Download or read book Gas transport properties and aging of thin and thick films made from amorphous glassy polymers written by Peter Heinz Pfromm and published by . This book was released on 1994 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physical Aging of Thin and Ultrathin Glassy Polymer Films written by Brandon William Rowe and published by . This book was released on 2010 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research effort investigated the influence of confinement on the physical aging behavior of thin and ultrathin glassy polymer membranes. Membrane permeability changes with time due to physical aging, and for reasons not completely understood, the rate of permeability change can become orders of magnitude faster in films thinner than one micron. Special experimental techniques were developed to enable the study of free standing, ultrathin glassy polymer films using gas permeability measurements. The gas transport properties and physical aging behavior of free-standing glassy polysulfone (PSF) and Matrimid® films from 18-550 nm thick are presented. Physical aging persists in glassy films approaching the length scale of individual polymer coils. The membranes exhibited significant reductions in gas permeability and increases in selectivity with aging time. Additionally, the influence of physical aging on the free volume profile in thin PSF films was investigated using variable energy positron annihilation lifetimespectroscopy (PALS). The films exhibited decreasing o-Ps lifetime during physical aging, while o-Ps intensity remained constant. The o-Ps lifetime was reduced at lower implantation energies, indicating smaller free volume elements near the film surface. Thin films aged dramatically faster than bulk PSF and the PALS results agree favorably to behavior tracked by gas permeability measurements. The physical aging behavior of ultrathin films with different previous histories was also studied. The state of these materials was modulated by various conditioning treatments. Regardless of the previous history, the nature of the aging response was consistent with the aging behavior of an untreated film that was freshly quenched from above Tg, i.e., permeability decreased and pure gas selectivity increased with aging time. However, the extent of aging-induced changes in transport properties of these materials depended strongly on previous history. The properties of these ultrathin films deviate dramatically from bulk behavior, and the nature of these deviations is consistent with enhanced mobility and reduced Tg in ultrathin films, which allows them to reach a lower free volume state more quickly than bulk material. The Struik physical aging model was extended to account for the influence of film thickness on aging, and was shown to accurately describe the experimental data.
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.
Download or read book SPE ANTEC 1997 Proceedings written by Spe and published by CRC Press. This book was released on 1997-04-22 with total page 1504 pages. Available in PDF, EPUB and Kindle. Book excerpt: First published in 1997. Routledge is an imprint of Taylor & Francis, an informa company.
Download or read book Carbon Dioxide Plasticization and Conditioning of Thin Glassy Polymer Films Monitored by Gas Permeability and Optical Methods written by Norman Randall Horn and published by . This book was released on 2012 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research project investigated physical aging and carbon dioxide plasticization behavior of glassy polymer films. Recent studies have shown that thin glassy polymer films undergo physical aging more rapidly than thick films. This suggests that thickness may also play a role in the plasticization and conditioning responses of thin glassy films in the presence of highly-sorbing penetrants such as CO2. The effect of film thickness on CO2 permeation and sorption was studied extensively through carefully defined and controlled methods that provide a basis for future study of plasticization behavior. Thin films are found to be more sensitive than thick films to CO2 exposure, undergoing more extensive and rapid plasticization at any pressure. The response of glassy polymers films to CO2 is not only dependent on thickness, but also on aging time, CO2 pressure, exposure time, and prior history. Thin films experiencing constant CO2 exposure for longer periods of time exhibit an initial large increase in CO2 permeability, which eventually reaches a maximum, followed by a significant decrease in permeability for the duration of the experiment. Thick films, in contrast, do not seem to exhibit this trend for the range of conditions explored. For a series of different polymers, the extent of plasticization response tracks with CO2 solubility. There is little data available for gas sorption in thin glassy polymer films. In this work, a novel method involving spectroscopic ellipsometry is used to obtain simultaneously the film thickness and CO2 sorption capacity for thin glassy polymer films. This allows a more comprehensive look at CO2 permeability, sorption, and diffusivity as a function of both CO2 pressure and exposure time. Like the gas permeation data, these experiments suggest that thin film sorption behavior is substantially different than that of thick film counterparts. Dynamic ellipsometry experiments show that refractive index minima, fractional free volume maxima, and CO2 diffusivity maxima correlate well with observed CO2 permeability maxima observed for thin Matrimid® films. These experiments demonstrate that plasticization and physical aging are competing processes. Aging, however, dominates over long time scales. Over time, CO2 diffusivity is most affected by these competing effects, and the evolution of CO2 diffusivity is shown to be the main contributing factor to changes in CO2 permeability at constant pressure.
Download or read book Gas Transport in Glassy Polymers written by Maria Grazia De Angelis and published by MDPI. This book was released on 2021-04-22 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue of Membranes focuses on several new aspects of fluid transport in glassy polymers, with application in relevant membrane separations such as gas purification, VOC removal and CO2 capture. In particular, the focus lies on novel experimental techniques, and detailed characterization of specific phenomena like polar and multicomponent interactions during transport. The properties of novel materials, such as mixed matrix membranes based on glassy polymers and different selective fillers, are also presented. A critical review of existing modeling approaches to describe the sorption and transport in glassy polymers suitable for membrane separations is provided, including both macroscopic and atomistic models, and relying both on the standard solution–diffusion process and on the facilitated transport mechanism.
Download or read book Permeability of Plastic Films and Coatings written by Harold Hopfenberg and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms written by Linda A. Felton and published by CRC Press. This book was released on 2016-09-19 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aqueous-based film coating has become routine in the pharmaceutical industry. This process eliminates the use of organic solvents and thus avoids economic, environmental, and toxicological issues related to residual solvents and solvent recovery. Aqueous-based coating, however, is complex and many variables may impact the final product and its performance. This fourth edition of Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms aims to provide insight into the factors and parameters that should be considered and controlled for the successful development and commercialization of a coated product. The fourth edition has been revised and expanded to reflect the most recent scientific advancements from the literature. The contributing authors explain in detail, using illustrated examples, appropriate steps to solve and ideally avoid formulation, processing, and stability problems and to achieve an optimized dosage form. Trade names and chemical names of commercially marketed coatings are used throughout the text to help familiarize the reader with the various materials available for pharmaceutical applications. This book will be a valuable resource for anyone in the pharmaceutical industry working in the area of aqueous-based film coating.
Download or read book Transport Properties of Hydrogenated Amorphous Silicon Based Thin Films written by Fuchao Wang and published by . This book was released on 1994 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Temperature dependence of gas sorption and transport properties in glassy polymers written by Lora Marlene Costello and published by . This book was released on 1994 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1994 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physical Aging of Thin Glassy Polymer Films written by Yu Huang and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polyphenylene Oxide and Modified Polyphenylene Oxide Membranes written by Geeta Chowdhury and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid-membrane material interfaces, morphologies of membrane surface and the sub-layer underneath the membrane surface, and fluid transport through the membrane governed by the above interface and morphology parameters, and driving forces involved in process operatio- all these three aspects together constitute the fundamental physico-chemical and engineering basis for the practical success of Membrane Separation Technology (MST) in all its applications. Quantitative data on the above interface and morphology parameters and applicable transport equations involving the above parameters, are needed for membrane design, specification of membranes, modules and systems, and prediction of their performance for any given separation application. Even though more than 40 years have elapsed since the emergence of the field of MST, there are very few books which deal with all the above three aspects of the subject in an integrated manner. This simply shows that the field of MST is still in its early stages of development and only a small fraction of its vast potential has been practically realized to-date. Still, what has already accomplished is extraordinary both in its scope, and in its impact, on scientific research and service to society at large.
Download or read book Anomalous Gas Transport in Glassy Polymer Films written by Thomas Wesley Goodman and published by . This book was released on 1986 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polymeric Gas Separation Membranes written by D.R. Paul and published by CRC Press. This book was released on 2018-05-04 with total page 635 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymeric Gas Separation Membranes is an outstanding reference devoted to discussing the separation of gases by membranes. An international team of contributors examines the latest findings of membrane science and practical applications and explores the complete spectrum of relevant topics from fundamentals of gas sorption and diffusion in polymers to vapor separation from air. They also compare membrane processes with other separation technologies. This essential book will be valuable to all practitioners and students in membrane science and technology.
