clusters will grow until they finally all connect and form a volume filling network, i.e. a gel. Combining neutron and light scattering, we are able to measure simultaneously and time resolved the static and dynamic properties of the same sample in the length scale of a few Angstroms to several hundred nanometers, which allows us to test well-known theories and to compare our data with recent results of other research groups. Our measurements demonstrate a deviation from classical theories in the critical behavior just before the volume spanning network is formed, which we interpret with the observation of a glassy cluster phase. In order to investigate this effect, a novel technique is used to gain access to very slow dynamic processes, revealing data which seems to proof our hypothesis of a glassy phase in the gelation process. The second part of this work describes an experimental setup which is based on a light scattering technique introduced in the last ten years and which allows us to measure faster and with higher precision. By measuring simultaneously at four different angles instead of only one, a factor of four in acquisition time is gained in comparison to traditional setups. Moreover, dynamic measurements can be analysed angle dependent and therefore improved in precision. As the chosen technique is based on a multiple scattering suppression scheme, even relatively turbid samp.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soft Matter Characterization written by Redouane Borsali and published by Springer Science & Business Media. This book was released on 2008-07-28 with total page 1490 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 2-volume set includes extensive discussions of scattering techniques (light, neutron and X-ray) and related fluctuation and grating techniques that are at the forefront of this field. Most of the scattering techniques are Fourier space techniques. Recent advances have seen the development of powerful direct imaging methods such as atomic force microscopy and scanning probe microscopy. In addition, techniques that can be used to manipulate soft matter on the nanometer scale are also in rapid development. These include the scanning probe microscopy technique mentioned above as well as optical and magnetic tweezers.

Download or read book Handbook of Food Structure Development written by Fotis Spyropoulos and published by Royal Society of Chemistry. This book was released on 2019-10-31 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most useful properties of food, i.e. the ones that are detected through look, touch and taste, are a manifestation of the food’s structure. Studies about how this structure develops or can be manipulated during food production and processing are a vital part of research in food science. This book provides the status of research on food structure and how it develops through the interplay between processing routes and formulation elements. It covers food structure development across a range of food settings and consider how this alters in order to design food with specific functionalities and performance. Food structure has to be considered across a range of length scales and the book includes a section focusing on analytical and theoretical approaches that can be taken to analyse/characterise food structure from the nano- to the macro-scale. The book concludes by outlining the main challenges arising within the field and the opportunities that these create in terms of establishing or growing future research activities. Edited and written by world class contributors, this book brings the literature up-to-date by detailing how the technology and applications have moved on over the past 10 years. It serves as a reference for researchers in food science and chemistry, food processing and food texture and structure.

Download or read book Suspensions of Colloidal Particles and Aggregates written by Frank Babick and published by Springer. This book was released on 2016-04-04 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the properties of particles in colloidal suspensions. It has a focus on particle aggregates and the dependency of their physical behaviour on morphological parameters. For this purpose, relevant theories and methodological tools are reviewed and applied to selected examples. The book is divided into four main chapters. The first of them introduces important measurement techniques for the determination of particle size and interfacial properties in colloidal suspensions. A further chapter is devoted to the physico-chemical properties of colloidal particles—highlighting the interfacial phenomena and the corresponding interactions between particles. The book’s central chapter examines the structure-property relations of colloidal aggregates. This comprises concepts to quantify size and structure of aggregates, models and numerical tools for calculating the (light) scattering and hydrodynamic properties of aggregates, and a discussion on van-der-Waals and double layer interactions between aggregates. It is illustrated how such knowledge may significantly enhance the characterisation of colloidal suspensions. The final part of the book refers to the information, ideas and concepts already presented in order to address technical aspects of the preparation of colloidal suspensions—in particular the performance of relevant dispersion techniques and the stability of colloidal suspensions.

Download or read book Gels written by and published by . This book was released on 1995 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Clay Minerals and Synthetic Analogous as Emulsifiers of Pickering Emulsions written by Fernando Wypych and published by Elsevier. This book was released on 2022-08-13 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: Clay Minerals and Synthetic Analogous as Emulsifiers of Pickering Emulsions begins with basic concepts of Pickering emulsions, describes the thermodynamic, kinetic and gravitational stability, the methods of preparation, and the most common characterization techniques. Next, the book presents detailed structure, properties, and physical-chemical modifications of natural and synthetic layered minerals to optimize its properties. Figures and schemes are prepared for experts in the area as well as the undergraduate and graduate students from many different research areas where clay minerals, synthetic layered materials and Pickering emulsion have potential applications. Clay Minerals and Synthetic Analogous as Emulsifiers of Pickering Emulsions fills a gap in the literature, stimulates the aggregation of value of clay minerals, and shows the readers the methods of preparation, characterization, and applications of Pickering emulsions stabilized with layered materials, giving special attention to clay minerals. - Fills a gap in the literature with multidisciplinary coverage of Pickering Emulsions - Presents methods of preparation, characterization, and applications of Pickering emulsions for clay minerals - Includes contributions from top experts in the relevant fields

Download or read book Kinetics of Aggregation and Gelation Proceedings of the International Topical Conference on Kinetics of Aggregation and Gelation Held at Athens Georgia on 2 4 April 1984 written by F. Family and published by . This book was released on 1984 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Partial Contents: Fractal Concepts in Aggregation and Gelation: An Introduction; On the Aggregative Fractals Called Squigs, which Include Recursive Models of Polymers and of Percolation Clusters; Theory of Fractal Growth Processes; Self-similar Structures and the Kinetics of Aggregation of Gold Colloids; Electrostatic Aggregation and Interface Dynamics; Properties of Growing Interface in Diffusion-Limited Aggregation and in the Eden Process; Oscillations and Scaling in a Kinetic Gelation Model; Kinetic Gelation with a Constant Initiator Creation Rate; Measuring Red Cell Aggregation Kinetics with Nuclear Magnetic Resonance; Monte Carlo Simulation of Vulcanization; Cluster Numbers From the Potts Model; A Small-Angle Neutron Scattering Study of the Decomposition of Fe-28Cr-10.5 Co; Aggregation of Colloidal Silica; Mean Field Theory for a Ballistic Model of Aggregation; Particle-Cluster Aggregation with Fractal Particle; Scaling Properties of Growth by Kinetic Clustering ; Computer Simulations of Domain Growth; Random-Field Ising Model: Domain Growth Theory; The Elasticity and Vibrational Modes of Percolating Networks and Other Fractal Structures; Kinetics of Red Blood Cell Aggregation: An Example of Geometric Polymerization; Frequency Spectrum of an Elastic Sierpinski Gasket; Growth of Clusters During Inhibition in a Network of Capillaries; Experimental Analysis of Diffusion Controlled Coagulation Using an Optical Purse Particle Size Analyzer.

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2018 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Particle Shape on the Structure and Rheology of Colloidal Suspensions and Gels written by Ali Mohraz and published by . This book was released on 2004 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Maro Polymer Notes written by and published by . This book was released on 1997 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Light Scattering from Polymer Solutions and Nanoparticle Dispersions written by Wolfgang Schärtl and published by Springer Science & Business Media. This book was released on 2007-08-13 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Light scattering is a very powerful method for characterizing the structure of polymers and nanoparticles in solution. As part of the Springer Laboratory series, this book provides a simple-to-read and illustrative textbook probing the seemingly very complicated topic of light scattering from polymers and nanoparticles in dilute solution, and goes further to cover some of the latest technical developments in experimental light scattering.

Download or read book Theory and Applications of Colloidal Suspension Rheology written by Norman J. Wagner and published by Cambridge University Press. This book was released on 2021-04-15 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Essential text on the practical application and theory of colloidal suspension rheology, written by an international coalition of experts.