Download or read book Mass and Charge Transport in Hydrated Polymeric Membranes written by Marshall T. McDonnell and published by . This book was released on 2016 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mass and charge transport through hydrated polymer membranes has significant importance for many areas of engineering and industry. Multi-scale modeling and simulation techniques were used to study transport in relation to two specific membrane applications: (1) food packaging and (2) additives for polymer electrolytes. Chitosan/chitin films were studied due to their use as a sustainable, biodegradable food packaging film. The effects of hydration on the solvation, diffusivity, solubility, and permeability of oxygen molecules in these films were studied via molecular dynamics and confined random walk simulations. With increasing hydration, the membrane was observed to have a more homogeneous water distribution with the polymer chains being fully solvated. Insight from this work will help guide molecular modeling of chitosan/chitin membranes and experimental synthesis of these membranes, specifically highlighting efforts to chemically tailor chitosan membranes to favor discrete as opposed to continuous aqueous domains to help reduce oxygen permeability. Additives for proton exchange membranes (PEMs) were studied to aid in the developing next-generation membrane materials for fuel cell applications. We calculate and present predictions of our analytical model that describes the fundamental relationship between the nanoscale structure of PEMs and their proton conductivity using a set of structural descriptors, accounting for nanopore size, functionalization and connectivity in order to predict proton conductivities in PEMs. The model reproduces experimentally determined conductivities in two current PEM materials. To extend the model based on structural descriptors of PEMs, we studied polyethylene glycol (PEG), a polymer used in electrochemistry applications due to it hydrophilicity and pH-dependent behavior in aqueous environments. We conducted ab initio molecular dynamics simulations of an excess proton in bulk water and aqueous triethylene glycol (TEG) solution and reactive molecular dynamics simulations of an excess proton in bulk water, aqueous TEG solution, and aqueous PEG solution. We determined differences in protonic defect structures, kinetics, thermodynamics, and hydrogen-bond networks associated with structural diffusion between systems. Driving forces for polymeric membrane design goals include economics, efficiency, energy consumption and sustainable production. Insight from this work hopes to aid in determining key design parameters and reduce time-to-discovery for developing next-generation polymeric membranes.

Download or read book Electrochemically Induced Charge and Mass Transport in Polypyrrole Poly styrene Sulfonate Molecular Composites written by and published by . This book was released on 1991 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polypyrrole/poly(styrene sulfonate) (PP/PSS) molecular composites have been synthesized by the electrochemical polymerization of pyrrole in the presence of sodium poly(styrene sulfonate) (PSS-Na+). Their synthesis and charge transport properties have been investigated by a combination of electrochemical and gravimetric techniques using the Electrochemical Quartz Crystal Microbalance (EQCM). Electropolymerization in water at 0.8 V vs. Ag/AgC1 yields a partially hydrated polymer complex with sulfonate dopant anions from the PSS. Mass transport is found to be cation specific, as expected for a composite system, with the polyelectrolyte chains physically entrapped within the polymer membrane. Frequency responses of the EQCM during electrochemical switching are found to increase with increasing electrolyte cation mass as Li+is equivalent to Na+

Download or read book Characterization of Self Assembly and Charge Transport in Model Polymer Electrolyte Membranes written by Keith Morgan Beers and published by . This book was released on 2012 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is broad interest in creating polymer electrolyte membranes (PEMs) that have a charged hydrophilic nanophase, where the size and geometry of the phase can be precisely controlled. The applications for such materials range from portable power generating devices to water purification. There is a need to better characterize the self-assembly, thermodynamics, and performance of both current and future PEMs. To this end a series of chapters is presented, that explore the development of techniques, equipment, methods, and materials to enable further progress in the field. The interaction of PEMs with external ionic solutions can be used to determine fundamental thermodynamic properties of the ions that reside within the membrane itself. Traditional techniques used to probe ions in PEMs, such as conductivity, can be greatly enhanced by knowing the number of dissociated ions and their activity coefficients. A technique is presented that provides one of the first methods able to quantify such properties in PEMs. The ionic species in PEMs are believed to reside in nanoscale ionic aggregates. Only recently have researchers begun to focus on the properties of this aggregation in regards to PEM performance. A summary of this phenomenon, as well as speculation on its effect on transport and thermodynamic properties is presented. In addition, evidence that suggests block copolymers offer a method of inhibiting aggregate formation is discussed. Characterization of PEM morphology is critical to properly understand structure-function relationships. Due to a lack of proper equipment, the morphological characterization of PEMs has been mostly limited to the dry state. The design and operation of a novel sample stage, used to simultaneously measure morphology and conductivity in humid air as a function of temperature and relative humidity is presented. Precise control over humidity and accurate determination of morphology and conductivity over a wide range of temperatures is shown. At present there is an incomplete understanding of the thermodynamic interaction between PEMs and water of varying activity. The morphology, water uptake, and proton conductivity of sulfonated polystyrene-block-polyethylene (PSS-PE) was studied under controlled relative humidity (RH) and in liquid water. Extrapolation of the domain size, water uptake, and conductivity in humid vapor to RH = 100% allowed for an accurate comparison between the properties of PSS-PE hydrated in saturated vapor and in liquid water. Absent from this system was Schroeder's Paradox, which expects the properties in saturated water vapor to be less than those obtained in liquid water. Polymers that are semi-crystalline are ubiquitous as commercial polymers because of their mechanical properties. Little is known about the effects of polymer crystallization on PEM structure and performance. The model system, PSS-PE, was synthesized at a variety of molecular weights to probe how crystallization affects performance for a variety of conducting domain sizes. Results are shown that indicate crystallization disrupts the self-assembly of low molecular weight PEMs, resulting in poor water uptake and proton conductivity in small domains. Increasing domain size results in less morphological disruption, leading to an improvement in performance at larger domain sizes. This work improves upon the ability of researchers to characterize and understand the relationship between the structure and performance of PEMs. The findings presented herein provide further understanding toward the goal of rational design of nanostructured membranes that show improved conductivity in a variety of conditions.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel Cell Technology written by Nigel Sammes and published by Springer Science & Business Media. This book was released on 2006-05-14 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel cells are a very promising technology for the clean and efficient production of power. Fuel Cell Technology is an up-to-date survey of the development of this technology and will be bought by researchers and graduate students in materials control and chemical engineering working at universities and institutions and researchers and technical managers in commercial companies working in fuel cell technology.

Download or read book Dynamics of Soft Matter written by VICTORIA GARCIA SAKAI and published by Springer Science & Business Media. This book was released on 2011-12-19 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamics of Soft Matter: Neutron Applications provides an overview of neutron scattering techniques that measure temporal and spatial correlations simultaneously, at the microscopic and/or mesoscopic scale. These techniques offer answers to new questions arising at the interface of physics, chemistry, and biology. Knowledge of the dynamics at these levels is crucial to understanding the soft matter field, which includes colloids, polymers, membranes, biological macromolecules, foams, emulsions towards biological & biomimetic systems, and phenomena involving wetting, friction, adhesion, or microfluidics. Emphasizing the complementarities of scattering techniques with other spectroscopic ones, this volume also highlights the potential gain in combining techniques such as rheology, NMR, light scattering, dielectric spectroscopy, as well as synchrotron radiation experiments. Key areas covered include polymer science, biological materials, complex fluids and surface science.

Download or read book Introduction to Membrane Science and Technology written by Heinrich Strathmann and published by John Wiley & Sons. This book was released on 2011-10-17 with total page 515 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by a dedicated lecturer and leading membrane scientist, who has worked both in academia and industry, this advanced textbook provides an impressive overview of all aspects of membranes and their applications. Together with numerous industrial case studies, practical examples and questions, the book provides an excellent and comprehensive introduction to the topic. Advanced students as well as process and chemical engineers working in industry will profit from this resource. A significant feature of the book is the treatment of more recently developed membranes and their applications in energy conversion, biomedical components, controlled release devices and environmental engineering with an indication of the present and future commercial impact. The solutions to the questions in the book can be found under http://www.wiley-vch.de/publish/en/books/ISBN3-537-32451-8/ From the Contents: * Introduction * Fundamentals * Membrane Preparation and Characterization * Principles of Membrane Separation Processes * Membrane Modules and Concentration Polarization * Membrane Process Design and Operation

Download or read book Dynamic Aspects of Crystallization and Mass Transport in Polymers and Polymeric Membranes for Pharmaceutical Use written by Neil Cameron Beaton and published by . This book was released on 1975 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamic Aspects of Crystallization and Mass Transport in Polymers and Polymeric Membranes for Pharmaceutical Use written by Neil Cameron Beaton and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Encyclopedia of Electrochemical Power Sources written by Jürgen Garche and published by Newnes. This book was released on 2013-05-20 with total page 4532 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Encyclopedia of Electrochemical Power Sources is a truly interdisciplinary reference for those working with batteries, fuel cells, electrolyzers, supercapacitors, and photo-electrochemical cells. With a focus on the environmental and economic impact of electrochemical power sources, this five-volume work consolidates coverage of the field and serves as an entry point to the literature for professionals and students alike. Covers the main types of power sources, including their operating principles, systems, materials, and applications Serves as a primary source of information for electrochemists, materials scientists, energy technologists, and engineers Incorporates nearly 350 articles, with timely coverage of such topics as environmental and sustainability considerations

Download or read book Introduction to Transfer Phenomena in PEM Fuel Cells written by Bilal Abderezzak and published by Elsevier. This book was released on 2018-11-13 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Transfer Phenomena in PEM Fuel Cells presents the fruit of several years of research in the area of fuel cells. The book illustrates the transfer phenomena occurring inside a single cell and describes the technology field of hydrogen, explicitly the production, storage and risk management of hydrogen as an energy carrier. Several applications of hydrogen are also cited, and special interest is dedicated to the PEM Fuel Cell. Mass, charge and heat transfer phenomena are also discussed in this great resource that includes explanations, illustrations and governing equations for each section. Illustrates transfer phenomena occurring within a single cell Describes the technological field of hydrogen (production, storage, and risk and management) Introduces the various applications of hydrogen Presents mass transfer, charge and heat phenomena

Download or read book Diffusion of Electrolytes in Polymers written by Gennadiĭ Efremovich Zaikov and published by VSP. This book was released on 1988-12 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diffusion is the process of transport of a substance in space due to thermal migration of 'kinetic' particles. This book firstly determines the general aspects of diffusion in polymers and goes onto to explore characteristics of electrolyte diffusion in different polymers, acids; water diffusion and chemical reactions.

Download or read book The Characterization of Mass and Charge Transport Development of a Model Membrane written by John Leonard Anderson and published by . This book was released on 1971 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rigorous Modeling and Experimental Validation of Mass Charge and Energy Transport in a DMFC Polymer Electrolyte Membrane written by Thorsten Schultz and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Modeling of Interfacial Proton Transport in Polymer Electrolyte Membranes written by Swati Bhalchandra Vartak and published by . This book was released on 2014 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proton conductivity of polymer electrolyte membranes (PEMs) plays a crucial role for the performance of polymer electrolyte fuel cells (PEFCs). High hydration of Nafion-like membranes is crucial to high proton conduction across the PEM, which limits the operation temperature of PEFCs to 100o C. At elevated temperatures (100o C) and minimal hydration, interfacial proton transport becomes vital for membrane operation. Along with fuel cell systems, interfacial proton conduction is of utmost importance in biology and materials science; yet experimental findings of ultrafast proton transport at densely packed arrays of anionic surface groups have remained controversial and unexplained. In the main part of this thesis work, ab initio simulations were performed on a minimally hydrated, densely packed array of sulfonic acid surface groups (SGs). This system served as a model to study the mechanism of interfacial proton transport in perfluorosulfonic acid membranes. Specifically, simulations were performed to explore the impact of the density of SGs on the mechanism of interfacial proton transport. Results reveal a mechanism of highly collective proton motion at a critical SG separation of 6.6 Å. The activation free energy of proton translocations exhibits a high sensitivity to the SG density. A spontaneous concerted proton transition was observed with low activation barrier at a surface group separation of 6.8 Å. When protons translocate concertedly, the activation barrier of the transition drops by more than a factor of two to the value of 0.25 eV compared to the case of disconcerted proton transfer. Results show that the hydrogen-bond network with long-range order that forms upon densification of SGs at the interface enables highly effective proton transport under minimal hydration conditions. These results were then incorporated in a soliton theory for describing collective proton transport through minimally hydrated and highly charged interfaces.

Download or read book Ion Exchange Membrane Separation Processes written by H Strathmann and published by Elsevier. This book was released on 2004-01-29 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today, membranes and membrane processes are used as efficient tools for the separation of liquid mixtures or gases in the chemical and biomedical industry, in water desalination and wastewater purification. Despite the fact that various membrane processes, like reverse osmosis, are described in great detail in a number of books, processes involving ion-exchange membranes are only described in a fragmented way in scientific journals and patents; even though large industrial applications, like electrodialysis, have been around for over half a century. Therefore, this book is emphasizing on the most relevant aspects of ion-exchange membranes. This book provides a comprehensive overview of ion-exchange membrane separation processes covering the fundamentals as well as recent developments of the different products and processes and their applications. The audience for this book is heterogeneous, as it includes plant managers and process engineers as well as research scientists and graduate students. The separate chapters are based on different topics. The first chapter describes the relevant Electromembrane processes in a general overview. The second chapter explains thermodynamic and physicochemical fundamentals. The third chapter gives information about ion-exchange membrane preparation techniques, while the fourth and fifth chapter discusses the processes as unit operations giving examples for the design of specific plants. First work on the principles and applications of electrodialysis and related separation processes Presently no other comprehensive work that can serve as both reference work and text book is available Book is suited for teaching students and as source for detailed information

Download or read book PEM Fuel Cells written by Gurbinder Kaur and published by Elsevier. This book was released on 2021-11-16 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: PEM Fuel Cells: Fundamentals, Advanced Technologies, and Practical Application provides a comprehensive introduction to the principles of PEM fuel cell, their working condition and application, and the latest breakthroughs and challenges for fuel cell technology. Each chapter follows a systematic and consistent structure with clear illustrations and diagrams for easy understanding. The opening chapters address the basics of PEM technology; stacking and membrane electrode assembly for PEM, degradation mechanisms of electrocatalysts, platinum dissolution and redeposition, carbon-support corrosion, bipolar plates and carbon nanotubes for the PEM, and gas diffusion layers. Thermodynamics, operating conditions, and electrochemistry address fuel cell efficiency and the fundamental workings of the PEM. Instruments and techniques for testing and diagnosis are then presented alongside practical tests. Dedicated chapters explain how to use MATLAB and COMSOL to conduct simulation and modeling of catalysts, gas diffusion layers, assembly, and membrane. Degradation and failure modes are discussed in detail, providing strategies and protocols for mitigation. High-temperature PEMs are also examined, as are the fundamentals of EIS. Critically, the environmental impact and life cycle of the production and storage of hydrogen are addressed, as are the risk and durability issues of PEMFC technology. Dedicated chapters are presented on the economics and commercialization of PEMFCs, including discussion of installation costs, initial capital costs, and the regulatory frameworks; apart from this, there is a separate chapter on their application to the automotive industry. Finally, future challenges and applications are considered. PEM Fuel Cells: Fundamentals, Advanced Technologies, and Practical Application provides an in-depth and comprehensive reference on every aspect of PEM fuel cells fundamentals, ideal for researchers, graduates, and students. Presents the fundamentals of PEM fuel cell technology, electrolytes, membranes, modeling, conductivity, recent trends, and future applications Addresses commercialization, public policy, and the environmental impacts of PEMFC in dedicated chapters Presents state-of-the-art PEMFC research alongside the underlying concepts