Author: William Joseph Milliken
Publisher:
ISBN:
Category :
Languages : en
Pages : 492

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Book Description

Author: Francisco Chinesta
Publisher: Elsevier
ISBN: 0081008120
Category : Science
Languages : en
Pages : 398

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Book Description
This book provides a review of the current understanding of the behavior of non-spherical particle suspensions providing experimental results, rheological models and numerical modeling. In recent years, new models have been developed for suspension rheology and as a result applications for nanocomposites have increased. The authors tackle issues within experimental, model and numerical simulations of the behavior of particle suspensions. Applications of non-spherical particle suspension rheology are widespread and can be found in organic matrix composites, nanocomposites, biocomposites, fiber-filled fresh concrete flow, blood and biologic fluids. Understand how to model and predict the final microstructure and properties of particle suspensions Explores nano, micro, meso and macro scales Rheology, thermomechanical and electromagnetic physics are discussed

Author: Arjun Sharma
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
Particle suspensions in viscoelastic or polymeric liquids undergo uniaxial extensional and/ or simple shear flows in several industrial and manufacturing processes such as hydraulic fracturing, extrusion molding, or fiber spinning. The resulting interaction of particles and polymers can lead to drastic changes in the suspension rheology, ultimately impacting the process efficiency. This thesis characterizes the fundamental mechanisms of particle-polymer interactions within the two flows mentioned above. It develops methods to study the flows of particle-filled viscoelastic fluids and evaluate the rheology of a dilute suspension in any weakly non-Newtonian fluid. In a uniaxial extensional flow, spherical particles and polymers interact to either increase or decrease the suspension stress due to the regions of highly stretched or collapsed polymers (relative to the polymers undisturbed by the velocity perturbations due to the particle), respectively, in the fluid around the particles. If the polymer relaxation time is large, as is often the case in applications, the polymer collapse happens more rapidly and persists for long times. The magnitude of reduction in suspension stress increases with the polymer relaxation time, the imposed extensional rate, and particle concentration. Therefore, adding only a small amount of particles to a viscoelastic fluid can reduce its extensional viscosity and improve the efficiency of the industrial process. Fibers are added to impart mechanical, electrical, or thermal anisotropy to the final cured product. In a Newtonian fluid, the fibers rotate in degenerate periodic orbits dependent on their initial orientations, making it challenging to obtain aligned particles necessary for obtaining an anisotropic material. Viscoelasticity can, however, break this degeneracy and allow better particle alignment. A theory is developed for slender prolate spheroids rotating in a simple shear flow of low concentration polymeric solution. It is the first theoretical prediction of a wide range of particle orientation behaviors observed in the experiments. Large aspect ratio particles rotating in fluids with a small polymer relaxation time migrate towards a specific small periodic orbit close to the vorticity axis. A stable orientation close to the imposed simple shear flow's flow direction is obtained for a large polymer relaxation time. The theoretical findings lead to a phase diagram of different particle orientation behavior depending on the fluid properties and particle aspect ratio. This can be instrumental in guiding the right choice of parameters in future experiments and in applications to obtain the desired anisotropy. One of the methods used to investigate the extensional rheology at low polymer concentrations is generalized to encompass the characterization of the rheology of any weakly non-Newtonian fluid. It is foreseen that this computationally inexpensive semi-analytical method can be used to guide the design of new fluids for achieving desired rheological properties. The second method is a sophisticated numerical tool that solves the flow of fully viscoelastic fluids around a prolate spheroidal particle, thus covering a range of shapes from a sphere to high aspect ratio fiber in an unbounded fluid. It helps test slender body theories, study a range of linear flows of viscoelastic fluids around an isolated particle and determine various rheologies of dilute particle suspensions.

Author: Richard A. Pethrick
Publisher: CRC Press
ISBN: 9783718651542
Category :
Languages : en
Pages : 430

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Book Description
This volume contains reviews on state-of-the-art Japanese research presented in the annual Spring and Autumn meetings of the Japanese Polymer Science Society. The aim of this section is to make information on the progress of Japanese Polymer Science, and on topics of current interest to polymer scientists in Japan, more easily available worldwide.

Author: Michael A. Turney
Publisher:
ISBN:
Category :
Languages : en
Pages : 474

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Book Description

Author: Suresh G. Advani
Publisher:
ISBN:
Category : Manufacturing processes
Languages : en
Pages : 636

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Book Description
Deals with the mechanics and modelling aspects of discontinuous and continuous fibre composites, and familiarizes engineers with the critical and fundamental issues of material processing and transport phenomena in polymeric composites and their applications in modelling.

Author: Christopher Klein
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832519882
Category : Science
Languages : en
Pages : 249

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Book Description
The influence of shear fields on water-based systems was investigated within this thesis. The non-linear rheological behaviour of spherical and rod-like particles was examined with Fourier-Transform rheology under LAOS conditions. As a model system for spherical particles two different kinds of polystyrene disper- sions, with a solid content higher than 0.3 each, were synthesised within this work. Due to the differences in polydispersity and Debye-length, differences were also found in the rheology. In the FT-rheology both kinds of dispersions showed a similar rise in the intensities of the magnitudes of the odd higher harmonics, which were predicted by a model. The, in some cases additionally appearing second harmonics, were not predicted. A novel method to analyse the time domain signal was developed, that splits the time domain signal up in four characteristic functions. Those characteristic functions correspond to rheological phenomena. In some cases the intensities of the Fourier components can interfere negatively. FD-virus particles were used as a rod-like model system, which already shows a highly non-linear behaviour at concentrations below 1. % wt. Predictions for the dependence of the higher harmonics from the strain amplitude described the non-linear behaviour well at large, but no so good at small strain amplitudes. Ad- ditionally the trends of the rheological behaviour could be described by a theory for rod-like particles. An existing rheo-optical set-up was enhanced by reducing the background birefringence by a factor of 20 and by increasing the time resolution by a factor of 24. Additionally a combination of FT-rheology and rheo-optics was achieved. The influence of a constant shear field on the crystallisation process of zinc oxide in the presence of a polymer was examined. The crystallites showed a reduction in length by a factor of 2. The directed addition of polymers in combi- nation with a defined shear field can be an easy way for a defined change of the form of crystallites.

Author: LEO FLOYD CARTER
Publisher:
ISBN:
Category :
Languages : en
Pages : 121

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Book Description

Author: Arthur S. Lodge
Publisher: Academic Press
ISBN: 1483263355
Category : Technology & Engineering
Languages : en
Pages : 456

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Book Description
Viscoelasticity and Rheology covers the proceedings of a symposium by the same title, conducted by the Mathematics Research Center held at the University of Wisconsin-Madison on October 16-18, 1984. The contributions to the symposium are divided into four broad categories, namely, experimental results, constitutive theories, mathematical analysis, and computation. This 16-chapter work begins with experimental topics, including the motion of bubbles in viscoelastic fluids, wave propagation in viscoelastic solids, flows through contractions, and cold-drawing of polymers. The next chapters covering constitutive theories explore the molecular theories for polymer solutions and melts based on statistical mechanics, the use and limitations of approximate constitutive theories, a comparison of constitutive laws based on various molecular theories, network theories and some of their advantages in relation to experiments, and models for viscoplasticity. These topics are followed by discussions of the existence, regularity, and development of singularities, change of type, interface problems in viscoelasticity, existence for initial value problems and steady flows, and propagation and development of singularities. The remaining chapters deal with the numerical simulation of flow between eccentric cylinders, flow around spheres and bubbles, the hole pressure problem, and a review of computational problems related to various constitutive laws. This book will prove useful to chemical engineers, researchers, and students.

Author: Rajkumar Durairaj
Publisher: BoD – Books on Demand
ISBN: 9535109537
Category : Science
Languages : en
Pages : 117

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Book Description
This book focuses on the current research in the area of rheology. Rheological characterizations are performed on materials in order to understand the basic nature of a system, quality control of raw materials and final products. The rheological characterizations are important to study the effect of different parameters such as formulation, shelf life and temperature on the quality of final products. The book covers a broad range of rheology related topics such as microrheology, capillary rheolgical measurements, characterization of dense suspensions and numerical analysis of viscoelastic fluids.