Polymer Dynamics and Relaxation

  • Filename: polymer-dynamics-and-relaxation.
  • ISBN: 9781107320253
  • Release Date: 2007-09-13
  • Number of pages:
  • Author: Richard Boyd
  • Publisher: Cambridge University Press

Polymers exhibit a range of physical characteristics, from rubber-like elasticity to the glassy state. These particular properties are controlled at the molecular level by the mobility of the structural constituents. Remarkable changes in mobility can be witnessed with temperature, over narrow, well defined regions, termed relaxation processes. This is an important, unique phenomenon controlling polymer transition behaviour and is described here at an introductory level. The important types of relaxation processes from amorphous to crystalline polymers and polymeric miscible blends are covered, in conjunction with the broad spectrum of experimental methods used to study them. In-depth discussion of molecular level interpretation, including atomistic level computer simulations and applications to molecular mechanism elucidation, are discussed. The result is a self-contained approach to polymeric interpretation suitable for researchers in materials science, physics and chemistry interested in the relaxation processes of polymeric systems.

Polymer Dynamics as a Mechanism of Cartilage Flow independent Viscoelasticity

  • Filename: polymer-dynamics-as-a-mechanism-of-cartilage-flow-independent-viscoelasticity.
  • ISBN: 9780549493785
  • Release Date: 2007
  • Number of pages: 218
  • Author:
  • Publisher: ProQuest

Articular cartilage is the soft tissue consisting mostly of extracellular matrix biopolymers and water that covers the ends of bones in synovial joints. Cartilage functions mechanically: it provides low-friction surfaces for articulation and deforms during joint contact to decrease contact pressure and increase joint stability. As such, understanding the specific molecular origins of cartilage resistance to deformation is necessary to understand cartilage mechanical function.

Relaxation Dynamics of Branched Polymers

  • Filename: relaxation-dynamics-of-branched-polymers.
  • ISBN: 9780549431039
  • Release Date: 2007
  • Number of pages: 127
  • Author:
  • Publisher: ProQuest

The tube dilation model for star and comb polymers was investigated in detail and predictions compared to rheological data from polypropylene, polybutadiene and polystyrene comb polymers along with PEP star polymers. The relaxation time from the Tube Dilation Model was compared with the classical Tube Model and was shown to have an extra power dependence on the fraction of the comb backbone.

The Mesoscopic Theory of Polymer Dynamics

  • Filename: the-mesoscopic-theory-of-polymer-dynamics.
  • ISBN: 9048122317
  • Release Date: 2009-12-16
  • Number of pages: 256
  • Author: Vladimir N. Pokrovskii
  • Publisher: Springer Science & Business Media

The theory presented in this book explains in a consistent manner all dynamics effects observed in very concentrated solutions and melts of linear polymers from a macromolecular point of view. The presentation is compact and self-contained.

Polymer Dynamics in Dilute Media

  • Filename: polymer-dynamics-in-dilute-media.
  • ISBN: STANFORD:hj553gv4999
  • Release Date: 2011
  • Number of pages:
  • Author:
  • Publisher: Stanford University

Polymers undergo a sharp coil to stretch conformational transition in extension dominated flows when the strain rate exceeds a critical value. Dramatic change in flow behavior is known to occur at the coil-stretch transition, making it useful for several commercial applications. Despite decades of study, this phenomenon remains surrounded with controversy as the effect of solvent properties and fluid flow elements on this transition is not fully understood. In this work, we present a study of the coil-stretch transition and related hysteresis phenomenon using stochastic computer simulations. We first investigate the effect of solvent quality on the coil-stretch transition using Brownian dynamics simulations. Unlike experiments, which are plagued with problems related to polydispersity of polymers and inaccurate control over flow profiles, simulations offer a powerful platform to systematically study the effect of solvent quality while keeping all other parameters in the system constant. The system consists of a polymer subjected to planar elongational flow in both theta solvents and good solvents. The polymer is represented by a bead-spring chain model undergoing elongational flow. Solvent-mediated effects such as fluctuating hydrodynamic interactions (HI) and excluded volume (EV) are included rigorously. Conformational hysteresis is understood in terms of a 1-D energy landscape theory with an activation energy barrier for transition. At steady state, depending upon the flow rate, the energy landscape can either have one or two energy wells. An energy landscape with one well corresponds to the coiled state at low flow rate and stretched state at high flowrate. The double welled landscape corresponds to the hysteretic regime where both coiled and stretched conformational states coexist across the ensemble population. A key factor in determining the effect of solvent quality is the use of a proper measure of solvent quality. In almost all earlier studies, the effect of molecular weight on solvent quality has been neglected, producing inconsistent results. Here, the solvent quality is quantified carefully such that the effect of molecular weight and temperature is taken into account. Contrary to earlier findings, it is observed that with improvement in solvent quality, the chains unravel faster and the critical strain rate at which the coil to stretch transition takes place decreases. Furthermore, the solvent quality has a profound effect on the scaling of the critical strain rate with molecular weight and on both the transient and steady state properties of the system. Universal functions are shown to exist for the observed dynamic and static properties, which will prove useful in determining the operating parameters for experiments. In particular, the ratio of the two different relaxation times (longest relaxation time and zero shear rate viscosity) is found to be a universal function of solvent quality independent of molecular weight. The relaxation times (both the longest relaxation time and the zero shear rate viscosity) increase while the critical strain rate is found to decrease with solvent quality. Next, the study of conformational hysteresis is extended to more complicated 3-D flows to understand the effect of flow vorticity on this phenomenon. Heretofore, there has been no systematic methodology for studying the dynamical interactions between polymer molecules and elementary flow patterns in three-dimensional flows. Such a framework is essential not just for gaining valuable insights into the physics of complex fluids at a fundamental level, but it is also crucial for various important applications like turbulent drag reduction where the underlying physical mechanisms involve dynamical interactions between polymers and turbulence fine scale flow features. Such a study is presented here to provide a framework to interpret complex fluid phenomenon in terms of elementary flow patterns. We investigate the conformational

The Theory of Polymer Dynamics

  • Filename: the-theory-of-polymer-dynamics.
  • ISBN: 0198520336
  • Release Date: 1988
  • Number of pages: 391
  • Author: Masao Doi
  • Publisher: Oxford University Press

'This book is destined to join the classics of polymer science...an essential purchase for any serious student of polymer dynamics.' British Polymer Journal

Relaxation in Polymers

  • Filename: relaxation-in-polymers.
  • ISBN: 9810213735
  • Release Date: 1993
  • Number of pages: 329
  • Author: Takayoshi Kobayashi
  • Publisher: World Scientific

Conjugated polymers are attractive from the viewpoint of possible applications as novel nonlinear optical materials and conductive materials. They are also very important as a group of materials of one dimensionality. The progress of research in this field is very rapid. At the present stage it is extremely useful to have review articles giving information on the most recent progress.Relaxation in Polymers contains state-of-the-art reviews on: ultrafast responses in various conjugated polymers with large optical nonlinearity; ultrafast relaxation in polysilanes; electronic properties of polysilanes; fast transient photoconductivity studies of polyacetylene and polydiacetylene; evolution of photoexcitations in polyacetylene and related polymers from femtoseconds to milliseconds; photoexcited states in conjugated polymers, optical properties of halogen-bridged mixed-valent metal complexes and dynamics of soliton pairs in polyacetylene.

Broadband Dielectric Spectroscopy

  • Filename: broadband-dielectric-spectroscopy.
  • ISBN: 9783642561207
  • Release Date: 2012-12-06
  • Number of pages: 729
  • Author: Friedrich Kremer
  • Publisher: Springer Science & Business Media

Both an introductory course to broadband dielectric spectroscopy and a monograph describing recent dielectric contributions to current topics, this book is the first to cover the topic and has been hotly awaited by the scientific community.

Molecular dynamics and relaxation phenomena in glasses

  • Filename: molecular-dynamics-and-relaxation-phenomena-in-glasses.
  • ISBN: UOM:39015021545028
  • Release Date: 1987
  • Number of pages: 218
  • Author: Thomas Dorfm├╝ller
  • Publisher: Not Avail

This book presents the proceedings of a workshop on glass-forming liquids held at the University of Bielefeld in 1985. The aim of the meeting was to seek unifying interpretations which may apply to all glass-forming materials like inorganic and polymer glasses. Also, new data was presented and modern interpretations were applied which represent the state-of-the-art knowledge about the unusual physical properties of these chemically-diverse glass-forming materials. The book should be of interest to specialists in the subject, to polymer scientists, glass technologists and materials scientists, but also - and most importantly - to researchers and teachers who wish to become informed on some of the most recent fundamental research in the fields.

Polymer and Cell Dynamics

  • Filename: polymer-and-cell-dynamics.
  • ISBN: 3764369248
  • Release Date: 2003-08-25
  • Number of pages: 290
  • Author: Wolfgang Alt
  • Publisher: Springer Science & Business Media

Polymer and cell dynamics play an important role in processes like tumor growth, metastasis, embryogenesis, immune reactions and regeneration. Based on an international workshop on numerical simulations of polymer and cell dynamics in Bad Honnef (Germany) in 2000, this volume provides an overview of the relevant mathematical and numerical methods, their applications and limits. Polymer and Cell Dynamics will be of interest to scientists and advanced undergraduates.

Effects of Nanoscale Confinement and Interfaces on the Structural Relaxation of Amorphous Polymers Monitored at the Molecular Scale by Fluorescence and Dielectric Spectroscopy

  • Filename: effects-of-nanoscale-confinement-and-interfaces-on-the-structural-relaxation-of-amorphous-polymers-monitored-at-the-molecular-scale-by-fluorescence-and-dielectric-spectroscopy.
  • ISBN: 9780549507734
  • Release Date: 2008
  • Number of pages: 249
  • Author:
  • Publisher: ProQuest

In summary, this work investigated confinement and interfacial effects on the relaxation dynamics of polymer at the glass transition (T g), above the glass transition (alpha-relaxation dynamics), and below the glass transition (physical aging).

Electrical Properties of Polymers

  • Filename: electrical-properties-of-polymers.
  • ISBN: 1420030477
  • Release Date: 2004-05-21
  • Number of pages: 600
  • Author: Evaristo Riande
  • Publisher: CRC Press

Electrical Properties of Polymers describes the electric phenomena responsible for determining the chemical and supramolecular structure of polymers and polymeric materials. The authors explore the properties of quasi-static dipoles, reviewing Brownian motion, Debye theory, Langevin and Smoluchowski equations, and the Onsager model. This reference displays Maxwell and entropy equations, along with several others, that depict the thermodynamics of dielectric relaxation. Featuring end-of-chapter problems and useful appendices, the book reviews molecular dynamics simulations of dynamic dielectric properties and inspects mean-square dipole moments of gases, liquids, polymers, and fixed conformations.

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