scholarly journals Water transport through epoxy-based powder pipeline coatings

2021 ◽  
Author(s):  
Hossein Zargarnezhad ◽  
Edouard Asselin ◽  
Dennis Wong ◽  
C.N. Catherine Lam
Keyword(s):  
Water Transport ◽  
Powder Coating ◽  
Operating Conditions ◽  
Vapor Transport ◽  
Internal Stresses ◽  
Water Molecules ◽  
Epoxy Coatings ◽  
Water Permeation ◽  
Vapor Permeation ◽  
Self Association

Hydration of epoxy coatings reduces adhesion performance and causes degradation of the material, such as microstructural failures. Quantification of water vapor transport at elevated temperatures is fundamental to understanding polymer coating performance, especially when the coating is exposed to extreme operating conditions. As the water activity increases, the permeability/selectivity of polymers against other permeants changes. In this study, we examined the water permeation kinetics of two common epoxy-based powder coating systems for pipelines (fusion-bonded epoxy, FBE, and high-performance powder coating, HPPC) across a range of industrially-relevant temperatures (from room temperature to 80°C). Specifically, we utilized vapor permeation features of FBE and HPPC films with quantification of equilibrium flux as a function of temperature and pressure. In addition, we analyzed the nonlinear dependency of water transport on the vapor concentration at 65°C. The vapor transport analysis demonstrated that although data for FBE were indicative of a decrease in permeability around 65°C, perhaps due to self-association of water molecules, the coating was likely to experience a plasticization pressure around this temperature. We also examined microstructural changes of the epoxy network due to water transport. Our results revealed evidence of irreversible damage to epoxy coatings under wet-state conditions above 65°C. It appears that the combination of thermal exposure and internal stresses in the glassy epoxy lead to a phase separation of filler particles from the epoxy matrix, as well as to a distinctive cavity formation in the coating membrane. Yet, despite formation of percolating paths for water transport, our results indicate that vapor permeation is primarily restrained due to self-association of water molecules. The vapor transport flux and its permeance are lowered by one order of magnitude in the multilayered HPPC thanks to the moisture-resistant polyethylene topcoat, thus reducing the extent of damage to the underlying substrate. Since barrier protection against gas phase diffusion is controlled by the FBE primer, however, consequences of coating hydration are more pronounced in the overall selectivity toward gaseous transport. Hydrothermal exposure is likely to increase aggregate porosity of the coating and a conservative implementation of standard coating requirements is therefore reasonable to avoid early degradation issues.

scholarly journals Water transport through epoxy-based powder pipeline coatings

2021 ◽  
Author(s):  
Hossein Zargarnezhad ◽  
Edouard Asselin ◽  
Dennis Wong ◽  
C.N. Catherine Lam
Keyword(s):  
Water Transport ◽  
Powder Coating ◽  
Operating Conditions ◽  
Vapor Transport ◽  
Internal Stresses ◽  
Water Molecules ◽  
Epoxy Coatings ◽  
Water Permeation ◽  
Vapor Permeation ◽  
Self Association

Hydration of epoxy coatings reduces adhesion performance and causes degradation of the material, such as microstructural failures. Quantification of water vapor transport at elevated temperatures is fundamental to understanding polymer coating performance, especially when the coating is exposed to extreme operating conditions. As the water activity increases, the permeability/selectivity of polymers against other permeants changes. In this study, we examined the water permeation kinetics of two common epoxy-based powder coating systems for pipelines (fusion-bonded epoxy, FBE, and high-performance powder coating, HPPC) across a range of industrially-relevant temperatures (from room temperature to 80°C). Specifically, we utilized vapor permeation features of FBE and HPPC films with quantification of equilibrium flux as a function of temperature and pressure. In addition, we analyzed the nonlinear dependency of water transport on the vapor concentration at 65°C. The vapor transport analysis demonstrated that although data for FBE were indicative of a decrease in permeability around 65°C, perhaps due to self-association of water molecules, the coating was likely to experience a plasticization pressure around this temperature. We also examined microstructural changes of the epoxy network due to water transport. Our results revealed evidence of irreversible damage to epoxy coatings under wet-state conditions above 65°C. It appears that the combination of thermal exposure and internal stresses in the glassy epoxy lead to a phase separation of filler particles from the epoxy matrix, as well as to a distinctive cavity formation in the coating membrane. Yet, despite formation of percolating paths for water transport, our results indicate that vapor permeation is primarily restrained due to self-association of water molecules. The vapor transport flux and its permeance are lowered by one order of magnitude in the multilayered HPPC thanks to the moisture-resistant polyethylene topcoat, thus reducing the extent of damage to the underlying substrate. Since barrier protection against gas phase diffusion is controlled by the FBE primer, however, consequences of coating hydration are more pronounced in the overall selectivity toward gaseous transport. Hydrothermal exposure is likely to increase aggregate porosity of the coating and a conservative implementation of standard coating requirements is therefore reasonable to avoid early degradation issues.

scholarly journals Water transport through epoxy-based powder pipeline coatings

2021 ◽  
Author(s):  
Hossein Zargarnezhad ◽  
Edouard Asselin ◽  
Dennis Wong ◽  
C.N. Catherine Lam
Keyword(s):  
Water Transport ◽  
Powder Coating ◽  
Operating Conditions ◽  
Vapor Transport ◽  
Internal Stresses ◽  
Water Molecules ◽  
Epoxy Coatings ◽  
Water Permeation ◽  
Vapor Permeation ◽  
Self Association

Hydration of epoxy coatings reduces adhesion performance and causes degradation of the material, such as microstructural failures. Quantification of water vapor transport at elevated temperatures is fundamental to understanding polymer coating performance, especially when the coating is exposed to extreme operating conditions. As the water activity increases, the permeability/selectivity of polymers against other permeants changes. In this study, we examined the water permeation kinetics of two common epoxy-based powder coating systems for pipelines (fusion-bonded epoxy, FBE, and high-performance powder coating, HPPC) across a range of industrially-relevant temperatures (from room temperature to 80°C). Specifically, we utilized vapor permeation features of FBE and HPPC films with quantification of equilibrium flux as a function of temperature and pressure. In addition, we analyzed the nonlinear dependency of water transport on the vapor concentration at 65°C. The vapor transport analysis demonstrated that although data for FBE were indicative of a decrease in permeability around 65°C, perhaps due to self-association of water molecules, the coating was likely to experience a plasticization pressure around this temperature. We also examined microstructural changes of the epoxy network due to water transport. Our results revealed evidence of irreversible damage to epoxy coatings under wet-state conditions above 65°C. It appears that the combination of thermal exposure and internal stresses in the glassy epoxy lead to a phase separation of filler particles from the epoxy matrix, as well as to a distinctive cavity formation in the coating membrane. Yet, despite formation of percolating paths for water transport, our results indicate that vapor permeation is primarily restrained due to self-association of water molecules. The vapor transport flux and its permeance are lowered by one order of magnitude in the multilayered HPPC thanks to the moisture-resistant polyethylene topcoat, thus reducing the extent of damage to the underlying substrate. Since barrier protection against gas phase diffusion is controlled by the FBE primer, however, consequences of coating hydration are more pronounced in the overall selectivity toward gaseous transport. Hydrothermal exposure is likely to increase aggregate porosity of the coating and a conservative implementation of standard coating requirements is therefore reasonable to avoid early degradation issues.

scholarly journals Water Transport and Ion Diffusion Investigation of an Amphotericin B-Based Channel Applied to Forward Osmosis: A Simulation Study

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 646
Author(s):  
Hao-Chen Wu ◽  
Tomohisa Yoshioka ◽  
Keizo Nakagawa ◽  
Takuji Shintani ◽  
Hideto Matsuyama
Keyword(s):  
Amphotericin B ◽  
Water Transport ◽  
Water Permeability ◽  
Salt Water ◽  
Water Channel ◽  
Forward Osmosis ◽  
Water Molecules ◽  
Ion Leakage ◽  
Channel Models ◽  
Water Permeation

The use of an Amphotericin B_Ergosterol (AmBEr) channel as an artificial water channel in forward osmosis filtration (FO) was studied via molecular dynamics (MD) simulation. Three channel models were constructed: a common AmBEr channel and two modified C3deOAmB_Ergosterol (C3deOAmBEr) channels with different diameters (12 Å and 18 Å). During FO filtration simulation, the osmotic pressure of salt-water was a driving force for water permeation. We examined the effect of the modified C3deOAmBEr channel on the water transport performance. By tracing the change of the number of water molecules along with simulation time in the saltwater region, the water permeability of the channel models could be calculated. A higher water permeability was observed for a modified C3deOAmBEr channel, and there was no ion permeation during the entire simulation period. The hydrated ions and water molecules were placed into the channel to explore the ion leakage behavior of the channels. The mean squared displacement (MSD) of ions and water molecules was obtained to study the ion leakage performance. The Amphotericin B-based channels showed excellent selectivity of water molecules against ions. The results obtained on an atomistic scale could assist in determining the properties and the optimal filtration applications for Amphotericin B-based channels.

scholarly journals Characterization and modelling of air humidification in Fuel Cell System for transport sector

2022 ◽  
Vol 334 ◽  
pp. 06009
Author(s):  
Amedeo Grimaldi ◽  
Lorenzo Villa ◽  
Andrea Baricci ◽  
Stefano De Antonellis ◽  
Claudio Oldani ◽  
...  
Keyword(s):  
Water Transport ◽  
Transport Model ◽  
Cell System ◽  
Operating Conditions ◽  
Transport Sector ◽  
Counter Flow ◽  
Physical Description ◽  
Vapor Permeation ◽  
Individual Contributions ◽  
Transfer Properties

A model for the physical description of water transport through steady-state permeation and dynamic sorption within perfluoro-sulfonic acid (PFSA) membranes has been developed. A broad experimental campaign is conducted on several membranes, belonging to Aquivion class, varying both in thickness and equivalent weight (EW). The experimental data have been used to calibrate and validate water transport model and to find correlations for mass-transfer properties in low-EW PFSA membranes that describe consistently both water vapor permeation and sorption. It has been possible to identify individual contributions to mass transport resistance and to determine the optimal configuration and materials of a full-scale counter-flow membrane humidifier under a set of specific operating conditions.

Stereospecific Association of C-20 Epimers of 3β-Hydroxy-16-oxo-24-nor-17-azachol-5-eno-23-nitryle

1997 ◽  
Vol 52 (6) ◽  
pp. 749-756
Author(s):  
Zofia Plesnar ◽  
Stanisław Malanowski ◽  
Zenon Lotowski ◽  
Jacek W. Morzycki ◽  
Jadwiga Frelek ◽  
...  
Keyword(s):  
Proton Nuclear Magnetic Resonance ◽  
Side Chain ◽  
Water Molecules ◽  
Carbonyl Groups ◽  
Nmr Data ◽  
Molecular Modelling Studies ◽  
Modelling Studies ◽  
Lactam Carbonyl ◽  
Self Association ◽  
Chain Conformations

Abstract The cryoscopic measurements show that title compounds are strongly associated in CHCl3 solutions. The association of the 20 R epimer is distinctly less pronounced than that of the 20 S epipmer. Self-association of the 20 S epimer leads to the formation of very large com­plexes. The 20 R epimer forms associates via water molecules. The dissimilarity may be ex­plained in terms of different accessibility of the lactam carbonyl groups in the two epimers for the association. It is proposed that the association process is controlled by the configura­tion at the carbon atom C(20) and conformation around the C(20)-C(22) bond. Populations of side chain conformations of both epimers were determined by means of proton nuclear magnetic resonance. It was found for the 20 R epimer that the t and the -g rotamers are almost equally populated, and the rotamer +g is excluded. For the 20 S epimer the +g rotamer predominates over the t one, and the -g rotamer is excluded. The NMR data are fully consistent with the results of the molecular modelling studies.

scholarly journals Molecular dynamics study of pressure-driven water transport through graphene bilayers

2016 ◽  
Vol 18 (3) ◽  
pp. 1886-1896 ◽  
Author(s):  
Bo Liu ◽  
Renbing Wu ◽  
Julia A. Baimova ◽  
Hong Wu ◽  
Adrian Wing-Keung Law ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
High Pressure ◽  
Water Transport ◽  
Layered Structures ◽  
Water Molecules ◽  
Flow Rates ◽  
Ultra High Pressure ◽  
Pressure Driven Flow ◽  
Pressure Driven

Water molecules form layered structures inside graphene bilayers and ultra-high pressure-driven flow rates can be observed.

Quantification of water transport in a CO2 electrolyzer

2020 ◽  
Vol 13 (12) ◽  
pp. 5126-5134
Author(s):  
Danika G. Wheeler ◽  
Benjamin A. W. Mowbray ◽  
Angelica Reyes ◽  
Faezeh Habibzadeh ◽  
Jingfu He ◽  
...  
Keyword(s):  
Water Transport ◽  
3D Model ◽  
Operating Conditions ◽  
Variable Operating Conditions

The distribution and flow of water in a CO2 electrolyzer can be defined at variable operating conditions using a 3D model coupled with an analytical electrolyzer.

scholarly journals Interfacial Water Transport Effects in Proton-Exchange Membranes

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Brian Kientiz ◽  
Haruhiko Yamada ◽  
Nobuaki Nonoyama ◽  
Adam Z. Weber
Keyword(s):  
Experimental Data ◽  
Fuel Cell ◽  
Water Transport ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Polymer Electrolyte Fuel Cell ◽  
Interfacial Resistance ◽  
Fuel Cell Performance ◽  
Membrane Interfaces

It is well known that the proton-exchange membrane is perhaps the most critical component of a polymer-electrolyte fuel cell. Typical membranes, such as Nafion®, require hydration to conduct efficiently and are instrumental in cell water management. Recently, evidence has been shown that these membranes might have different interfacial morphology and transport properties than in bulk. In this paper, experimental data combined with theoretical simulations that explore the existence and impact of interfacial resistance on water transport for Nafion®21x membranes will be presented. A mass-transfer coefficient for the interfacial resistance is calculated from experimental data using different permeation cells. This coefficient is shown to depend exponentially on relative humidity or water activity. The interfacial resistance does not seem to exist for liquid/membrane or membrane/membrane interfaces. The effect of the interfacial resistance is to flatten the water content profiles within the membrane during operation. Under typical operating conditions, the resistance is on par with the water transport resistance of the bulk membrane. Thus, the interfacial resistance can be dominant especially in thin, dry membranes and can affect overall fuel cell performance.

Effect of Operating Conditions on the Water Transport Phenomena at the Cathode of Polymer Electrolyte Membrane Fuel Cell

2009 ◽  
Author(s):  
Sang Hern Seo ◽  
Chang Sik Lee
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Water Transport ◽  
Flow Rate ◽  
Water Droplet ◽  
Polymer Electrolyte Membrane ◽  
Transport Phenomena ◽  
Operating Conditions ◽  
Water Flooding ◽  
Electrolyte Membrane

Water management is very important for polymer electrolyte membrane fuel cell because the fuel cell performance is decreased by flooding phenomena generated by liquid water in the cathode channels. In addition, the proton conductivity and water transport of membrane could become different by hydration contents of membrane. This study is observed water transport phenomena of cathode channels with a polymer electrolyte membrane fuel cell according to various operating conditions. In order to obtain the water images, the transparent fuel cell consists of polycarbonate window of the cathode end plate and gold coated stainless steel as the flow field and current collector of the cathode. To investigate the effects of operating conditions on the water transport, experiments were conducted under various operating conditions such as cell temperature, cathode flow rate and cathode backpressure. As operating time elapsed, it is observed that the water droplet formation, growth, coalescence and removal occurred in the cathode channel. It can be known that the high cathode flow rate prevents water flooding by removal of water in the cathode flow channel. Also, the quantity of water droplet was increased by the high cathode backpressure.

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