The Effect Of Temperature On The Transport Properties Of High Performance Polymers
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The Effect Of Temperature On The Transport Properties Of High Performance Polymers
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Author : Kevin Anthony Stevens
language : en
Publisher:
Release Date : 2016
The Effect Of Temperature On The Transport Properties Of High Performance Polymers written by Kevin Anthony Stevens and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
The transport properties of high-performance polymers are typically studied near ambient conditions. However, many separations are performed at temperatures either above or below ambient conditions. The permeability and solubility of light gases in thermally rearranged (TR) polymers were measured as a function of temperature. Solubilities decreased with increasing temperature for all samples. At low TR conversion, the sorption process initially becomes less exothermic. However, enthalpies of sorption do not significantly change with TR conversion after thermal rearrangement. Permeabilities increase with increasing temperature for all but CO2 at the highest TR conversion. As extent of thermal rearrangement increases, activation energies increase slightly before decreasing significantly at higher TR conversions. Activation energies of diffusion decreased with increasing TR conversion while enthalpies of sorption remained mostly constant. At the highest TR conversion, decreases in temperature move the polymer toward the upper right on the upper bound. Polybenzimidazoles have been the focus of increasing amounts of study due to their good H2/CO2 separation properties and high thermal stability. Gas transport properties of a novel series of polybenzimidazoles based on a new tetraaminodiphenylsulfone (TADPS) monomer have been characterized at temperatures from 35 to 190 °C. Permeability increases with increasing temperature for all gases. Separations with TADPS-based PBIs are strongly size selective, with CO2/N2, CO2/CH4, and N2/CH4 selectivities decreasing with increasing temperature. However, H2/CO2 selectivities increase with increasing temperature due to a lower activation energy of permeation for CO2 than for H2.
The Thermal Transport Properties Of Polymers
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Author : David Hands
language : en
Publisher:
Release Date : 1976
The Thermal Transport Properties Of Polymers written by David Hands and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1976 with categories.
The theories of thermal transport in polymers, which are mainly qualitative, are reviewed. The behaviour of amorphous polymers is better understood than that of partially crystalline ones. An apparatus for measuring the thermal conductivity of solid and molten polymers from room temperature to 250 degrees C is described. 'Edge effects' are eliminated by enclosing the heat source and samples inside the heat sink; hence guard rings are not used. The heat flow is three dimensional and the conductivity is obtained by a numerical calculation. Two disc shaped samples 48mm diameter and 2mm thick are required. An apparatus for measuring the thermal diffusivity of solid and molten polymers from room temperature to 250 degrees C is also described. Disc samples the same size as for the conductivity apparatus are used and the heat equation is again solved numerically. Conductivity and diffusivity results are reported for high density polyethylene, polypropylene, three grades of polymethyl methacrylate, three grades of polystyrene, and a series of carbon black filled natural rubber compounds. To show the effect of molecular weight, conductivity results for a range of polyethylene glycols and a range of silicone fluids are also presented.
Transport Properties Of Polymeric Membranes
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Author : Sabu Thomas
language : en
Publisher: Elsevier
Release Date : 2017-11-20
Transport Properties Of Polymeric Membranes written by Sabu Thomas and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-11-20 with Science categories.
Transport Properties of Polymeric Membranes is an edited collection of papers that covers, in depth, many of the recent technical research accomplishments in transport characteristics through polymers and their applications. Using the transport through polymer membranes method leads to high separation efficiency, low running costs, and simple operating procedures compared to conventional separation methods. This book provides grounding in fundamentals and applications to give you all the information you need on using this method. This book discusses the different types of polymer, their blends, composites, nanocomposites and their applications in the field of liquid, gas and vapor transport. Some topics of note include modern trends and applications of polymer nanocomposites in solvent, vapor and gas transport; fundamentals and measurement techniques for gas and vapor transport in polymers; and transport properties of hydrogels. This handpicked selection of topics, and the combined expertise of contributors from global industry, academia, government and private research organizations, make this book an outstanding reference for anyone involved in the field of polymer membranes. Presents current trends in the field of transport of liquid, gas and vapor through various polymeric systems Features case studies focused on industrial applications of membrane technology, along with fundamentals of transport and materials Helps readers quickly look up a particular technique to learn key points, capabilities and drawbacks
High Performance Polymers Polyimides Based
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Author : Marc Abadie
language : en
Publisher: BoD – Books on Demand
Release Date : 2012-12-19
High Performance Polymers Polyimides Based written by Marc Abadie and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-19 with Science categories.
The feature of polyimides and other heterocyclic polymers are now well-established and used for long term temperature durability in the range of 250 - 350'C. This book will review synthesis, mechanisms, ultimate properties, physico-chemical properties, processing and applications of such high performance materials needed in advanced technologies. It presents interdisciplinary papers on the state of knowledge of each topic under consideration through a combination of overviews and original unpublished research. The volume contains eleven chapters divided into three sections: Chemistry; Chemical and Physical Properties; and Applications.
The Role Of Channel Land Architecture Diffusion Media Transport Properties And Aging Effects On Water Transport And Storage In Polymer Electrolyte Fuel Cells
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Author : Jacob M. LaManna
language : en
Publisher:
Release Date : 2014
The Role Of Channel Land Architecture Diffusion Media Transport Properties And Aging Effects On Water Transport And Storage In Polymer Electrolyte Fuel Cells written by Jacob M. LaManna and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Electrodes categories.
Thermally driven transport of water vapor in polymer electrolyte fuel cells, also known as the heat-pipe effect or phase-change-induced flow, can transport several times the generated amount of water given enough temperature differentials. Understanding this transport process is necessary to properly engineer the water balance in the fuel cell to ensure high performance and long operational life. Channel-land architecture, diffusion media heat and mass transport properties, and operational age can all have an influence on thermally driven flow. High resolution neutron imaging was used to determine the steady-state water accumulation in various cell configurations to understand the influence of these parameters. A novel non-dimensional parameter was proposed to predict the influence of engineering parameters on water balance. The thermal transport number (TTN) compares the strength of anode and cathode thermally driven flow to determine a bias for transport to the anode. Channel-land architecture, specifically asymmetric flow field patterns with larger anode lands, was found to pump water to the anode and allow for large accumulations of water with saturation approaching 60%. Water transport was facilitated to the anode by a delta-T inversion caused by the insulating effect of the cathode gas channel located opposite of the center of the large anode land. To limit anode water accumulation, a new experimental high diffusion resistance anode diffusion media was evaluated. This material was found to be effective at reducing anode water accumulation primarily due to the increased tortuosity of the material but also due to the higher thermal conductivity reducing the thermal transport effect. Material age was shown to reduce cell water content due to increased hydrophilic nature and increased thermal conductivity that increased from inlet to outlet with greater effects on the anode. A parametric study was performed to determine what parameters have the strongest influence on thermally driven transport. It was found that porosity and tortuosity of the diffusion media, and channel-land architecture can be engineered to drive water balance in a favorable direction. Temperature and thermal conductivity primarily influence the strength of thermal transport. This work demonstrated methods to properly design thermal management for optimized and predictive water transport.
High Temperature Properties And Applications Of Polymeric Materials
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Author : Martin R. Tant
language : en
Publisher:
Release Date : 1995
High Temperature Properties And Applications Of Polymeric Materials written by Martin R. Tant and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Science categories.
Presents information on the synthesis, processing, and characterization of polymers and polymer composites for high performance materials needing to withstand high temperatures. Discusses the synthesis and properties of new thermally stable polymers. Includes new approaches for modeling material processing and decomposition. Provides a broad perspective by examining the science and engineering aspects of polymeric materials for high-temperature applications.
Electrochemical Studies In Cyclic Esters
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Author : William Sidney Harris
language : en
Publisher:
Release Date : 1958
Electrochemical Studies In Cyclic Esters written by William Sidney Harris and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1958 with Electrochemical analysis categories.
Approximations For The Thermodynamic And Transport Properties Of High Temperature Air
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Author : C. Frederick Hansen
language : en
Publisher:
Release Date : 1958
Approximations For The Thermodynamic And Transport Properties Of High Temperature Air written by C. Frederick Hansen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1958 with Air categories.
The thermodynamic and transport prorerties of high-temperature air are found in closed form starting from approximate partition functions for the major components in air and neglecting all minor components. The compressibility, energy, entropy, the specific heats, the speed of sound, the coefficients of viscosity and of thermal conductivity, and the Prandtl numbers for air are tabulated from 500 degrees to 15,000 degrees K over a range of pressure from 0.0001 to 100 atmospheres. The enthalpy of air and the mol fractions of the major components of air can easily be found from the tabulated values for compressibility and energy. It is predicted that the Prandtl number for fully ionized air will become small compared to unity, the order of 0.01, and this implies that boundary layers in such flow will be very transparent to heat flux.
A New Method For Measuring The Thermal Transport Properties Of Polymers In The Solid State Range Of Temperatures
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Author : Mohammed Anis
language : en
Publisher:
Release Date : 1967
A New Method For Measuring The Thermal Transport Properties Of Polymers In The Solid State Range Of Temperatures written by Mohammed Anis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1967 with Polymerization categories.
Study Of Transport Properties And Structure Of Extended Chian Polymers
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Author : R. Edward Barker
language : en
Publisher:
Release Date : 1985
Study Of Transport Properties And Structure Of Extended Chian Polymers written by R. Edward Barker and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with categories.