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Viscoelastic Properties Of Entangled Polymers Iii The Transient Network Model
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Book Synopsis Viscoelastic Properties of Entangled Polymers. III. The Transient Network Model by : S. D. Hong
Download or read book Viscoelastic Properties of Entangled Polymers. III. The Transient Network Model written by S. D. Hong and published by . This book was released on 1977 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: The viscoelastic behavior of entangled polymers is modeled by a three dimensional transient network where the entangled points are considered to act as temporary crosslinks. Polymer chains are represented by beads and springs. The effect of entanglements on chain dynamic are introduced by assigning enhanced frictional coefficients to selected beads, and extra elastic couplings between pairs of the entangled beads. The formation and disengagement of the entanglements can be envisioned to be in a dynamic equilibrium. The strength of elastic coupling is set to decrease with increasing the distance between the entangled points. The resulting modified Rouse-Bueche-Zimm matrix is solved for the relaxation times from which the dynamic moduli, relaxation moduli, steady-state shear compliance, and zero-shear viscosity are computed. Results are in excellent agreement with experimental data on monodisperse polystyrene, poly-alpha-methylstyrene, polyvinyl acetate and polybutadiene. (Author).
Book Synopsis Introduction to Polymer Viscoelasticity by : John J. Aklonis
Download or read book Introduction to Polymer Viscoelasticity written by John J. Aklonis and published by . This book was released on 1983 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: A molecular approach to the fundamentals of viscoelastic behavior in polymers, bridging the gap between introductory accounts and advanced research level monographs. This second edition includes new coverage of the theory of reptation, the kinetic theory of rubber elasticity, and an entirely new chapter on dielectric relaxation. Presents all derivations in detail, and treats concepts and models paying special attention to assumptions, simplifications and limitations. Provides problems at the end of each chapter.
Book Synopsis Introduction to Polymer Viscoelasticity by : Montgomery T. Shaw
Download or read book Introduction to Polymer Viscoelasticity written by Montgomery T. Shaw and published by John Wiley & Sons. This book was released on 2005-08-19 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: A revised molecular approach to a classic on viscoelasticbehavior Because viscoelasticity affects the properties, appearance,processing, and performance of polymers such as rubber, plastic,and adhesives, a proper utilization of such polymers requires aclear understanding of viscoelastic behavior. Now in its third edition, Introduction to Polymer Viscoelasticityremains a classic in the literature of molecular viscoelasticity,bridging the gap between primers on polymer science and advancedresearch-level monographs. Assuming a molecular, rather than amechanical approach, the text provides a strong grounding in thefundamental concepts, detailed derivations, and particularattention to assumptions, simplifications, and limitations. This Third Edition has been entirely revised and updated to reflectrecent developments in the field. New chapters include: * Phenomenological Treatment of Viscoelasticity * Viscoelastic Models * Time-Temperature Correspondence * Transitions and Relaxation in Polymers * Elasticity of Rubbery Networks * Dielectric and NMR Methods With detailed explanations, corresponding equations, andexperimental methods, supported by real-life applications (as wellas the inclusion of a CD-ROM with data to support the exercises),this Third Edition provides today's students and professionals withthe tools they need to create polymers with more desirablequalities than ever.
Book Synopsis Viscoelastic Properties of Blends of "entangled" Polymers by : W. M. Prest
Download or read book Viscoelastic Properties of Blends of "entangled" Polymers written by W. M. Prest and published by . This book was released on 1968 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Viscoelastic Properties of Entangled Polymers. I. The Elastically Coupled Entanglement Model by : David R. Hansen
Download or read book Viscoelastic Properties of Entangled Polymers. I. The Elastically Coupled Entanglement Model written by David R. Hansen and published by . This book was released on 1975 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: The bead-and-spring model of Rouse, Bueche and Zimm is extended to describe the viscoelastic behavior of polymers with chain entanglements. Motion of the macromolecules is retarded by the presence of entanglements with neighboring chains. This effect is in part represented by selected beads along the chain having enhanced friction coefficients. These selected beads may have values of friction coefficients that are uniformly higher than the unentangled beads, or are progressively higher as a function of the position along the chain. Major improvements in the model result when these entangled points are also assumed to be elastically coupled to the surrounding medium. This coupling is modelled by interconnecting the entangled beads with springs having low spring constants. The resulting equations of motion of the model contain a modified Zimm matrix that is nonsymmetrical. The eigenvalues were obtained numerically on the computer to yield the relaxation spectra, permitting calculation of dynamic moduli, relaxation moduli, equilibrium shear compliance and zero-shear viscosity for a series of molecular weights. Agreement with experimental data on monodisperse polystyrene was found to be excellent for all these properties. Of particular interest is the ability of the model to predict the equilibrium shear compliance as a function of molecular weight, which was not achievable by earlier theories. The sensitivity of J suber to the fitting parameters renders it a useful discriminator in selecting the best model for describing chain entanglement effects in polymer viscoelasticity.
Book Synopsis Viscoelastic Properties of Polymers by : John D. Ferry
Download or read book Viscoelastic Properties of Polymers written by John D. Ferry and published by . This book was released on 1961 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Viscoelastic Properties of Entangled Polymer IV. Binary Blends of Monodisperse Homopolymers by : S. D. Hong
Download or read book Viscoelastic Properties of Entangled Polymer IV. Binary Blends of Monodisperse Homopolymers written by S. D. Hong and published by . This book was released on 1978 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a previous publication from this laboratory, the Rouse-Bueche-Zimm molecular theory of viscoelasticity has been extended by using a transient network model to apply to monodisperse polymers with chain entanglements. Effects of the entanglements were modeled both by the enhanced frictional coefficients and by the additional elastic couplings resulting from the transient entanglement network. For binary blends consisting of two monodisperse polymers with different molecular weights, additional modifications are now required to predict their linear viscoelastic behavior. It is recognized that entanglements not only may form between chains of the same lengths, but also between those of different lengths. For the latter case, the longer chain will in fact have the frictional coefficient of the shorter chain at the point of entanglements. The frequency of such interactions is assumed to be proportional to the weight ratio of the repective component chains in the blend. Equations of motion are formulated for each component and solved numerically for the relaxation spectra.
Book Synopsis Permanent and Transient Networks by : M. Pietralla
Download or read book Permanent and Transient Networks written by M. Pietralla and published by Springer. This book was released on 1987 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Viscoelastic Properties of Entangled Polymers. II. The Interchain-Intrachain Entanglement Model by : S. D. Hong
Download or read book Viscoelastic Properties of Entangled Polymers. II. The Interchain-Intrachain Entanglement Model written by S. D. Hong and published by . This book was released on 1976 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our earlier model of entangled chain dynamics represented the elastic effects at entanglement points as a coupling with the surrounding medium, which was propagated weakly to every other entanglement site on the parent chain. In this way, a great variety of linear viscoelastic phenomena could be successfully predicted, with the only significant deficiency being a quantitative failure in curve-fitting the local minimum in dynamic loss modulu, G(omega). Here we introduce the 'intrachain entanglement' or the 'internal entanglement' in which the parent chain entangles directly with itself. Elastic forces between pairs of internal entanglements are assumed to be stronger than those with the medium ('external entanglements'). Predictions of the new model are compared with rheological data on monodisperse polystyrene. Good agreement was obtained between theory and experiment, including G(omega). (Author).
Book Synopsis A Kinetic Network Model for Nonlinear Viscoelastic Flow Properties of Entangled Monodisperse Polymers by : David Soong
Download or read book A Kinetic Network Model for Nonlinear Viscoelastic Flow Properties of Entangled Monodisperse Polymers written by David Soong and published by . This book was released on 1978 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, we shall propose a kinetic network model which appears to predict the observed nonlinear viscoelastic flow properties of entangled polymer systems. The basic molecular mechanism of this model attributes the rate-dependence of viscosity and normal stress difference to the decrease in entanglement density with increasing shear rate. In a flow field, entanglements are being formed and disengaged constantly. The entanglement loss process is caused primarily by the imposed shear and is assumed to be proportional to the shear rate to a power a; where a(
Book Synopsis Linear Viscoelastic Properties of Homogeneous Bulk Polymers by : David Syhlih Soong
Download or read book Linear Viscoelastic Properties of Homogeneous Bulk Polymers written by David Syhlih Soong and published by . This book was released on 1978 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mechanical Properties of Very High Molecular Weight Polyisobutylene by : Marcia E. Weidknecht
Download or read book Mechanical Properties of Very High Molecular Weight Polyisobutylene written by Marcia E. Weidknecht and published by . This book was released on 2014 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: The viscoelastic properties of elastomers have been well documented in the literature and continue to be investigated. New molecular theories and new experimental methods have both complicated and elucidated the mechanisms and phenomena of viscoelastic behavior. In both the processing and the use of elastomers, the ability to predict and to control the behavior is important if not crucial to the economical and efficient use of materials. Polyisobutylene has unique properties. It is an elastomer at room temperature but it is highly damping and it is has much higher impermeability to gasses than other elastomers. There was a unique opportunity to obtain a quantity of very high molecular weight polyisobutylene. The fractionation of a bulk polymer can yield different molecular weight and molecular weight distribution fractions according to the solubility of the size of the molecules. By fractionating a polymer, narrower molecular weight distribution samples can be isolated with presumably the same chemical properties. The investigation of entanglements and disentanglements in networks of permanent and transient networks is one area of viscoelasticity that is both interesting and practical. In this work a very high molecular weight polyisobutylene material was fractionated and characterized. Some thermal and physical properties were investigated with the intent of looking at the disentanglement of an uncrosslinked material that behaves in some ways as if it is crosslinked. All of the fractionated samples were well above the entanglement molecular weight of polyisobutylene, yet the low molecular weight fractions exhibited flow under tensile, dynamic, and stress relaxation tests. The very high molecular weight fractions and the bulk polymer behaved much more like chemically crosslinked networks in the same tests.
Book Synopsis Modeling of Rheological Properties for Entangled Polymer Systems by : Nilanjana Banerjee
Download or read book Modeling of Rheological Properties for Entangled Polymer Systems written by Nilanjana Banerjee and published by . This book was released on 2016 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The study of entangled polymer rheology both in the field of medicine and polymer processing has their major importance. Mechanical properties of biomolecules are studied in order to better understand cellular behavior. Similarly, industrial processing of polymers needs thorough understanding of rheology so as to improve process techniques. Work in this dissertation has been organized into three major sections. Firstly, numerical/analytical models are reviewed for describing rheological properties and mechanical behaviors of cytoskeleton. The cytoskeleton models are classified into categories according to the length scales of the phenomena of interest. The main principles and characteristics of each model are summarized and discussed by comparison with each other, thus providing a systematic understanding of biopolymer network modeling. Secondly, a new constitutive "toy" Mead-Banerjee-Park (MBP) model is developed for monodisperse entangled polymer systems, by introducing the idea of a configuration dependent friction coefficient (CDFC) and entanglement dynamics (ED) into the MLD "toy" model. The model is tested against experimental data in steady and transient extensional and shear flows. The model simultaneously captures the monotonic thinning of the extensional flow curve of polystyrene (PS) melts and the extension hardening found in PS solutions. Thirdly, the monodisperse MBP model is accordingly modified into polydisperse MBP "toy" constitutive model to predict the nonlinear viscoelastic material properties of model polydisperse systems. The polydisperse MBP toy model accurately predicts the material properties in the forward direction for transient uniaxial extension and transient shear flow"--Abstract, page iv.
Book Synopsis Dynamics of Associative Polymer Networks by : Irina Mahmad Rasid
Download or read book Dynamics of Associative Polymer Networks written by Irina Mahmad Rasid and published by . This book was released on 2021 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: Associative polymer networks are a versatile class of materials as demonstrated by their use in a wide variety of applications including biomaterials, viscosity modifiers and underwater adhesives. The viscoelastic and transport properties displayed by these associative networks can be tuned by careful design of the polymers that make up the network, as well as the transient interactions between them. Thus, elucidating the relationship between the molecular level details and the observed macroscopic properties is of high importance to further advance our understanding of associative networks. However, the complex dynamics displayed by these materials over a wide range of length and time scales present a significant challenge in studying this relation. This thesis aims to provide insights into the molecular origin of the dynamics of associative polymer networks. The first part of this thesis investigates the molecular origin of shear thinning in associative networks through the design of a model associative polymer and a custom-built set-up referred to as “rheo-fluorescence” to quantify force-induced bond dissociation under shear flow. Comparison to existing models in transient network theory then demonstrate that retraction of dangling chains alone is insufficient to account for shear thinning in the model associative polymer network. Additional modes are likely contributing to the observed shear thinning behavior. The second part of this thesis focuses on the effect of sticker density, sticker clustering and entanglements on the dynamics of the associative networks through combined studies of self-diffusion performed using forced Rayleigh scattering (FRS) and rheology. All three studies were performed using well-defined polymers with the same chemical composition such that the observed effects are solely due to the changes in sticker density, clustering and entanglements introduced during synthesis. The combined FRS and rheology studies on the effect of sticker density using a set of random copolymers revealed apparent superdiffusive scaling for chains with up to 15 stickers. This finding demonstrates that molecular hopping and thus, deviation from predictions of mean-field models persists to a higher limit than expected. To study the effect of sticker clustering, a polymer with clustered stickers was synthesized such that the molecular weight and sticker density were comparable to the random copolymers. It is demonstrated that the network topology is significantly altered by sticker clustering as evidenced by the opposite trends observed in the FRS and rheology measurements. Finally, the onset of entanglements was examined by performing FRS and rheology measurements on a high molecular polymer, prepared at concentrations that span the unentangled to the weakly entangled regime. A clear transition seen in the self-diffusion measurements demonstrates the advantage of FRS to study the transition regimes where other techniques like rheology only show subtle changes.
Book Synopsis Viscoelastic Properties of Polymers by : John D. Ferry
Download or read book Viscoelastic Properties of Polymers written by John D. Ferry and published by John Wiley & Sons. This book was released on 1980-09-16 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt: Viscoelastic behavior reflects the combined viscous and elastic responses, under mechanical stress, of materials which are intermediate between liquids and solids in character. Polymers the basic materials of the rubber and plastic industries and important to the textile, petroleum, automobile, paper, and pharmaceutical industries as well exhibit viscoelasticity to a pronounced degree. Their viscoelastic properties determine the mechanical performance of the final products of these industries, and also the success of processing methods at intermediate stages of production. Viscoelastic Properties of Polymers examines, in detail, the effects of the many variables on which the basic viscoelastic properties depend. These include temperature, pressure, and time; polymer chemical composition, molecular weight and weight distribution, branching and crystallinity; dilution with solvents or plasticizers; and mixture with other materials to form composite systems. With guidance by molecular theory, the dependence of viscoelastic properties on these variables can be simplified by introducing certain ancillary concepts such as the fractional free volume, the monomeric friction coefficient, and the spacing between entanglement loci, to provide a qualitative understanding and in many cases a quantitative prediction of how to achieve desired results. The phenomenological theory of viscoelasticity which permits interrelation of the results of different types of experiments is presented first, with many useful approximation procedures for calculations given. A wide variety of experimental methods is then described, with critical evaluation of their applicability to polymeric materials of different consistencies and in different regions of the time scale (or, for oscillating deformations, the frequency scale). A review of the present state of molecular theory follows, so that viscoelasticity can be related to the motions of flexible polymer molecules and their entanglements and network junctions. The dependence of viscoestic properties on temperature and pressure, and its descriptions using reduced variables, are discussed in detail. Several chapters are then devoted to the dependence of viscoelastic properties on chemical composition, molecular weight, presence of diluents, and other features, for several characteristic classes of polymer materials. Finally, a few examples are given to illustrate the many potential applications of these principles to practical problems in the processing and use of rubbers, plastics, and fibers, and in the control of vibration and noise. The third edition has been brought up to date to reflect the important developments, in a decade of exceptionally active research, which have led to a wider use of polymers, and a wider recognition of the importance and range of application of viscoelastic properties. Additional data have been incorporated, and the book s chapters on dilute solutions, theory of undiluted polymers, plateau and terminal zones, cross-linked polymers, and concentrated solutions have been extensively rewritten to take into account new theories and new experimental results. Technical managers and research workers in the wide range of industries in which polymers play an important role will find that the book provides basic information for practical applications, and graduate students in chemistry and engineering will find, in its illustrations with real data and real numbers, an accessible introduction to the principles of viscoelasticity.
Book Synopsis Viscoelastic Properties of Homogeneous Block Copolymers and Entangled Monodisperse Homopolymers by : David Syhlih Soong
Download or read book Viscoelastic Properties of Homogeneous Block Copolymers and Entangled Monodisperse Homopolymers written by David Syhlih Soong and published by . This book was released on 1977 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1979 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
