Download or read book Physical Aging of Glassy Polymers in Confined Environments written by Thomas Matthew Murphy and published by . This book was released on 2012 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research project investigated the physical aging of glassy polymers in confined environments. Many recent studies of aging in glassy polymers have observed that aging behavior is often strongly affected by confinement. Understanding aging in confined environments (e.g., thin polymer films and nanocomposites) is vital for predicting long-term performance in applications that use confined glassy polymers, such as gas separation membranes and advanced nanocomposite materials. Aging in bulk and layered films produced via layer-multiplying co-extrusion was studied using gas permeability measurement and differential scanning calorimetry (DSC). The layered films consisted of polysulfone (PSF) and a rubbery co-layering material, with PSF layers ranging in thickness from ~185 nm to ~400 nm. Gas permeation aging studies at 35 °C revealed that the PSF layers in layered films aged in a manner that was similar to bulk PSF and independent of layer thickness. This finding differs from what was observed previously in freestanding PSF films, in which aging depended strongly on thickness and was accelerated relative to bulk. Isothermal aging studies at 170 °C and cooling rate studies were performed on both bulk and layered samples using DSC. The aging of the PSF layers was similar to aging in bulk PSF for films having PSF layer thicknesses of ~640 nm and ~260 nm, while the film with 185 nm PSF layers showed a slightly higher aging rate than that of bulk PSF. The results of the DSC studies generally support the conclusions of our gas permeation aging studies. The absence of strong thickness dependence in aging studies of layered films tends to support the idea that the effect of film thickness on physical aging stems from interfacial characteristics and not merely thickness per se. The physical aging of thin polystyrene (PS) films at 35 °C was also investigated using gas permeation techniques. PS films of 400 nm and 800 nm did not exhibit aging behavior that was highly accelerated relative to bulk or strongly dependent on film thickness. At the thicknesses and aging temperature considered, the aging of PS shows much weaker thickness dependence than that seen in polymers like PSF and Matrimid.
Download or read book Structure Relaxation and Physical Aging of Glassy Polymers written by and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of Thermal Analysis and Calorimetry written by and published by Elsevier. This book was released on 2018-03-12 with total page 862 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Thermal Analysis and Calorimetry: Recent Advances, Techniques and Applications, Volume Six, Second Edition, presents the latest in a series that has been well received by the thermal analysis and calorimetry community. This volume covers recent advances in techniques and applications that complement the earlier volumes. There has been tremendous progress in the field in recent years, and this book puts together the most high-impact topics selected for their popularity by new editors Sergey Vyazovkin, Nobuyoshi Koga and Christoph Schick—all editors of Thermochimica Acta. Among the important new techniques covered are biomass conversion; sustainable polymers; polymer nanocompsoties; nonmetallic glasses; phase change materials; propellants and explosives; applications to pharmaceuticals; processes in ceramics, metals, and alloys; ionic liquids; fast-scanning calorimetry, and more. Features 19 all-new chapters to bring readers up to date on the current status of the field Provides a broad overview of recent progress in the most popular techniques and applications Includes chapters authored by a recognized leader in each field and compiled by a new team of editors, each with at least 20 years of experience in the field of thermal analysis and calorimetry Enables applications across a wide range of modern materials, including polymers, metals, alloys, ceramics, energetics and pharmaceutics Overviews the current status of the field and summarizes recent progress in the most popular techniques and applications
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 587 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 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 Aspects of Physical Aging and Solid State Processing of Polymeric Glasses written by Angel Cugini and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on unconventional methods to improve the mechanical properties of glassy polymers such as PMMA, TritanTM Copolyester, and epoxy-based thermosets by influencing the intrinsic mechanical behavior through solid-state processing. The solid-state processing includes pre-stress, mechanical rejuvenation, and mechanical work hardening that cause changes in microscopic conformation structure and dynamics of glassy polymers and enhance properties such as non-linear deformation behavior and low and high velocity fracture. To utilize such unconventional techniques, one needs to understand fundamental origins of dynamics in polymeric glasses where the chain segments are not completely frozen and the segmental diffusion displays high degree of intermolecular cooperativity. We demonstrate how fundamental principles of polymer physics can be applied to improve fracture toughness of polymeric glasses. Emphasis is placed on structure-process-property relationships of these systems. In Chapter 2 long-term effects of physical aging and solid state processing are monitored through dynamic mechanical properties of an amorphous glassy polymer. These phenomena are investigated through dynamic mechanical testing that evaluates in-situ the evolution of the storage modulus with time during annealing and physical aging. Comparisons are made on samples with different thermal histories and mechanical treatment. The results are discussed in context to an aging rate obtained from the various thermal and mechanical treatments. We demonstrate that there is apparent work hardening of glassy polymers. The effect of strain rate, dwell time and material are compared and the permanence of the processing is investigated. In Chapter 3, we investigate the effect mechanical rejuvenation on the fracture toughness of epoxy-based thermosets and correlate the kinetics of the recovery of fracture toughness to compression based ductility parameters and dynamic mechanical analysis (DMA)-based aging rates. We also investigate the effect of molecular additives, antiplasticizers, on the structural recovery rate of the epoxy after mechanical rejuvenation. Chapter 4 studies the optimization of prestressed poly (methyl methacrylate) (PMMA), through equibiaxial compression with increasing amounts of shear and simple shear. To suppress inherent large radial crack growth associated with simple shear prestress, orientation is superimposed to minimize crack growth. These prestressed states are compared at both low velocity and ballistic rates. To investigate the low velocity impact dependence on rate, a strain energy density term is used to remove the dependence of geometry. Lastly, to reduce scatter in ballistic date, a master curve is developed to collapse all data regardless of boundary conditions, rate of impact and materials. In Chapter 5 we examine the correlation between ductility parameters based on dynamic mechanical data and fracture toughness and other non-linear mechanical properties. This chapter focuses on the model system poly (methyl methacrylate) and the relationship of these ductility parameters to other engineering properties for a range of temperatures and strain rates.
Download or read book Beggar My Neighbour written by E. D. Gerard and published by . This book was released on 1882 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fast Scanning Calorimetry written by Christoph Schick and published by Springer. This book was released on 2016-06-28 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past decades, the scan rate range of calorimeters has been extended tremendously at the high end, from approximately 10 up to 10 000 000 °C/s and more. The combination of various calorimeters and the newly-developed Fast Scanning Calorimeters (FSC) now span 11 orders of magnitude, by which many processes can be mimicked according to the time scale(s) of chemical and physical transitions occurring during cooling, heating and isothermal stays in case heat is exchanged. This not only opens new areas of research on polymers, metals, pharmaceuticals and all kinds of substances with respect to glass transition, crystallization and melting phenomena, it also enables in-depth study of metastability and reorganization of samples on an 1 to 1000 ng scale. In addition, FSC will become a crucial tool for understanding and optimization of processing methods at high speeds like injection molding. The book resembles the state-of-the art in Thermal Analysis & Calorimetry and is an excellent starting point for both experts and newcomers in the field.
Download or read book Structure and Dynamics of Confined Polymers written by John J. Kasianowicz and published by Springer Science & Business Media. This book was released on 2002-07-31 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers are essential to biology because they can have enough stable degrees of freedom to store the molecular code of heredity and to express the sequences needed to manufacture new molecules. Through these they perform or control virtually every function in life. Although some biopolymers are created and spend their entire career in the relatively large free space inside cells or organelles, many biopolymers must migrate through a narrow passageway to get to their targeted destination. This suggests the questions: How does confining a polymer affect its behavior and function? What does that tell us about the interactions between the monomers that comprise the polymer and the molecules that confine it? Can we design and build devices that mimic the functions of these nanoscale systems? The NATO Advanced Research Workshop brought together for four days in Bikal, Hungary over forty experts in experimental and theoretical biophysics, molecular biology, biophysical chemistry, and biochemistry interested in these questions. Their papers collected in this book provide insight on biological processes involving confinement and form a basis for new biotechnological applications using polymers. In his paper Edmund DiMarzio asks: What is so special about polymers? Why are polymers so prevalent in living things? The chemist says the reason is that a protein made of N amino acids can have any of 20 different kinds at each position along the chain, resulting in 20 N different polymers, and that the complexity of life lies in this variety.
Download or read book The Physics of Deformation and Fracture of Polymers written by A. S. Argon and published by Cambridge University Press. This book was released on 2013-03-07 with total page 535 pages. Available in PDF, EPUB and Kindle. Book excerpt: A physical, mechanism-based presentation of the plasticity and fracture of polymers, covering industrial scale applications through to nanoscale biofluidic devices.
Download or read book The Effects of Molecular Orientation on the Physical Aging Behavior of Oriented Glassy Amorphous Polymers written by Marcus David Shelby and published by . This book was released on 1996 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Non equilibrium Phenomena in Confined Soft Matter written by Simone Napolitano and published by Springer. This book was released on 2015-08-28 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with those properties of non-equilibrium soft matter that deviate greatly from the bulk properties as a result of nanoscale confinement.The ultimate physical origin of these confinement effects is not yet fully understood. At the state of the art, the discussion on confinement effects focuses on equilibrium properties, finite size effects and interfacial interactions. However this is a limited vision which does not fully capture the peculiar behaviour of soft matter under confinement and some exotic phenomena that are displayed. This volume will be organized in the following three main themes. Equilibration and physical aging: treating non-equilibrium via the formal methodology of statistical physics in bulk, we analyse physical origin of the non-equilibrium character of thin polymer. We then focus on the impact of nanoconfinement on the equilibration of glasses of soft matter (a process of tremendous technological interest, commonly known as physical aging), comparing the latest trends of polymers in experiments, simulations with those of low-molecular weight glass formers. Irreversible adsorption: the formation of stable adsorbed layers occurs at timescales much larger than the time necessary to equilibrate soft matter in bulk. Recent experimental evidence show a strong correlation between the behaviour of polymers under confinement and the presence of a layer irreversibly adsorbed onto the substrate. This correlation hints at the possibility to tailor the properties of ultrathin films by controlling the adsorption kinetics. The book reports physical aspects of irreversible chain adsorption, such as the dynamics, structure, morphology, and crystallization of adsorbed layers. Glass transition and material properties: this section of the book focuses on the spread of absolute values in materials properties of confined systems, when measured by different experimental and computation techniques and a new method to quantify the effects of confinement in thin films and nanocomposites independently on the investigation procedure will be presented.
Download or read book Long Term Durability of Polymeric Matrix Composites written by Kishore V. Pochiraju and published by Springer Science & Business Media. This book was released on 2011-09-25 with total page 681 pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-Term Durability of Polymeric Matrix Composites presents a comprehensive knowledge-set of matrix, fiber and interphase behavior under long-term aging conditions, theoretical modeling and experimental methods. This book covers long-term constituent behavior, predictive methodologies, experimental validation and design practice. Readers will also find a discussion of various applications, including aging air craft structures, aging civil infrastructure, in addition to engines and high temperature applications.
Download or read book A Research Agenda for Transforming Separation Science written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2019-10-30 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Separation science plays a critical role in maintaining our standard of living and quality of life. Many industrial processes and general necessities such as chemicals, medicines, clean water, safe food, and energy sources rely on chemical separations. However, the process of chemical separations is often overlooked during product development and this has led to inefficiency, unnecessary waste, and lack of consensus among chemists and engineers. A reevaluation of system design, establishment of standards, and an increased focus on the advancement of separation science are imperative in supporting increased efficiency, continued U.S. manufacturing competitiveness, and public welfare. A Research Agenda for Transforming Separation Science explores developments in the industry since the 1987 National Academies report, Separation and Purification: Critical Needs and Opportunities. Many needs stated in the original report remain today, in addition to a variety of new challenges due to improved detection limits, advances in medicine, and a recent emphasis on sustainability and environmental stewardship. This report examines emerging chemical separation technologies, relevant developments in intersecting disciplines, and gaps in existing research, and provides recommendations for the application of improved separation science technologies and processes. This research serves as a foundation for transforming separation science, which could reduce global energy use, improve human and environmental health, and advance more efficient practices in various industries.
Download or read book Fundamental Investigations of the Physical Aging and Glass Transition of Amorphous Polymers written by Donald Carter Davis and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physical Aging of Glasses written by Jacques Rault and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metallic, organic and mineral glasses evolve similarly with the time and approach an equilibrium state. This physical aging, a basic feature of the glassy state, is very important for a practical point of view. The ageing time and the conditions of glass preparation are important parameters, as temperature, stress and strain levels, which affect the mechanical properties at short and long times. The kinetics of physical aging, volume, enthalpy and mechanical properties (modulus, yield stress, creep, stress relaxation), are explained in the framework of the modified Vogel-Fulcher-Tamann (VFT) law giving the relaxation time. The model is based on the dependence of the co-operativity index (Kohlrausch exponent) n of the co-operative motions (alpha motions in polymers) on the volume. Below the glass temperature the relaxation time is function of T and of the volume. In the glass state the relaxation time depend on the time of measurement and on the ageing time. The relaxation equations are given and solved numerically in various experimental conditions a) isothermal and non isothermal ageing at constant pressure, b) varying pressure at constant temperature. The so called Tg transitions observed by dilatomery and calorimetry are predicted by the VFT relaxation equations and compared to the Deborah glass temperatures. The non exponential and non linear relaxations of the volume of glassy polymers, found by Struik, Kovacs, etc.., depend on the viscoelastic parameters of the liquid (C1 and C2) and on the expansion coefficients of the liquid and solid phases, there is no adjustable parameter. The calculated solutions of the relaxation equations are compared to the KWW functions (stretched and compressed exponentials), the stabilisation domain of glasses is defined and compared to the experimental results. The glass formers materials present the well-known volume, enthalpy and creep memory effects (Struik), the amplitude and the memory time of these effects are given as function of the thermal history of the glass. The evolution of the mechanical properties of glassy polymers are dependent on the ageing time and on the stress and strain level, the individual beta motions (and then the co-operative motions) been activated by the shear component of the stress tensor. The similar non linear evolution of volume and creep is thoroughly analysed in this model, the modified VFT law explains the dependences of the yield stress, creep compliance and stress relaxation modulus with ageing time, temperature and stress or strain rate. The mechanical properties can be described also by the ansatz KWW function; the relaxation time and the Kohlrausch exponent deduced from that function is found to vary inversely with the different parameters this is a direct consequence of the modified VFT law. It is shown that the long term creep behaviour can be predicted by the model.
Download or read book Materials Science of Membranes for Gas and Vapor Separation written by Benny Freeman and published by John Wiley & Sons. This book was released on 2006-05-12 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Materials Science of Membranes for Gas and Vapor Separation is a one-stop reference for the latest advances in membrane-based separation and technology. Put together by an international team of contributors and academia, the book focuses on the advances in both theoretical and experimental materials science and engineering, as well as progress in membrane technology. Special attention is given to comparing polymer and inorganic/organic separation and other emerging applications such as sensors. This book aims to give a balanced treatment of the subject area, allowing the reader an excellent overall perspective of new theoretical results that can be applied to advanced materials, as well as the separation of polymers. The contributions will provide a compact source of relevant and timely information and will be of interest to government, industrial and academic polymer chemists, chemical engineers and materials scientists, as well as an ideal introduction to students.
