Download or read book Mechanical Properties of Model Polymer Glasses written by Kenji Yoshimoto and published by . This book was released on 2005 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanical Properties of Polymer Glasses written by Luca Conca and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This manuscript presents recent extensions to the PFVD model, based on the heterogeneity of theh dynamics of glassy polymers at the scale of a few nanometers et solved by 3D numerical simulation, which aim at providing a unified physical description of the mechanical and dynamical properties of glassy polymers during plastic deformation. Three main topics are treated: Plasticization. Under applied deformation, polymers undergo yield at strains of a few percent and stresses of some 10 MPa.We propose that the elastic energy stored at the scale of dynamical heterogeneities accelerates local dynamics. We observe yield stresses of a few 10 MPa are obtained at a few percent of deformation and that plastification is due to a relatively small amount of local yields. It has been observed that dynamics becomes faster and more homogeneous close to yield and that the average mobility attains a stationary value, linear with the strain rate. We propose that stress-induced acceleration of the dynamics enhances the diffusion of monomers from slow domains to fast ones (facilitation mechanism), accelerating local dynamics. This allows for obtaining the homogeneisation of the dynamics, with the same features observed during experiments. Strain-hardening, in highly entangled and cross-linked polymers. At large strain, stress increases with increasing strain, with a characteristic slope (hardening modulus) of order 10 - 100 MPa well below the glass transition. Analogously to a recent theory, we propose that local deformation orients monomers in the drawing direction and slows dows the dynamics, as a consequence of the intensification of local interactions. The hardening moduli mesured, the effect of reticulation and of strain rate are comparable with experimental data. In addition, strain-hardening is found to have a stabilizing effect over strain localization and shear banding.

Download or read book Polymer Glasses written by Connie B. Roth and published by CRC Press. This book was released on 2016-12-12 with total page 573 pages. Available in PDF, EPUB and Kindle. Book excerpt: "the present book will be of great value for both newcomers to the field and mature active researchers by serving as a coherent and timely introduction to some of the modern approaches, ideas, results, emerging understanding, and many open questions in this fascinating field of polymer glasses, supercooled liquids, and thin films" –Kenneth S. Schweizer, Morris Professor of Materials Science & Engineering, University of Illinois at Urbana-Champaign (from the Foreword) This book provides a timely and comprehensive overview of molecular level insights into polymer glasses in confined geometries and under deformation. Polymer glasses have become ubiquitous to our daily life, from the polycarbonate eyeglass lenses on the end of our nose to large acrylic glass panes holding water in aquarium tanks, with advantages over glass in that they are lightweight and easy to manufacture, while remaining transparent and rigid. The contents include an introduction to the field, as well as state of the art investigations. Chapters delve into studies of commonalities across different types of glass formers (polymers, small molecules, colloids, and granular materials), which have enabled microscopic and molecular level frameworks to be developed. The authors show how glass formers are modeled across different systems, thereby leading to treatments for polymer glasses with first-principle based approaches and molecular level detail. Readers across disciplines will benefit from this topical overview summarizing the key areas of polymer glasses, alongside an introduction to the main principles and approaches.

Download or read book The Physics of Glassy Polymers written by R. N. Haward and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 635 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work sets out to provide an up-to-date account of the physical properties and structure of polymers in the glassy state. Properties measured above the glass transition temperature are therefore included only in so far as is necessary for the treatment of the glass transition process. This approach to the subject therefore excludes any detailed account of rubber elasticity or melt rheology or of the structure and conformation of the long chain molecule in solution, although knowledge derived from this field is assumed where required. Major emphasis is placed on structural and mechanical properties, although a number of other physical properties are included. Naturally the different authors contributing to the book write mainly from their own particular points of view and where there are several widely accepted theoretical approaches to a subject, these are sometimes provided in different chapters which will necessarily overlap to a significant extent. For example, the main theoretical presentation on the subject of glass transition is given in Chapter 1. This is supplemented by accounts of the free volume theory in Chapter 3 and in the Introduction, and a short account of the work of Gibbs and DiMarzio, also in Chapter 3. Similarly, there is material on solvent cracking in Chapters 7 and 9, though the two workers approach the subject from opposite directions. Every effort has therefore been made to encourage cross-referencing between different chapters.

Download or read book Mechanical Properties and Testing of Polymers written by G.M. Swallowe and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume represents a continuation of the Polymer Science and Technology series edited by Dr. D. M. Brewis and Professor D. Briggs. The theme of the series is the production of a number of stand alone volumes on various areas of polymer science and technology. Each volume contains short articles by a variety of expert contributors outlining a particular topic and these articles are extensively cross referenced. References to related topics included in the volume are indicated by bold text in the articles, the bold text being the title of the relevant article. At the end of each article there is a list of bibliographic references where interested readers can obtain further detailed information on the subject of the article. This volume was produced at the invitation of Derek Brewis who asked me to edit a text which concentrated on the mechanical properties of polymers. There are already many excellent books on the mechanical properties of polymers, and a somewhat lesser number of volumes dealing with methods of carrying out mechanical tests on polymers. Some of these books are listed in Appendix 1. In this volume I have attempted to cover basic mechanical properties and test methods as well as the theory of polymer mechanical deformation and hope that the reader will find the approach useful.

Download or read book An Introduction to the Mechanical Properties of Solid Polymers written by I. M. Ward and published by John Wiley & Sons. This book was released on 2005-08-19 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a comprehensive introduction to the mechanical behaviour of solid polymers. Extensively revised and updated throughout, the second edition now includes new material on mechanical relaxations and anisotropy, composites modelling, non-linear viscoelasticity, yield behaviour and fracture of tough polymers. The accessible approach of the book has been retained with each chapter designed to be self contained and the theory and applications of the subject carefully introduced where appropriate. The latest developments in the field are included alongside worked examples, mathematical appendices and an extensive reference. Fully revised and updated throughout to include all the latest developments in the field Worked examples at the end of the chapter An invaluable resource for students of materials science, chemistry, physics or engineering studying polymer science

Download or read book Understand the Mechanical Behaviors of Polymer Glasses Under Extension and Compression written by Jianning Liu and published by . This book was released on 2018 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: "It is of great fundamental important and practical interest to understand what controls the mechanical properties of polymeric glasses, such as shear yielding, necking, crazing, strain hardening and the brittle-ductile transition. Despite the tremendous efforts in the past decades to explorer the mechanical instabilities of polymer glasses, many topics about the nature of glass transition, nature of stress remain vague and under extensive debates. In this dissertation, we carried out a series of mechanical tests to study the mechanical response of polymeric glasses in both uniaxial extension and compression. Based on our recent phenomenological molecular model, this work investigates the origin of mechanical stress based on stress relaxation and brittle-ductile transition experiments of polymer glasses. Different from previous models emphasizing the inter-segmental contribution in stress, our stress relaxation experimental results revealed the important role of chain network by intra-chain connectivity and chain uncrossability. In Capture III, in room temperature stress relaxation experiments, we studied the stress relaxation behaviors of four different commercial polymer glasses under both extension and compression large ductile deformation over a wide range of rate. It was found that the initial stress relaxation rate after holding post-yield deformation is linearly proportional to the rate of prior deformation. While the pre-yield stress relaxation is logarithmically slow. This rate rescaling behaviors indicates the surviving segmental mobility in absence of ongoing deformation was due to the yield induced activation process. In Capture IV, to elucidate the nature of stress during deformation and stress relaxation, temperature for stress relaxation was increased to near Tg. All the pre-yield stress would vanish within fast segmental relaxation time independent of rate, while the initial post-yield stress relaxation can be either faster or far slower than the segmental dynamics dependents on prior deformation rate. Residual stress after large post-yield relaxation was observed to retain significant levels on the time scale much longer than the time scale for all the rate range investigated near Tg. Supporting results by MD simulation shown the chain network is essential in the mechanical response of uniaxial compression of glassy polymers through the chain network's lateral resistance to the lateral expansion and contribute to compressive stress. In Capture V and VI, to understand the role of chain network under uniaxial compression, we systematically studied how the structural change of chain network dictates whether the uniaxial compression of polymer glasses is ductile or suffers brittle fracture. Those structural characteristics of the perceived chain network can be changed by variation of molecular weight, molecular composition, and anisotropic reconstruction through melt stretching"--Website of ETD."

Download or read book Atomistic Modeling of Mechanical Properties of Polymeric Glasses written by Doros Nicolas Theodorou and published by . This book was released on 1985* with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Segmental Dynamics of Polymer Glasses During Deformation written by Trevor Bennin and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A probe reorientation technique is used to measure changes in the segmental dynamics of polymer glasses during and after deformation. In this thesis, experiments are performed on poly(lactic acid) (PLA) and lightly crosslinked poly(methyl methacrylate) (PMMA) glasses in which fluorescent probe molecules, N,N'-dipentyl-3,4,9,10-perylenedicarboximide (DPPC), are dispersed. Glasses are subject to constant strain rate deformation and cyclic loading/unloading using a custom-built deformation apparatus that allows for concurrent fluorescence detection. The work described in this thesis provides quantitative dynamics and mechanical data that can test existing models and theories that describe the nonlinear deformation of polymer glasses. This is expected to improve predictions of the mechanical properties of polymer glasses and expand the utility of these materials in engineering applications. The segmental dynamics of PLA glasses between Tg - 15 K and Tg - 25 K are monitored during uniaxial extension at constant strain rates from 6x10^(-6) to 3x10^(-5) s-1. Segmental relaxation times are decreased by up to a factor of 30 in the plastic flow regime relative to the undeformed state. In the plastic flow regime, the segmental relaxation time is related to the local strain rate via a power law. Additionally, is it observed that the segmental dynamics become more homogeneous during deformation. Comparisons to previous probe reorientation experiments on lightly crosslinked PMMA and various models of polymer glass deformation are discussed. The effects of cyclic loading/unloading on the segmental dynamics and mechanical properties of lightly crosslinked PMMA glasses between Tg - 10 K and Tg - 25 K are investigated. Sets of 5000 tensile loading/unloading cycles are performed, with cycle extension strains ranging from 0.003 to 0.007. After cycling, segmental dynamics either remained unchanged or were faster relative to an undeformed sample. Surprisingly, the mechanical properties were unchanged after cycling under all investigated conditions. No evidence of overaging was observed in the optical or mechanical measurements as a result of these cyclic loading/unloading experiments; comparison of the results to various simulations and experiments are discussed.

Download or read book Mechanical Properties of Polymers written by Norbert M. Bikales and published by . This book was released on 1971 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanical Properties of Solid Polymers written by Ian M. Ward and published by John Wiley & Sons. This book was released on 2012-10-22 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing an updated and comprehensive account of the propertiesof solid polymers, the book covers all aspects of mechanicalbehaviour. This includes finite elastic behavior, linearviscoelasticity and mechanical relaxations, mechanical anisotropy,non-linear viscoelasicity, yield behavior and fracture. New to thisedition is coverage of polymer nanocomposites, and molecularinterpretations of yield, e.g. Bowden, Young, and Argon. The book begins by focusing on the structure of polymers,including their chemical composition and physical structure. It goes on to discuss the mechanical properties and behaviour ofpolymers, the statistical molecular theories of the rubber-likestate and describes aspects of linear viscoelastic behaviour, itsmeasurement, and experimental studies. Later chapters cover composites and experimental behaviour,relaxation transitions, stress and yielding. The book concludeswith a discussion of breaking phenomena.

Download or read book Molecular Mechanics of Glassy and Semicrystalline Polymers written by Masoud Razavi and published by . This book was released on 2020 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers are a unique class of modern materials. Despite their light mass density, their mechanical properties are strong enough for a variety of applications either through crystallization or vitrification to achieve sufficient rigidity. However, high Young's modulus is not the only necessary characteristic. Desirably, polymeric materials should be ductile, for example, tolerating considerable bending. In this regard polymers (at room temperature) can be classified as brittle or ductile polymers. A ductile or brittle polymer structurally, can be either amorphous or semicrystalline. Moreover, a polymeric material (either glassy or semicrystalline) could remain ductile at temperatures much lower than its glass transition temperature (Tg). Ductile polymers include semicrystalline polymers such as polyethylene (PE) and polypropylene (PP) with low Tg, and polyamide with high Tg, as well as some amorphous glassy polymers such as bisphenol A polycarbonate (bpA-PC) and polyethylene terephthalate (PET). Examples of the brittle polymers under ambient conditions, are semicrystalline polymers with high Tg such as semicrystalline PET or Poly(lactic acid) (PLA), or glassy amorphous polymers such as polystyrene (PS) and poly(methyl methacrylate) (PMMA). For decades mechanical behavior of polymers is an important research topic in polymer science and despite the tremendous researches in this filed, there is no comprehensive molecular picture that can universally describe the mechanical behavior of polymeric materials at the molecular level. Consequently, previous studies are not able to propose a method to efficiently improve the mechanical properties of polymers without additives, e.g. turning a brittle polymer to a ductile one.This dissertation consists of two parts: PART A is about the molecular mechanics of glassy amorphous polymers, and PART B focuses on the molecular mechanics of semicrystalline polymers. In each part, we carried out three independent projects to address several important questions in the mechanics of polymer glasses and semicrystalline polymers. Influenced by our recent phenomenological molecular model, this work comprehensively emphasizes on the important role of the chain networking, arising from intra-chain connectivity and chain uncrossability, on affording ductility into the polymeric materials.Chapter I is a general introduction into the PART A. In Chapter II we study several different polymer glasses in tensile, creep and stress relaxation mechanical experiments in order to understand the crazing behavior of polymer glasses. Based on our inclusive experiments and counterintuitive results, an alternative molecular mechanism and model is proposed to explain craze initiation in polymer glasses. This chapter also includes a refrainment to our recent phenomenological molecular model. Chapter III studies the two-phase rubber-toughened polymer glasses. It is indicated that the commercial rubber-toughened polymer glasses do not undergo molecular level yielding characterized by the increased segmental mobility, thus we title the strain softening point of these materials as apparent yield point. Methods to switch the mechanism of yielding from apparent to the real one is also proposed. A novel rubber-toughening mechanism that is operative in the recently synthesized nano-rubber-toughened PMMA by Dow chemicals, is suggested. In Chapter IV, real-time birefringence measurements during different mechanical experiments of PMMA and PS is performed in order to achieve molecular level insights into the deformation of polymer glasses. For the first time, birefringence changes at the post-yield deformation of PS and PMMA are measured. Attempts are made to explain the molecular reasons of the birefringence changes and its correlation/decorrelation with stress, during different mechanical experiments including uniaxial tensile, creep and stress relaxation experiments.By an analogy with PART A, PART B of dissertation, starts with a general introduction into the molecular mechanics of semicrystalline polymers in Chapter V. In Chapter VI, our general framework and universal molecular picture of the deformation of semicrystalline polymers are introduced. Chapter VII investigates the molecular mechanics of semicrystalline PLA which is an ideal model semicrystalline polymer, through a comparative study with the mechanics of its amorphous state. Reasons behind mechanical weakness of this polymer and in general any other semicrystalline polymer below Tg, and lower drawability above Tg, are explained in light of the results from time-resolved polarized optical microscope (POM) observations during large deformation of semicrystalline PLA. After identifying the origins of the brittle response of semicrystalline polymers, a universal strategy is proposed in Chapter VIII to turn brittle semicrystalline polymers to ductile. Finally, Chapter IX summarizes the overall body of the dissertation and offers main conclusions.

Download or read book Mechanical Properties of Solid Polymers written by I. M. Ward and published by . This book was released on 1983-06-27 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: A concise, self-contained introduction to solid polymers, the mechanics of their behavior and molecular and structural interpretations. This updated edition provides extended coverage of recent developments in rubber elasticity, relaxation transitions, non-linear viscoelastic behavior, anisotropic mechanical behavior, yield behavior of polymers, breaking phenomena, and other fields.

Download or read book Mechanical and Viscoelastic Properties of Glass forming Polymers in the Bulk and Thin Films written by Ivan Kriuchevskyi and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on the equilibrium shear modulus Geq of well-known glass-forming polymer model system (sampled by means of MD), we have addressed the general question of how the mechanical properties of the thin polymer films differs from the bulk. Using ”stress fluctuation” formalism we obtained Geq(T) for the bulk and films. It has been demonstrated that in both cases Geq unambiguously separates the fluid state (Geq = 0) from the glass (Geq > 0). We also stressed that Geq for the film does not only depend on film thickness h, but also on tangential pressure that is a consequence of the film preparation procedure.

Download or read book Mechanical Properties of Polymers written by Lawrence E. Nielsen and published by . This book was released on 1962 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure and Properties of Glassy Polymers written by Martin R. Tant and published by . This book was released on 1998 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt: In twenty-nine chapters by leading authorities, Structure and Properties of Glassy Polymers provides readers with comprehensive coverage of basic and applied research on glass polymers as well as a wealth of information on current topics such as molecular modeling, characterization, polymer glasses in confined spaces, and conducting glass polymers. The characterization techniques presented include temperature-modulated differential scanning calorimetry, dielectric loss spectroscopy, photochemical hole burning, positron annihilation lifetime spectroscopy, and transient current generation.

Download or read book Molecular Mobility in Deforming Polymer Glasses written by Nikhil Padhye and published by Springer Nature. This book was released on 2021-10-15 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book bridges disparate fields in an exploration of the phenomena and applications surrounding molecular mobility in glassy materials experiencing inelastic deformation. The subjects of plastic deformation and polymer motion/interdiffusion currently belong to the two different fields of continuum mechanics and polymer physics, respectively. However, molecular motion associated with plastic deformation is a key ingredient to gain fundamental understanding, both at the macroscopic and microscopic level. This short monograph provides necessary background in the aforementioned fields before addressing the topic of molecular mobility accompanied by macroscopic inelastic deformation in an accessible and easy-to-understand manner. A new phenomenon of solid-state deformation-induced bonding in polymers is discussed in detail, along with some broad implications in several manufacturing sectors. Open questions pertaining to mechanisms, mechanics, and modeling of deformation-induced bonding in polymers are presented. The book’s clear language and careful explanations will speak to readers of diverse backgrounds.