Download or read book Mechanisms of Gas Permeation Through Polymer Membranes Summary Technical Report September 1989 August 1991 written by and published by . This book was released on 1991 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the present study is to investigate the mechanisms of gas transport in and through polymer membranes and the dependence of these mechanisms on pressure and temperature. This information is required for the development of new, energy-efficient membrane processes for the separation of industrial gas mixtures. Such processes are based on the selective permeation of the components of gas mixtures through nonporous polymer membranes. Recent work has been focused on the permeation of gases through membranes made from glassy polymers, i.e., at temperatures below the glass transition of the polymers (Tg). Glassy polymers are very useful membrane materials for gas separations because of their high selectivity toward different gases. Gases permeate through nonporous polymer membranes by a ''solution-diffusion'' process. Consequently, in order to understand the characteristics of this process it is necessary to investigate also the mechanisms of gas solution and diffusion in glassy polymers. 23 refs., 10 figs., 4 tabs.
Download or read book Mechanisms of Gas Permeation Through Polymer Membranes Summary Technical Report September 1991 August 1992 written by and published by . This book was released on 1992 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Progress is reported in two areas: (1) Concentration-temperature superposition principle (CTSP). CTSP is a theoretical model for describing the gas solubility in glassy polymers swollen by the penetrant gas. It has been extended to describe the dependence of gas diffusivity and permeability on penetrant pressure. Further extension to diffusion of gas mixtures is being studied. (2)Solubility of gases in poly(alkyl methacrylates). Solubility of methane in poly(ethyl methacrylate) and poly(n-butyl methacrylate) was measured; the Langmuir capacity constant was found to not reflect a lower excess free volume; an equation is given for relating the constant to the glass transition temperature. Solubility of ethane in the latter polymer is affected by plasticization.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanism of Gas Permeation Through Polymer Membranes Progress Report September 1 1978 May 31 1979 written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A new, more exact derivation of the free-volume model of permeation is presented in this report. The free-volume parameters A/sub d/, B/sub d/, and .gamma. have been determined for CO/sub 2/ in polyethylene from diffusivity measurements at 20 and 35/sup 0/C and at pressures of up to 23 atm. The polyethylene was in the form of semicrystalline rods, and the measurements were made with a new type of high-pressure diffusivity apparatus operating under both isobaric and isothermal conditions. The above parameters were used in conjunction with the free-volume model to predict permeability coefficients for the transport of CO/sub 2/ through polyethylene membranes as a function of pressure. The values of the predicted permeability coefficients were found to agree to within 35% or better (on the average) with those obtained directly from permeability measurements with thin polyethylene membranes. The agreement is within the expected limits, considering the assumptions of the free-volume model and the uncertainty in the diffusivity and permeability measurements. A method of determining free-volume parameters directly from permeability measurements was developed for dilute penetrant-polymer systems. This method was used to obtain values of A/sub d/, B/sub d/, and .gamma. for CO/sub 2/, CH/sub 4/, C/sub 2/H/sub 4/, C/sub 2/H/sub 6/, and C/sub 3/H/sub 8/ in polyethylene membranes. The values of B/sub d/ and .gamma. are in about the same range, respectively, as reported for other penetrant-polymer systems. No data appear to have been published previously for A/sub d/. According to the theory, B/sub d/ is thought to be related to the minimum hole size required for the displacement of a penetrant molecule in the polymer, and should depend on both the size and shape of the molecule. This was confirmed by a linear correlation of B/sub d/ with the effective molecular diameters of the above gases; these diameters make allowance for possible orientation of anisometric molecules during diffusion.
Download or read book Mechanisms of Gas Permeation Through Polymer Membranes written by and published by . This book was released on 1990 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the present study is to investigate the mechanisms by which gases are transported in and through polymer membranes, and the dependence of these mechanisms on pressure and temperature. Recent work has been focused on the permeation of gases through membranes made from glassy polymers, i.e., at temperatures below the glass transition of the polymers (Tg). During the past report period, a new theoretical model of gas solubility in glassy polymers was developed and tested with experimental data from the literature. This model describes satisfactorily the shape of solubility isotherms over wide ranges of pressure and temperatures, and is particularly useful for penetrant gases which ranges of pressure and temperatures, and is particularly useful for penetrant gases which plasticize (swell) glassy polymers. Work also continued on the behavior of light gases in poly (alkyl methacrylates). 18 refs., 6 figs.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1993-06 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index written by and published by . This book was released on 1992 with total page 1400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cumulated Index Medicus written by and published by . This book was released on 1985 with total page 1102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Artificial Kidney Bibliography written by and published by . This book was released on 1970 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Membrane Technology and Applications written by Richard W. Baker and published by John Wiley & Sons. This book was released on 2004-05-31 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: Table of Contents Preface Acknowledgments for the first edition Acknowledgments for the second edition 1 Overview of Membrane Science and Technology 1 2 Membrane Transport Theory 15 3 Membranes and Modules 89 4 Concentration Polarization 161 5 Reverse Osmosis 191 6 Ultrafiltration 237 7 Microfiltration 275 8 Gas Separation 301 9 Pervaporation 355 10 Ion Exchange Membrane Processes - Electrodialysis 393 11 Carrier Facilitated Transport 425 12 Medical Applications of Membranes 465 13 Other Membrane Processes 491 Appendix 523 Index 535.
Download or read book Japanese Technical Abstracts written by and published by . This book was released on 1987 with total page 832 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Index Medicus written by and published by . This book was released on 2003 with total page 1924 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. for 1963- include as pt. 2 of the Jan. issue: Medical subject headings.
Download or read book PEM Water Electrolysis written by Dmitri Bessarabov and published by Academic Press. This book was released on 2018-07-23 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen Energy and Fuel Cell Primers is a series of concise books that present those coming into this broad and multidisciplinary field the most recent advances in each of its particular topics. Its volumes bring together information that has thus far been scattered in many different sources under one single title, which makes them a useful reference for industry professionals, researchers and graduate students, especially those starting in a new topic of research. These volumes, PEM Water Electrolysis vol 1 and 2, allows these readers to identify the technology gaps for the development of commercially viable PEM electrolysis systems for energy applications. This primer examines the fundamentals of PEM electrolysis and selected research topics that are currently subject of attention by academic and industry community, such as gas cross-over and AST protocols. This lays the foundation for the exploration of the current industrial trends for PEM electrolysis, such as power to gas application, are discussed, with strong focus on the current trends in the application of PEM electrolysis associated with energy storage. These include durability aspects of PEM electrolysis systems and components, accelerated stress test protocols, manufacturing aspects of large-scale electrolyzers and components, gas crossover problems in PEM electrolyzer safety, and challenges associated with high-current density operation of PEM electrolyzers. A technology development matrix for systems and components requirements will also be covered, as well as unconventional PEM water electrolysis systems, such as ozone generators Presents the fundamentals and most current knowledge in proton exchange membrane water electrolyzers Explores the technology gaps and challenges for commercial deployment of PEM water electrolysis technologies Includes unconventional systems, such as ozone generators Brings together information from many different sources under one single title, making it a useful reference for industry professionals, researchers and graduate students alike
Download or read book Polymer Permeability written by J. Comyn and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers are permeable, whilst ceramics, glasses and metals are gener ally impermeable. This may seem a disadvantage in that polymeric containers may allow loss or contamination of their contents and aggressive substances such as water will diffuse into polymeric struc tures such as adhesive joints or fibre-reinforced composites and cause weakening. However, in some cases permeability is an advantage, and one particular area where this is so is in the use of polymers in drug delivery systems. Also, without permeable polymers, we would not enjoy the wide range of dyed fabrics used in clothing and furnishing. The fundamental reason for the permeability of polymers is their relatively high level of molecular motion, a factor which also leads to their high levels of creep in comparison with ceramics, glasses and metals. The aim of this volume is to examine some timely applied aspects of polymer permeability. In the first chapter basic issues in the mathema tics of diffusion are introduced, and this is followed by two chapters where the fundamental aspects of diffusion in polymers are presented. The following chapters, then, each examine some area of applied science where permeability is a key issue. Each chapter is reasonably self-contained and intended to be informative without frequent outside reference. This inevitably leads to some repetition, but it is hoped that this is not excessive.
Download or read book Chemical Engineering Progress written by and published by . This book was released on 1974 with total page 836 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.
