Effect of Temperature and Molecular Weight on the Rheology of Concentrated Polymer Solutions PDF Download

Author: Gerald Anthony Bullano
Publisher:
ISBN:
Category : Polymers
Languages : en
Pages : 460

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Author: William David Richards
Publisher:
ISBN:
Category : Polymers
Languages : en
Pages : 184

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Author: Rupesh Bhatia
Publisher:
ISBN:
Category :
Languages : en
Pages : 202

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Book Description
An experimental study has been conducted to understand the rheological behavior of several non-newtonian polymeric liquids. A constant stress/strain rheometer with cone and cylinder geometry is used to determine the variation of shear stress (and hence apparent viscosity) with shear rate. A number of non-newtonian polymeric liquids that consist of carefully prepared aqueous solutions of Hydroxyethylcellulose (HEC), Polyethyleneoxide (PEO), Carboxymethylcellulose (CMC), Xanthan gum, and Polyacrylic acid (Carbopol) are used in this study. In order to ascertain the effect of molecular mass of the polymers on the apparent viscosity variation with shear rate, different grades of each polymer are used. The tests are done for varying concentrations and temperatures (23-80 deg C) to determine their requisite effects on rheology. Also, intrinsic viscosity of each polymeric liquid is obtained by using an Ubbelohde capillary tube viscometer. This characterizes the inherent capacity of each polymer to alter its solutions viscosity. Depending upon the polymer and its concentration, the results show both shear-thinning behavior with shear rate as well as time-dependent (thixotropy) effects. Time-dependent effects, which are found to be a strong function of concentration and temperature, are evaluated by measuring viscosity by first increasing and successively decreasing the shear rates. The zero-shear viscosity and shear-thinning effects are seen to decrease with concentration. In general for most polymers, high temperatures decrease the viscosity of the solution, with the exception of Carbopol for which the viscosity is seen to increase slightly with temperature and then decrease at even higher temperatures. Carbopol polymers also show thixotropic effects at higher temperatures which are significant at 80 deg C. They further exhibit yield stress at higher concentrations and no yield stress is noticed at lower concentrations. A number of models described in the literature are used to fit the rheological data. It is noticed that the modified power-law model, Sisko model and Herschel Bulkley model are insufficient approximations of the asymptotic forms and hence, could not be used to describe the rheological behavior of all the polymers. The appropriately modified and redefined asymptotic forms of all these models are used to correctly fit the data for various polymers. The variation of the different model parameters with changes in concentration and temperature are quantified, and a detailed comparative study on the effects of molecular mass, concentration, and temperature on rheological properties is presented.

Author: Jose Luis Rivera Armenta
Publisher: BoD – Books on Demand
ISBN: 1789840015
Category : Science
Languages : en
Pages : 186

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Book Description
Rheology is the science that studies the behavior of the flow of matter in a liquid state or soft solids under the application of stress or deformation to obtain a response to an applied force. In polymers, rheology is an important tool to understand behavior under processing conditions and to design equipment. Another application for rheology in the polymer field is to understand structure-property relationships by means of molecular weight, molecular weight distribution, stereochemistry, morphology, melt degradation, and performance under processing. This book covers the essential criteria for selecting the best test types for various applications and new developments, for accurately interpreting results, and for determining other areas where rheology and rheological phenomena may be useful in your work.

Author: Lawrence E. Nielsen
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 222

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Author: A.A. Collyer
Publisher: Springer Science & Business Media
ISBN: 9781851665570
Category : Technology & Engineering
Languages : en
Pages : 494

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Author: American Chemical Society. Meeting
Publisher:
ISBN:
Category : Language Arts & Disciplines
Languages : en
Pages : 368

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Best known for their use as bulk materials, polymers when used in small amounts as rheology modifiers can convert simple fluids to high-performance materials. Such additives have found use in paints and coatings, fuels and lubricating oils, cosmetics and personal care products, and food. This 20-chapter book presents a strong mix of industrial and academic contributions that cover rheological concepts, gels and latices, associating polymers, polymer-polymer and polymer-solvent interactions, and deformation-related orientations.

Author: Edward T. Severs
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 200

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Author: Keith Ko-kung Chao
Publisher:
ISBN:
Category :
Languages : en
Pages : 816

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Book Description

Author: B.R. Gupta
Publisher: CRC Press
ISBN: 1000789799
Category : Technology & Engineering
Languages : en
Pages : 463

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Book Description
This book covers a wide range of topics in polymer rheology. These are: Basic Principles, parameters, systems and applied mathematical models used in the rheological studies Melt flow analysis of different non-Newtonian fluids in laminar flow, transition between laminar and turbulent flow and modified Reynolds number The effects of different physical and molecular parameters on purely viscous rheological response of polymer melts and solutions Principles of rheometery and different types of viscometers and on-line rheometers The static and dynamic viscoelastic response of the polymer melts and solutions, viscoelasticity, mechanical models and Boltzmann superposition principle Molecular structure – viscoelasticity relationship and linear and non-linear viscoelasticity Effects of different processes, materials parameters like temperature, fillers (micro and nano-fillers) and molecular parameters like MW, MWD The role of rheology in polymer processing in different equipment Modified power law constants and two range power law constants for a large number of polymers, rheology software program in Java, comparison of different polymer rheological models using the rheology software and answers to the problems The book will be very useful to both undergraduate and postgraduate students, as well as teachers and practicing rheologists.