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1
Kreisz, Aurélien. "Membranes PBI pour pile à combustible haute température." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT224.
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Cette thèse débute par une courte introduction traitant des principes et de l'état de l'art des PEMFC dans le but de situer le contexte des travaux. Le but des travaux présentés dans ce manuscrit est de développer une nouvelle méthode de préparation de membrane pour les piles à combustible haute température (> 120 °C). Le polybenzimidazole dopé à l'acide phosphorique est devenu la référence des PEM haute température. Un degré de dopage élevé est essentiel pour minimiser les pertes ohmiques dans la cellule. Malheureusement un degré de dopage élevé entraine aussi une plastification de la membrane détériorant aussi sa résistance mécanique. Il est donc essentiel d'atteindre un compromis entre conductivité protonique élevée et résistance mécanique en contrôlant le degré de dopage. Dans ce travail, nous avons développé une nouvelle méthode de préparation de membrane, basée sur la gélation thermoréversible d'une solution de PBI dans l'acide phosphorique ou polyphosphorique, dans le but d'obtenir des degrés de dopage élevés. Une modification chimique a été réalisée dans l'état dopé afin d'induire une réticulation du polymère. De plus, les résistances mécaniques ont été améliorées en introduisant dans la membrane un mat de PBI réticulé obtenu par filage électrostatique. La faisabilité des approches suivies dans ces travaux a été démontrée par des tests en cellule de pile à combustible jusqu'à une température de 180 °C. Les AMEs élaborés à partir de ces membranes ont montré une stabilité satisfaisante durant 900 - 1000 heures de fonctionnement sous conditions statiques (opération continue à 0.2 A.cm-2) et sous conditions dynamiques (cyclage en tension et courant) avec une décroissance de la tension de la cellule au cours du temps de 0.7 - 0.8 µV.h-1 à 0.2 A.cm-2. Les caractéristiques I-V de ces AMEs ont été comparées à des assemblages de référence PBI/H3PO4 commerciaux et ont présenté des performances améliorées par rapport aux assemblages commerciaux<br>The thesis begins with a short overview of the principles and the current state at the art of the PEMFC in order to give a background on the specific subject of high temperature PEM fuel cell. The aim of the work presented in this thesis is to develop a new method of preparation of membrane for high temperature fuel cell (T > 120 °C). Phosphoric acid doped PBI has become the reference for high temperature PEM. A high phosphoric acid content is essential to minimize the ohmic voltage loss in the fuel cell for high current density. Unfortunately high phosphoric acid content exerts a strong plasticizing effect resulting in poor mechanical properties of the membrane. Consequently the doping level of the membrane should be a compromise between the highest proton conductivity and mechanical strength. In this work we have presented a new method of preparation of membrane based on the thermoreversible gelation of a PBI solution in phosphoric or polyphosphoric acid in order to obtain high acid doping. The chemical modification of the membrane has been performed in the doped state in order to induce a chemical crosslinking. The mechanical strength of the membrane has been further improved by the introduction of PBI electrospun mat as reinforcement. The feasibility of the approaches followed in this work was demonstrated in fuel cell tests at temperature up to 180 °C. The MEA based on those membranes have shown a stability up to 900 - 1000 hours either under static (continuous operation at 0.2 A.cm-2) or dynamic (voltage and current cycling) operation with a small voltage decay of 0.7 - 0.8 µV.h-1 at 0.2 A.cm-2. The I-V characteristics of these MEA have been compared with reference commercial PBI/H3PO4 MEAs and shown improved performances
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Suarez, Matthew. "The Effect of Membrane Thickness on the Performance of PBI-Based High-Temperature Direct Methanol Fuel Cells." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/1131.
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"This project investigates the effect of membrane thickness on the performance and durability of a Direct Methanol Fuel Cell (DMFC) using a commercially available Celtec®P-1000 PBI-based membrane electrode assembly (MEA). The PBI-based membranes tested were the 100µm, the standard thickness, 200µm and 250µm thick. With various methanol feed concentrations and cathode feeds, oxygen and air, the PBI-based MEAs were operated between 160 and 180°C with vaporized methanol feed. Results showed that the DMFC performance increased with temperature and with PBI membrane thickness. The optimal concentration for the 100µm membrane was at 5M while the best performance with the 200µm membrane was obtained at 3M. The 250µm membrane looked like it could have had better performance than the 200µm, but unfortunately experimental issues didn’t allow completion of these results."
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Gomes, Carlos André Mendonça. "Study of multi-component systems in polybenzimidazole membrane formation and their impact on membrane performance." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10651.
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Dissertação para obtenção do Grau de Mestre em
Engenharia Química e Bioquímica<br>Integrally skinned asymmetric polybenzimidazole (PBI) membranes suitable for organic solvent nanofiltration (OSN) were prepared via phase inversion and several changes were implemented in the
dope solutions in order to control their molecular weight cut-off (MWCO). Initially, uncrosslinked membranes with different polymer concentrations were tested to investigate their impact on membrane performance. On a second approach, several co-solvents were added in the dope
solutions of PBI membranes. Coupling this methodology with chemical crosslinking, using an aromatic bi-functional crosslinker, provided solvent stable membranes with several MWCOs in the nanofiltration range and high permeance. Further variation of membrane dope parameters was tested in order to study membrane formation impact on membrane performance. Total solubility parameters of the chosen co-solvents were calculated, and a correlation between this tool and membrane performance was studied. Even though it was not possible to withdraw conclusions on a fundamental level, from the
correlation of the total solubility parameters with membrane performance, this work demonstrates the possibility of developing PBI OSN membranes using different co-solvents and opens up future possibilities for controlling the MWCO of these membranes. A post-treatment study was also conducted in order to examine its impact in membrane performance.
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Barrientos, Wilner Valenzuela. "Estudo dos parâmetros operacionais de uma célula a combustível de glicerol direto utilizando uma membrana de polibencimidazol impregnada com ácido fosfórico (PBI/H3PO4) ou 1-hexil-3-metilimidazol trifluorometanosulfo." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-15092015-135733/.
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Com o aumento da população mundial, o desenvolvimento de novas fontes e conversores de energia tornou-se uma necessidade. As células a combustível mostram-se como uma alternativa viável devido principalmente a duas razões, sua alta eficiência e a utilização de combustíveis renováveis. No presente trabalho se estuda a influência da temperatura de operação e o conteúdo de álcali no combustível sobre a densidade de potencia para uma célula a combustível de glicerol direto. Como combustível foi utilizado uma solução de glicerol:KOH (1M:xM, x=0, 1, 3, 5), como membranas foram utilizados filmes de polibencimidazol impregnado com ácido fosfórico (PBI/H3PO4, relação molar 1:11) ou 1-hexil-3-metilimidazol trifluorometanosulfonato (PBI/HMI-Tf relação molar 1:1.5), e finalmente, nano partículas de Pt suportadas em carbono (60% w/w) como catalizador no ânodo e no cátodo. Em geral, o incremento da temperatura e conteúdo de álcali no combustível mostra um efeito favorável na densidade de potencia do sistema. Numa célula a combustível unitária de glicerol direto utilizando membranas de PBI/ H3PO4 e PBI/HMI-Tf foram obtidas densidades de potencia de 0.54mW.cm-2 a 175°C e 0.599mW.cm-2 a 130°C, respectivamente, para uma solução de glicerol de (1M); enquanto que, para uma solução com um conteúdo maior de álcali, glicerol:KOH (1M:5M), foram obtidas densidades de potencia maiores, 44.1mW.cm-2 a 175°C e 29mW.cm-2 a 130°C, respectivamente. O efeito combinado do incremento da temperatura e concentração de álcali no combustível mostra um efeito maior em relação ao efeito só da temperatura.<br>With the increasing world population, the development of new energy sources or energy converters has become a necessity. Fuel cells show up as a viable alternative due mainly to two reasons, their high efficiency and the use of renewable fuels. In the present work we study the influence of operating temperature and alkali content in the fuel on the power density for a direct glycerol fuel cell. A glycerol:KOH (1M: xM, x = 0, 1, 3, 5) solution was used as fuels, as membranes were used polibencimidazol films impregnated with phosphoric acid (PBI/H3PO4, molar ratio of 1:11) or 1-hexyl-3-methylimidazolium trifluoromethanesulfonate (PBI/HMI-Tf), and finally, Pt nanoparticles supported on carbon (60% w / w) as catalyst in the anode and cathode. In general, increasing the temperature and alkali content in the fuel shows a favorable effect in the system power density. In a direct glycerol fuel cell using PBI/H3PO4 and PBI /HMI-Tf membranes were obtained power density of 0.54mW.cm-2 at 175°C and 0.599mW.cm-2 at 130°C, respectively, for a 1M glycerol solution; while for a glycerol solution with a higher content of alkali, glycerol:KOH (1M: 5M), were obtained higher power densities, 44.1mW.cm-2 at 175 ° C and 29mW.cm-2 at 130 ° C, respectively. The combined effect of increased temperature and alkali concentration in the fuel shows a greater effect compared to the effect of temperature only.
5
Lee, Jeong Kyu. "Direct Methanol Fuel Cell Membranes from Polymer Blends." Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1134316195.
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Basdemir, Merve. "Development Of Pbi Based Membranes For H2/co2 Separation." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615473/index.pdf.
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Recent developments have confirmed that in the future hydrogen demand in industrial applications will arise because of the growing requirements for H2 in chemical manufacturing, petroleum refining, and the newly emerging clean energy concepts. Hydrogen is mainly produced from the steam reforming of natural gas and water gas shift reactions. The major products of these processes are hydrogen and carbon dioxide. The selective removal of CO2 from the product gas is important because it poisons catalysts in the reactor and it is highly corrosive. Membrane separation processes for hydrogen purification may be employed as alternative for conventional methods such as adsorption, cryogenic distillation.
Mixed matrix membranes (MMMs) are composed of an insoluble phase dispersed homogeneously in a continuous polymer matrix. They have potential in gas separation applications by combining the advantageous properties of both phases. The objective of this study is to produce neat polybenzimidazole (PBI) membranes and PBI based mixed matrix membranes for separation of H2/CO2. Furthermore, to test the gas permeation performance of the prepared membranes at permeation temperatures of 35oC to 90oC.
Commercial PBI supplied from both Celanese and FumaTech were used as polymer matrix. PBI was selected based on its thermal, chemical stabilities and mechanical properties and its performance as a fuel-cell membrane produced by PBI.
Micro-sized Zeolite 3A and nano-sized SAPO-34 are zeolites with 0.30 nm and 0.38 nm pore size respectively have attracted considerable interest and employed as fillers in this study. Commercial Zeolite 3A and synthesized SAPO-34 by our group was used throughout the study. Membranes were prepared using N,N-dimethylacetamide as the solvent. Prepared membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The effect of annealing procedure and operating temperature on gas separation performance of resultant neat PBI, PBI/Zeolite 3A and PBI/SAPO-34 membranes were investigated by gas permeation tests. Hydrogen and carbon dioxide gases were used for single gas permeation measurements. Two different annealing strategies were utilized namely in-line annealing and in-oven annealing. In-oven annealing was performed in an oven in nitrogen atmosphere at 120oC, 0.7 atm while in-line annealing was performed in the gas permeation set-up by feeding helium as permeating gas at 90oC and 3 bar.
Neat PBI and PBI/ Zeolite 3A membranes were in-oven annealed. The in-oven annealed membranes showed better selectivities with lower permeabilities, but the performance results of these membranes had low repeatability. On the other hand, in-line annealed membranes showed much higher permeabilities and lower selectivities with stable performance. By changing the annealing method hydrogen permeability increased from 5.16 Barrer to almost 7.77 barrer for neat membranes and for PBI/Zeolite 3A mixed matrix membranes increased from 5.55 to to 7.69 Barrer at 35oC. The selectivities were decreased from 6.21 to 2.31 for neat membranes and for PBI/Zeolite 3A from 5.55 to 2.63.
Effect of increasing operating temperature was investigated by using in-line annealed membranes. Increasing temperature from 35oC to 90o improved the performance of the both types of membranes and repeatable results were obtained. Besides neat PBI and PBI/Zeolite 3A, PBI/SAPO-34 membranes were prepared only via in-line annealing. The addition of nano-sized filer to the membranes provided homogeneous distribution in polymer matrix for PBI/SAPO-34 membranes. For this type of membrane hydrogen permeability increased from 8.01 to 26.73 Barrer and with no change in H2/CO2 selectivities via rising temperature. Consequently, it is better to study hydrogen and carbon dioxide separation at high temperature.
For all types of membranes hydrogen showed higher activation energies. In between all membranes magnitude of activation energies were the highest for PBI/SAPO-34 membrane which is an indication of good interaction between polymer and zeolite interface. In-line annealed membranes gave the best gas permeation results by providing repeatability of measurements. Among all studied membranes in-line annealed PBI/SAPO-34 membrane exhibited the best gas permeation results.
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Schoeman, Johannes Gerhardus. "H2SO4 stability of PBI–blend membranes for SO2 electrolysis Schoeman / H." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7567.
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Alternative energy sources are needed if the current use of energy is to be sustained while
reducing global warming. A possible alternative energy source that has significant potential
is hydrogen. For hydrogen to become a serious contender for replacing fossil fuels, the
production thereof has to be further investigated. One such process, the membrane–based
Hybrid Sulphur (HyS) process, where hydrogen is produced from the electrolysis of SO2, has
received considerable interest recently.
Since H2SO4 is formed during SO2 electrolysis, H2SO4 stability is a prerequisite for any
membrane to be used in this process. In this study, pure as well as high and low
temperature blended polybenzimidazole (PBI), partially fluorinated poly(arylene ether) (sFS)
and nonfluorinated poly(arylene ethersulphone) (sPSU) membranes were investigated in
terms of their acid stability as a function of acid concentration by treating them in H2SO4 (30,
60 and 90wt%) for 120h at 1bar pressure. The high temperature blend membranes contain
the basic polymer in excess (70 wt% basic PBI and 30wt% acid sPSU/sFS polymer) and
require acid doping in order to conduct protons. In the doped state they are able to conduct
protons up to 200°C. The low temperature blend membranes are also composed of the
same PBI polymer used in the high temperature membranes, as well as the same acidic
polymers with one of the membranes containing a fluorinated polymer and the other a nonfluorinated
polymer (sFS or sPSU) in excess. These membranes do not require any acid
doping to conduct protons but they are only stable at temperatures below 80°C.
High temperature blend membranes were characterised using through–plane conductivity,
GPC and IEC, whilst low temperature membranes were characterised using in–plane and
through–plane proton conductivity, weight change, TGA, GPC, SEM, EDX and IEC
techniques. The conductivity determination techniques (especially the in–plane technique)
proved to be cumbersome, whilst all the other analysis techniques were deemed
appropriate.
H2SO4 exposure had a destabilising effect on the PBI membrane which presented as weight
gain at the 30 and 60wt% H2SO4 concentrations due to salt formation and dissolution at the
90wt% acid treatment due to sulphonation. In the sFS membrane dissolution was observed
at 30 and 60wt% as a result of oligomer loss that occurred during the post treatment
washing process and partial dissolution, as a result of sulphonation, at the 90wt% treated membrane. The sPSU membrane showed great stability at 30 and 60wt%, though
dissolution was observed at 90wt% because of membrane sulphonation due to a lack of
fluorination. The sFS–PBI membrane blend proved to be stable with only slight degradation
taking place at 90wt% treatment due to sulphonation. Similarly the sPSU–PBI blend
membrane showed great stability at the 30 and 60wt% H2SO4 treatment concentrations
however total dissolution occurred at 90wt% treatment again due to a lack of fluorination.
Although both the low temperature blended membranes showed superb stability to H2SO4
concentrations expected in the SO2 electrolyser (30–40wt%), the low temperature blended
sFS–PBI membrane seemed slightly more stable over the H2SO4 treatment concentration
range (30–90wt%), due to the protective role of the fluorinated polymer. The superior acid
stability of this membrane could prove vital for proper SO2 electrolysis, especially for
prolonged periods of operation<br>Thesis (M.Sc. (Pharmaceutical Chemistry))--North-West University, Potchefstroom Campus, 2012.
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Freitas, Mauricio Azevedo de. "Poli(indeno) fosfonado : síntese, propriedades e uso como eletrólito em membranas a base de PBI." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/181807.
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Neste trabalho, um polímero eletrólito derivado do poli(indeno) (PInd) foi desenvolvido como componente de membranas poliméricas a base de polibenzimidazol (PBI) para célula a combustível de média temperatura. Foi investigado o método de síntese, envolvendo a reação de fosfonação pelo método de Friedel-Crafts assistido por catalisador ácido de Lewis AlCl3. O polímero poli(indeno) fosfonado (PPInd) foi comparado com seu análogo sulfonado, o poli(indeno) sulfonado (SPInd), e usados nas blendas com 5, 7,5 e 10% em peso com o PBI. Os polímeros precursores foram caracterizados por espectroscopia de infravermelho, espectroscopia de ressonância magnética nuclear, espectroscopia de energia dispersiva, espectrometria de espalhamento Rutherford, análise termogravimétrica acoplada com espectrometria de massas e calorimetria exploratória diferencial. As blendas PPInd/PBI e SPInd/PBI foram caracterizadas por análise termogravimétrica, grau de dopagem e espectroscopia de impedância eletroquímica. A modificação realizada pelo método de Friedel-Crafts permitiu a obtenção do poli(indeno) fosfonado parcialmente solúvel em solventes orgânicos e água, com grau de modificação de 81%. Houve convergência dos teores de modificação encontrados pelas análises termogravimétrica, espectrometria de espalhamento Rutherford e espectroscopia de energia dispersiva. O polímero PPInd apresentou estabilidade química na temperatura de operação da célula a combustível de média temperatura, passando por processos de degradação típicos de sua estrutura aromática fosfonada. A degradação dos polímeros PInd, PPInd e SPInd ocorreu majoritariamente com cisão de unidades monoméricas de indeno não funcionalizado. A inserção dos polímeros modificados PPInd e SPInd no PBI resultou no aumento da condutividade iônica, tendo a blenda com 10% de PPInd apresentado o maior valor de condutividade protônica (0,015 S.cm-1), a 25 oC. O uso do poli(indeno) modificado com grupos ácido fosfônico visa aumentar a gama de eletrólitos para células a combustível de média temperatura.<br>In this work a polymer electrolyte derivated from the poly(indene) (PInd) was developed to be used as polymer electrolyte membrane in medium-temperature fuel cells. The modification method, based on the AlCl3 assisted Friedel-Crafts reaction, was investigated as fosfonation strategy. The phosphonated poly(indene) was compared to its similar sulphonated poly(indene) and they were used in blends of 5, 7.5 and 10wt% in polybenzimidazole (PBI). Pristine polymers were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, energy dispersive spectroscopy, Rutherford backscattering spectrometry, thermogravimetric analysis coupled with mass spectrometry and differential scanning calometry. The PPInd/PBI and SPInd/PBI blends were characterized by thermogravimetric analysis, doping level and electrochemical impedance spectroscopy. The modification by Friedel-Crafts reaction produced phophonated poly(indene) with degree of phosphonation of 81%, partially soluble in organic solvent and water. It was found convergence on the results for degree of phosphonation calculated by thermogravimetric analysis, Rutherford backscattering spectrometry and energy dispersive spectroscopy. PPInd presented chemical and thermal stabilities within the fuel cell operating temperature, passing by typical degradation processes of macromolecules made of phosphonated aromatic structures. The degradation of PPInd and SPInd occurred mainly by cleavage of monomeric units of non-funcionalized indene. Addition of modified polymers PPInd and SPInd resulted in increase of PBI’s ionic conductivity. 10PPInd/PBI blend presented the highest ionic conductivity (0.015 S.cm-1) at 25 oC. The use of phosphonated poly(indene) on PBI membranes enlarges the variety of available polymer electrolyte membranes for medium-temperature fuel cells.
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Petek, Tyler Joseph. "An Investigation of PBI/PA Membranes for Application in Pump Cells for the Purification and Pressurization of Hydrogen." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1320704555.
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Fattori, Enrico. "Membrane elettrofilate ibride a base di PBS e cheratina per il rilascio controllato di farmaci." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18569/.
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Grazie agli sviluppi delle nanotecnologie biomedicali nell’ambito del rilascio controllato di farmaci, sta diventando sempre più concreta la possibilità di superare i principali limiti della medicina tradizionale, basata su somministrazioni frequenti e ripetute di quantità di principio attivo anche superiori rispetto a quelle necessarie, e che dopo poco tempo raggiungono livelli al di sotto della soglia di efficacia. Tramite lo studio dei biomateriali e delle loro proprietà è possibile realizzare soluzioni ad hoc per il rilascio mirato di farmaco nel sito in cui è richiesta la terapia, con cinetiche modulabili a seconda delle specifiche esigenze del paziente. Nel presente studio, è stato realizzato mediante elettrofilatura un cerotto (o patch) a partire da una blend fisica di poli(butilene succinato) (PBS) e cheratina. Il primo è un polimero sintetico biocompatibile e approvato dalla Food and Drug Administration, con buone resistenza meccanica e lavorabilità, ma tempi di degradazione piuttosto lenti, a differenza della cheratina, polimero naturale, che risulta troppo rigido e difficile da processare, ma con buoni tempi di degradazione ed un’ottima biocompatibilità. Il tappetino elettrofilato così ottenuto è stato sottoposto a caratterizzazione molecolare, termica e meccanica. Inoltre, in vista di possibili applicazioni nell’ambito del rilascio controllato di farmaco, alla stessa blend è stato aggiunto diclofenac, antinfiammatorio presente in commercio, per ottenere una patch contenente al suo interno la stessa quantità di principio attivo presente nei comuni cerotti medicati. Il tappetino è stato sottoposto anche a test di rilascio del farmaco in condizioni fisiologiche e a test di adesione alla pelle. In conclusione, ogni tipo di indagine, seppur preliminare, ha comprovato che l’unione tra il PBS e la cheratina ha dato vita ad un nuovo biomateriale facilmente processabile, adesivo, ed in grado di favorire il rilascio del farmaco contenuto al suo interno.
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Sforzini, Matteo. "Membrane elettrofilate biodegradabili a base di PBS e cheratina per il rilascio di farmaci ed ingegneria tissutale." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19192/.
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Grazie agli sviluppi delle nanotecnologie biomedicali nell’ambito del rilascio controllato di farmaci e dell’ingegneria tissutale, sta diventando sempre più concreta la possibilità di superare i principali limiti della medicina tradizionale, basata nel primo caso su somministrazioni ripetute e a livello sistemico di principio attivo, e nel secondo caso sul trapianto (con relativi problemi di rigetto e carenza di donatori) e su trattamenti farmacologici non risolutivi. Tramite lo studio dei biomateriali e delle loro proprietà è invece possibile realizzare soluzioni ad hoc per l’ingegneria tissutale e per il rilascio controllato e mirato di farmaco. Nel presente studio, sono stati realizzati, mediante elettrofilatura, scaffolds a partire da blend fisiche di poli(butilene succinato) (PBS) e cheratina, a diversa composizione. Il primo è un polimero sintetico biocompatibile e approvato dalla Food and Drug Administration, con buone resistenza meccanica e lavorabilità, ma tempi di degradazione piuttosto lenti, a differenza della cheratina, polimero naturale, che risulta troppo rigido e difficile da processare, ma con buoni tempi di degradazione ed un’ottima biocompatibilità. Le blend sono state sottoposte a studi di miscibilità, mentre sui tappetini elettrofilati è stata effettuata una caratterizzazione morfologica, termica e meccanica. Inoltre, in vista di possibili applicazioni nell’ambito dell’ingegneria tissutale e del rilascio controllato di farmaco, si sono svolti anche test di biodegradazione in ambiente enzimatico e prove di biocompatibilità in vitro, nel primo caso, e studi di rilascio di diclofenac, comune antinfiammatorio, e test di adesione alla pelle, nel secondo caso. In conclusione, ogni tipo di indagine, seppur preliminare, ha comprovato che l’unione tra il PBS e la cheratina ha dato vita a nuove miscele facilmente processabili per potenziali utilizzi in due ambiti biomedicali di particolare interesse applicativo.
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Pierini, Giulia. "Preparation and characterization of grafted nonwoven membranes for bioseparations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11903/.
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Protein purification plays a crucial role in biotechnology and biomanufacturing, where downstream unit operations account for 40%-80% of the overall costs. To overcome this issue, companies strive to simplify the separation process by reducing the number of steps and replacing expensive separation devices. In this context, commercially available polybutylene terephthalate (PBT) melt-blown nonwoven membranes have been developed as a novel disposable membrane chromatography support. The PBT nonwoven membrane is able to capture products and reduce contaminants by ion exchange chromatography. The PBT nonwoven membrane was modified by grafting a poly(glycidyl methacrylate) (GMA) layer by either photo-induced graft polymerization or heat induced graft polymerization. The epoxy groups of GMA monomer were subsequently converted into cation and anion exchangers by reaction with either sulfonic acid groups or diethylamine (DEA), respectively. Several parameters of the procedure were studied, especially the effect of (i) % weight gain and (ii) ligand density on the static protein binding capacity. Bovine Serum Albumin (BSA) and human Immunoglobulin G (hIgG) were utilized as model proteins in the anion and cation exchange studies. The performance of ion exchange PBT nonwovens by HIG was evaluated under flow conditions. The anion- and cation- exchange HIG PBT nonwovens were evaluated for their ability to selectively adsorb and elute BSA or hIgG from a mixture of proteins. Cation exchange nonwovens were not able to reach a good protein separation, whereas anion exchange HIG nonwovens were able to absorb and elute BSA with very high value of purity and yield, in only one step of purification.
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Bondi, Edoardo. "Membrane elettrofilate di cheratina e poli(butilene succinato): effetti della composizione della miscela sulle proprietà chimico-fisiche delle membrane e sulla cinetica di rilascio di farmaci." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23187/.
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In ambito biomedicale una delle applicazioni che ad oggi sta riscuotendo un interesse crescente è lo studio di dispositivi performanti per il rilascio controllato di farmaci. La realizzazione di materiali nanofibrosi a base di polimeri di origine naturale e sintetica costituisce una strada molto interessate. In particolare, la cheratina, che può essere ricavata da un’ampia quantità di sottoprodotti delle industrie zootecniche e tessili, presenta ottima biocompatibilità e caratteristiche che le consentono di svolgere il ruolo di carrier per molteplici tipologie di sostanze. La fragilità e la difficile processabilità della cheratina possono essere migliorate mediante miscelazione con polimeri di origine sintetica, come il poli(butilene succinato) (PBS), un poliestere alifatico biodegradabile e biocompatibile, caratterizzato da un buona stabilità termica e da ampia lavorabilità. Nel presente lavoro di Tesi sono state realizzate miscele e membrane elettrofilate a base di PBS e cheratina a diversa composizione, ed è stato valutato l'effetto della composizione sulle proprietà chimico-fisiche delle membrane elettrofilate e sulla cinetica di rilascio di farmaci. Per prima cosa è stata analizzata la stabilità della cheratina nel solvente; sono state quindi svolte analisi sul comportamento reologico delle miscele in tre rapporti di peso ed i tappetini elettrofilati sono stati caratterizzati da un punto di vista morfologico (SEM), termico (TGA e DSC) e meccanico (prove di trazione e di adesione). Le prove di rilascio sono state effettuate impiegando rodamina, una molecola modello, e le membrane sono state analizzate prima e dopo il rilascio tramite FTIR, per valutare eventuali variazioni compositive. Dai risultati ottenuti, emerge che è stato possibile modulare sia le proprietà delle membrane sia i profili di rilascio, agendo semplicemente sulla composizione delle miscele, ad indicare un’ampia versatilità per applicazioni in ambito di rilascio controllato di farmaco.
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Hailesilassie, Biruk Wobeshet. "Mechanisms of Blister Formation on Concrete Bridge Decks with Waterprooving Asphalt Pavement Systems." Licentiate thesis, KTH, Väg- och banteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-124078.
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Bridge decks are commonly subjected to harsh environmental conditions that often lead to serious corrosion problems triggered by blisters under the hot mix asphalt bridge deck surfacing and secretly evolving during weather exposure until damage is often detected too late. Blisters may form under both the waterproofing dense mastic asphalt layer or under the waterproofing membrane which is often applied as additional water protection under the mastic asphalt (MA). One of the main technical issues is the formation of blisters under the membrane and asphalt-covered concrete structures caused by a complex mechanism governed by bottom-up pressure and loss of adhesion. A linear viscoelastic finite-element model was developed to simulate time-dependent blister growth in a dense mastic asphalt layer under uniformly applied pressure with and without temperature and pressure fluctuation. A finite element model was developed using ABAQUS with linear viscoelastic properties and validated with a closed form solution from first-order shear-deformation theory for thick plates. In addition, the blister test was conducted on different samples of MA in the laboratory and digital image correlation measurement technique was used to capture the three-dimensional vertical deflection of the MA over time. It was found that the blister may grow continuously under repeated loading conditions over subsequent days. With respect to blistering under waterproofing membranes, mechanical elastic modeling and experimental investigations were performed for three different types of membranes under in-plane stress state. The orthotropic mechanical behavior of a polymer modified bitumen membrane (PBM) was determined from biaxial test data. Finally, blister tests by applying controlled pressure between orthotropic PBMs and concrete plates were performed for studying the elliptical adhesive blister propagation using digital 3D image correlation. The energy calculated from elliptical blister propagation was found comparable to the adhesive fracture energy from standard peeling tests for similar types of PBMs. This indicates that the peeling test assists to evaluate and rank the adhesive properties of different types of membranes with respect to blister formation at room temperature without conducting time consuming and complicated pressurized blister propagation tests using digital 3D image correlation.<br><p>QC 20130625</p>
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Socrier, Larissa. "Influence de la localisation d’antioxydants sur la peroxydation des lipides membranaires : étude du mode d’action de dérivés PBN et de composés phénoliques." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2382/document.
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Les espèces réactives de l’oxygène (EROs) sont essentielles à la survie des cellules car elles interviennent dans divers processus physiologiques comme la défense immunitaire ou encore la régulation de voies de signalisation cellulaires. Cependant, un excès d’EROs peut créer un déséquilibre de la balance EROs/antioxydants appelé « stress oxydant ». Le stress oxydant étant impliqué dans l’étiologie de plus de 200 pathologies, l’action des antioxydants est cruciale pour limiter les effets délétères des EROs. Les antioxydants utilisés par les cellules peuvent être de nature chimique. Parmi ceux-ci, l’α-phenyl-N-tert-butyl nitrone (PBN) est particulièrement efficace en milieu biologique pour piéger les radicaux. Cependant, comme cette molécule présente le désavantage majeur de mal cibler les membranes, des nitrones amphiphiles dérivées de la PBN ont été synthétisées. Le premier chapitre décrit l’étude des interactions de nitrones dérivées du cholestérol avec les lipides membranaires. Ces travaux ont souligné l’influence du groupement polaire sur la nature des interactions avec les lipides membranaires. Aussi, l’étude des propriétés antioxydantes a permis de mettre en évidence l’importance de la localisation membranaire et l’influence de l’orientation du groupement PBN sur l’activité protectrice des dérivés. Le second chapitre décrit les résultats des expériences menées avec une deuxième série de dérivés amphiphiles, présentant la particularité d’avoir une chaîne perfluorée comme groupement hydrophobe. Bien que la localisation membranaire de ces dérivés soit nécessaire pour obtenir un effet protecteur significatif, la nature de l’antioxydant semble être ici le paramètre le plus important. Enfin, la combinaison d’antioxydants de nature différente sur une même molécule semble être une stratégie prometteuse pour améliorer l’efficacité antioxydante et créer un effet de synergie. En outre, pour se défendre, les cellules utilisent aussi des antioxydants issus de l’alimentation, en particulier des fruits et légumes. Parmi ces derniers, les composés phénoliques sont reconnus pour leurs effets bénéfiques sur la santé. Les flavonoïdes, les acides phénoliques, les stilbènes et les lignanes constituent les 4 classes principales de composés phénoliques. Les lignanes sont particulièrement présents dans les graines de lin (Linum usitatissimum). Le lin est la plante qui contient le plus de secoisolaricirésinol diglucoside. Afin de mieux comprendre leur fonctionnement et leurs interactions avec les lipides membranaires, plusieurs molécules appartenant à cette classe de composés ainsi que des acides hydroxycinnamiques ont été purifiées à partir du lin. Le troisième chapitre décrit les résultats des expériences menées avec les composés phénoliques extraits du lin. De manière générale, les composés testés se sont avérés efficaces pour protéger les lipides membranaires de l’oxydation. L’étude de leurs interactions avec les lipides membranaires a permis de montrer que le mode d’action des lignanes, qui pénètrent les membranes, est plus efficace que celui des acides hydroxycinnamiques<br>Reactive oxygen species (ROS) are essential in living cells as they intervene in several physiological processes like the immune system and signaling pathways. However, an excess of the production of ROS can alter the equilibrium with antioxidants. This imbalance is called oxidative stress. As oxidative stress has been reported to be implicated in more than 200 diseases, the action of antioxidants to limit the deleterious effects of ROS is crucial. The antioxidants used by the cells can be chemical. Among them, α-phenyl-N-tert-butyl nitrone (PBN) is widely used in biological systems to neutralize ROS. Because this molecule possesses a poor ability to target membranes, our collaborators synthesized amphiphilic nitrones bearing a PBN moiety. The first chapter describes the interactions of cholesterol derived PBN derivatives with the membrane. Results underlined the influence of the polar moiety on the nature of their interactions with membrane lipids. In addition, the evaluation of the antioxidant properties revealed the importance of the membrane localization of the nitrone moiety on the protective activity of the derivatives. The second chapter deals with a second set of amphiphilic nitrones that have the particularity of bearing a perfluorinated chain that constitutes the hydrophobic moiety. We noticed the membrane localization is important for the antioxidant efficiency; however the nature of the antioxidant moiety remains the most important parameter in this case. Finally, the strategy of grafting two different antioxidants on the same carrier seems to be promising to enhance the protective effect and create a synergistic antioxidant effect. However, cells also use natural antioxidants to defend themselves. These antioxidants come from food, especially from vegetables and fruits. Among them, phenolic compounds are known for their beneficial effects on health. Flavonoïds, phenolic acids, stilbenes and lignans constitute the 4 main classes of phenolic compounds. Lignans are particularly present in flaxseed (Linum usitatissimum). Flaxseed is the plant that possesses the highest quantity of secoisolariciresinol diglucoside. In order to understand their mechanisms of action and their interactions with membranes, lignans as well as hydroxycinnamic acids were purified from flaxseed. The third chapter describes the results obtained on model membranes. Generally speaking, both classes of compounds are efficient against lipid oxidation. Studying their interactions with membrane lipids allowed us to show that the mechanism of lignans, that penetrate membranes, is more efficient than the mechanism of hydroxycinnamic acids
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Salvagnini, Claudio. "Thrombin inhibitors grafting on polyester membranes for the preparation of blood-compatible materials." Université catholique de Louvain, 2005. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-11232005-103604/.
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The design of biomaterials, historically initiated and developed by physicians and engineers, in the last decades has slowly shifted toward a more biochemical based approach. For the replacement, repair and regeneration of tissues scientists are now focusing on materials that stimulate specific biological response at the molecular level. These biomaterials have already shown interesting applications in cell proliferation, differentiation, and extracellular matrix production and organization when the material modifications are designed to elicit specific interactions with cell integrins. In the present work we propose the application of this strategy for the development of blood-compatible materials. We first identified, in the coagulation cascade a key enzyme that constitute a valuable biological target for the development of anti-thrombogenic compounds. Piperazinyl-amide derivatives of N-alfa-(3-trifluoromethyl-benzenesulfonyl)-L-arginine were synthesized as graftable thrombin inhibitors. These inhibitors provided a spacer arm for surface grafting and a fluorine tag for XPS (X-ray photoelectron spectroscopy) detection. The possible disturbance of biological activity due to a variable spacer-arm fixed on the N-4 piperazinyl position was evaluated in vitro against human alfa-thrombin, in silico by molecular modelling and via X-ray diffraction study. Selected inhibitors, having inhibition potency in the mM range, were grafted on polyesters surface via wet chemistry and photochemical activation treatments. Wet chemistry surface grafting was performed by specific hydroxyl chain-ends activation and resulted in bioactive molecules fixation of 20-300pmol/cm2. The photochemical grafting was performed using a molecular clip providing an aromatic azide, for nitrene insertion into a polymer, and an activated ester for grafting of tag compounds. This grafting technique resulted in a dramatic increase in fixed bioactive signals (up to nmol/cm2). The material blood-compatibilization induced by the surface fixation of the inhibitors, was measured by a static blood clot weight measurement test. The wet chemistry grafting technique resulted in moderate blood-compatibilization while by the photochemical grafting method important decrease in surface blood clot formation was observed. In the latter case, the blood response to material contact was found to be strongly affected by the polyester surface photo-degradation induced by the activation treatment.
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Hertig, Alexandre. "Rôle de l'inhibiteur de type 1 des activateurs du plasminogène dans la régulation de la fibrinolyse glomérulaire : application au modèle de glomérulonéphrite par anticorps anti-membrane basale glomérulaire." Paris 6, 2004. http://www.theses.fr/2004PA066590.
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Silva, Mojica Ernesto. "Polymer-silica Hybrids for Separation of CO2 and Catalysis of Organic Reactions." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1398439043.
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AinurRosidah, Afira, and 羅海誼. "Functionalized Carbon Nanofiber/PBI Nanocomposite Membranes for High Temperature Proton Exchange Membrane Fuel Cells." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6x47ry.
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Wang, Chun-Ju, and 王俊茹. "The separation of PBI based on molecular weight&The effect of molecular weight upon PBI membrane properties." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/91944167594103797582.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>98<br>The effect of molecular weight upon polybenzimidazole (PBI) membrane properties has been investigated. PBI was synthesized by polymerization of 3,3-diaminobenzidine and isophthalic acid with a molar ratio of 1:1. The structure of PBI was determined by FTIR. The obtained polymer was then fractionated by dissolving in various solvent at temperatures 30◦C The weight-averaged molecular weights of 1.24×104, 8.85×104, 2.91×105, and 3.81×105 g /mol were obtained. PBI membranes have been prepared with different molecular weights. The acid uptake and mechanical strength were studied for the pristine PBI membranes and PBI membranes before and after being doped with phosphoric acid. The acid doping level of PBI membrane was increased with increasing the molecular weight PBI. High molecular weights of the PBI membrane improve the mechanical strength. After being doped with phosphoric acid, the mechanical strength of the membranes became poor.
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Yi-KuangChen and 陳宜寬. "Effects of Reformate on PBI/H3PO4 Proton Exchange Membrane Fuel Cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/13745068525017325226.
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碩士<br>國立成功大學<br>航空太空工程學系碩博士班<br>100<br>The reformate gas produced from a reformer has to be purified in order to reduce the carbon monoxide concentration to a range which is tolerable for a proton exchange membrane fuel cell. One of the key points to break through the limit of the carbon monoxide tolerance is the operation temperature of the fuel cell. Thus, a high temperature proton exchange membrane fuel cell is developed to improve the carbon monoxide tolerance and to simplify the gas purification process. The polybenzimidazole-based phosphoric acid-doped fuel cell is one of the most promising systems for a high temperature proton exchange membrane fuel cell.
In this study, a self-made gas mixer is used to supply simulated reformate gases with different hydrogen and carbon monoxide concentrations into the fuel cell. The polarization curve, the long term galvanostatic analysis and the electrochemical impedance spectroscopy are used to analyze the performance and the impedance of a high temperature proton exchange membrane fuel cell. The parameters include the operational temperature, carbon monoxide concentration and the hydrogen concentration respectively. The experimental results show that the carbon monoxide tolerance of a polybenzimidazole-based phosphoric acid-doped fuel cell increases with increasing the operational temperature. In addition, effects of carbon monoxide on the fuel cell performance and the impedance become more significant while decreasing the hydrogen concentration. On the other hand, a low hydrogen concentration（50%） and a high carbon monoxide（3%） concentration may result in a dangerous low voltage a voltage fluctuation.
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Wen, Chia-Hao, and 温佳豪. "Preparation of Pt/PyPBI-CNT catalysts and modification PBI membranes for high temperature proton exchange membrane fuel cells." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/cqq83f.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>106<br>In order to combine fuel cell with methanol reformer, we prepared the membrane electrode assembly (MEA) which operation temperature close to the methanol reformer in this study. MEAs were prepared by grafting PSi-EP with H3PO4 proton exchange membrane and the catalyst was Pt/PyPBI-CNT which prepared by immobilizing platinum (Pt) nanoparticles on the surface of the PyPBI wrapped MWCNTs (PyPBI-CNTs). Cathodes were prepared by mixing Pt/PyPBI-CNT powder, binder, and solvent. Binder were the mixtures of polybenzimidazole (PBI) in the weight ratio of 0/5,1/4, and 2/3, respectively.
Among the binders, the binder in the weight ratio of 1/4 exhibited the best fuel cell performance and excellent durability during 24 h operation with unhumidified H2/O2 gases. Compared with the binder in the weight ratio of 1/4, the increase of binder content result in the increase of H3PO4 content in catalyst layer and decrease the performance of unit cell for binder in the weight ratio of 2/3. As a consequence, optimum amount of binder in catalyst layer will enhance the performance and durability of HT-PMFC.
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Lin, Jin-Yung, and 林靖詠. "Preparation of PBI catalyst layers for high-temperature proton exchange membrane fuel cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/84658349858719588701.
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碩士<br>元智大學<br>機械工程學系<br>98<br>Nafion in the low temperature proton exchange membrane (PEM) fuel cell can conducted proton with moderate moisture content, therefore when in the low humidity and high operation temperature up to 90℃ the membrane conductivity will decrease due to the water evaporation. In this study, we use the high polymer material polybenzimidazole (PBI) as a proton exchange membrane for high temperature PEMFC. PBI has good thermal stability, high anti-chemical corrosion ability and high glass transition temperature. PBI was used as the binder in the catalyst layers the membrane electrode assembly (MEA). In this research, we investigated the influence of the PBI/(PBI+Pt-C) wt ratio (where Pt-C is the carbon supported Pt catalyst with a 40wt% Pt content) on the catalyst activity and fuel cell performance.Our experimental data show the optimum wt ratio of PBI in catalyst layer is ~5wt%. As the PEMFC performance decreases after 8 hours continuous operation, a modified catalyst layer structure with gradient increasing PBI content in catalyst layer from gas diffusion layer (GDL) to PEM is investigated. Experimental results show the three-layer structure catalyst layer with gradient increment of PBI content in catalyst layer from GDL to the membrane by 5 wt%、10 wt%、20 wt%. has a better PEMFC performance than the conventional catalyst layer and the fuel cell performance does not decrease after 8hr continuous operation.
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Cheng, Kuo-yao, and 鄭國曜. "Effects of Reformate on Performance of PBI/H3PO4 Proton Exchange Membrane Fuel Cell Stack." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75661595700715922966.
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碩士<br>國立臺南大學<br>綠色能源科技研究所碩士班<br>101<br>In this study, the performance of a five-cell fuel cell stack performance by changing the nitrogen and carbon dioxide concentration was examined experimentally. The hydrogen concentration in the reformer gas is not the same and stable, some of them may have some poison gases which like carbon dioxide. The poison gases make the performance of fuel cells decay. For examining the performance variation, the polarization curve and EIS (electrochemical impedance spectroscopy) methods were presented in this study. The best operating temperature of fuel cell stack is 160 ˚C. It is found that there is no obvious effect on cell performance and impedance when the stoichiometry of the gas in anode was changed. But the cell performance becomes better and the impedance becomes lower for the case with a higher stoichiometricy of cathode gas. The higher percentage of nitrogen makes hydrogen dilute and make the cell performance to be decreased. When carbon dioxide exceeds 3%, the pt-catalyst was covered with the CO and the cell performance decreases. When the carbon dioxide was over 5%, the decay of the cell performance becomes stable. Additionally, the higher operating stack temperature has greater poison tolerance.
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Lin, Wan-Sin, and 林婉歆. "Pt-C/PBI/DMAc solutions properties and preparation of membrane electrode assemblies for high temperature PEMFCs." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/22060763981605125791.
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碩士<br>元智大學<br>先進能源研究所<br>98<br>In this study, using static light scattering (SLS), gel permeation chromatography (GPC) and cyclic voltammetry(CV), we reported the dilute solutions properties of polybenzimidazole (PBI) in N,N’-dimethylacetamide (DMAc) solutions blended with LiCl and preparation of Pt-C/PBI membrane electrodes assemblies for high temperature fuel cells. Our GPC experimental results showed weight-average molecular weight (Mw) is 1.13×105 g/mol (PBI-113) and 2.53×105 g/mol (PBI-253) of PBIs synthesiszed in our lab. An ultrasonic coating made of electrode catalyst slurry solution, a cyclic voltammetry (CV) was used to study the electrochemical properties of electrodes prepared form various Pt-C/PBI/DMAc/LiCl solutions. We found the ekectrode prepated from Pt-C/PBI/DMAc/LiCl solution with a [LiCl]/[PBI] wt ratio of 1/1 and a [PBI] / [Pt-C + PBI] wt ratio of 10 wt% had a higher Pt surface activity area. The 160℃PEMFC unit cell test showed the membrane electrode assembly (MEA) prepared from a PBI with catalyst layes prepared a solution consisting of [PBI]/[Pt-C+PBI] = 5 wt% and [LiCl]/[PBI] = 1/1 by wt had a best fuel cell performance. The 228 hr long time continuous PEMFC unit cell test had been carried out at 160℃ and I = 200 mA/cm2. The experimental result showed a voltage decay rated of ~1.34×10-4 V/hr.
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CHEN, WEI-CHENG, and 陳韋成. "High temperature PEM fuel cells and its PBI membrane doped with phosphoric acid and antimony chloride." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/24216054053970045614.
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碩士<br>國立臺灣科技大學<br>化學工程系<br>101<br>In recent years, the high-temperature proton exchange membrane (PEM) fuel cells have been developed to operate at 160 – 200?aC, such that its carbon monoxide tolerance can be improved and the fuel flexibility can be enhanced. Most of research efforts are focused on the membrane of phosphoric acid doped polybenzimidazole (PBI) and its variants. For those PEM fuel cells based on phosphoric acid doped PBI, the operation temperature is usually set at 160?aC. Adoption of a hybrid organic- inorganic PBI membrane could further raise the operation temperature and enhance the fuel flexibility. In this study, we infiltrate the PBI membrane with antimony chloride and phosphoric acid sequentially and obtain the hybrid organic-inorganic PBI membrane, which exhibits stable ion conductivity in the temperature range of 180-260?aC, with the maximum ion conductivity of 8.08?e10-2 S cm-1 at 180?aC. In contrast, the phosphoric acid doped PBI membrane displays its maximum conductivity of 1.2×10-2 S cm-1 at 160?aC.
The PEM fuel cell based on a hybrid PBI membrane outperforms the PEM fuel cell of phosphoric acid doped PBI membrane in power and stability. The peak power value of the former measures 512 mW/cm2, higher than that of the latter 388 mW/cm2. These peak power values are obtained after the activation process, which is executed in constant current mode at 0.2 mA cm-2 for 12 h. Activation process reduces the membrane resistance through generating water in the system. We further verify the carbon monoxide tolerance of the PEM fuel cell of hybrid PBI membrane in an alternating-fuel schedule, in which the pure hydrogen and the hydrogen containing 3% CO alternatively feed in the anode side for 1 h. The voltage at 0.1 mA cm-2 and 180?aC displays a significant drop in the first feed containing CO, but recover to its original value after the second feed containing CO.
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Pan, Chih-Hsuan, and 潘芷萱. "Characteristics of PBI and PTFE binder in catalyst layer for high temperature proton exchange membrane fuel cells." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/csfwuj.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>106<br>The effects of PTFE and PBI binder properties on cell performance were investigated for high temperature proton exchange membrane fuel cell (PEMFC) in this study. PBI-epoxy membranes were used for MEA preparation. The performance of these MEAs was evaluated by accelerated aging test. However, several related measurements were conducted before and after ageing test at 160°C, 0 % RH to examine the change of characteristics of MEA components. The resulting electrodes and membrane were characterized by contact angle, thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), and scanning electron microscope/ energy dispersive spectrometer (SEM/ EDS).
TGA analysis showed that the thermal stability of PBI-epoxy membrane does not change significant after ageing tests. XRD Images of Pt/C showed coalescence and sintering of Pt nanoparticles after ageing test. The increase of Pt2+ and Pt4+ content was observed from XPS results. Pt band inside the membrane was observed by SEM/EDS analyses, which is due to dissolved platinum into the membrane and recrystallize by interacting with the crossover hydrogen. Finally, it was found that the electrodes with PTFE binder showed the better performance and durability than those with PBI binder.
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Liu, Shih-Hao, and 劉士豪. "Prepareation of Nafion/PBI electro-spun fiber composite membrane and it''s application to fuel cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/34322973203700083649.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>98<br>This study report the influence of polymerization time on the molecular weight of PBI (polybenzimidazole). The PBI with Mw of ~
1.0×105 g/mol was mixed with DMAc (N,N’-dimethylacetamide) solvent and electrospun from the solution. The PBI electrospun nano-fiber film was crosslinked with glutaraldehyde. The tensile strength of the PBI nano-fiber film was around 37.2MPa. The high mechanical strength PBI nano-fiber film was then immersed in a Nafion solution to prepare Nafion/PBI-fiber composite membranes with a thickness of around 35 ?m. The power density of the membrane electrode assembly (MEA) prepared form the composite membrane was arind 793 mW/cm2 which was higher than that prepared from Nafion-212 (thickness~50 ?m; power density~ 508 mW/cm2).
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Hofmann, Constanze. "Untersuchungen zur Elektrokatalyse von Hochtemperatur-Polymerelektrolytmembran-Brennstoffzellen (HT-PEMFCs)." Doctoral thesis, 2010. http://hdl.handle.net/11858/00-1735-0000-0006-B06B-9.
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Krüger, Andries Johannes. "Evaluation of process parameters and membranes for SO2 electrolysis / Andries Johannes Krüger." Thesis, 2015. http://hdl.handle.net/10394/16022.
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The environmentally unsafe by-products (CO2, H2S, NOx and SO2 for example) of using carbon-based fuels for energy generation have paved the way for research on cleaner, renewable and possibly cheaper alternative energy production methods. Hydrogen gas, which is considered as an energy carrier, can be applied in a fuel cell setup for the production of electrical energy. Although various methods of hydrogen production are available, sulphur-based thermochemical processes (such as the Hybrid Sulfur Process (HyS)) are favoured as alternative options for large scale application. The SO2 electrolyser is applied in producing H2 gas and H2SO4 by electrochemically converting SO2 gas and water. This study focused firstly on the evaluation of the performance of the SO2 electrolyser for the production of hydrogen and sulphuric acid, using commercially available PFSA (perfluorosulfonic acid) (Nafion®) as benchmark by evaluating i) various operating parameters (such as cell temperature and membrane thickness), ii) the influence of MEA (membrane electrode assembly) manufacturing parameters (hot pressing time and pressure) and iii) the effect of H2S as a contaminant. Subsequently, the suitability of novel PBI polyaromatic blend membranes was evaluated for application in an SO2 electrolyser.
The parametric study revealed that, depending on the desired operating voltage and acid concentration, the optimisation of the operating conditions was critical. An increased cell temperature promoted both cell voltage and acid concentration while the use of thin membranes resulted in a reduced voltage and acid concentration. While an increased catalyst loading resulted in increased cell efficiency, such increase would result in an increase in manufacturing costs. Using electrochemical impedance spectroscopy at the optimised operating conditions, the MEA manufacturing process was optimised with respect to hot press pressure and time, while the effect of selected operating conditions was used to evaluate the charge transfer resistance, ohmic resistance and mass transport limitations. Results showed that the optimal hot pressing conditions were 125 kg.cm-2 and 50 kg.cm-2 for 5 minutes when using 25 and 10 cm2 active areas, respectively. The charge transfer resistance and mass transport were mostly influenced by the hot pressing procedure, while the ohmic resistance varied most with temperature.
Applying the SO2 electrolyser in an alternative environment to the HyS thermochemical cycle, the effect of H2S on the SO2 electrolyser anode was investigated for the possible use of SO2 electrolysis to remove SO2 from mining off-gas which could contain H2S. Polarisation curves, EIS and CO stripping were used to evaluate the transient voltage response of various H2S levels (ppm) on cell efficiency. EIS confirmed that the charge transfer resistance increased as the H2S competed with the SO2 for active catalyst sites. Mass transport limitations were observed at high H2S levels (80 ppm) while the ECSA (electrochemical surface area obtained by CO stripping) showed a significant reduction of active catalyst sites due to the presence of H2S. Pure SO2 reduced the effective active area by 89% (which is desired in this case) while the presence of 80 ppm H2S reduced the active catalyst area to 85%.
The suitability of PBI-based blend membranes in the SO2 electrolyser was evaluated by using chemical stability tests and electrochemical MEA characterisation. F6PBI was used as the PBI-containing base excess polymer which was blended with either partially fluorinated aromatic polyether (sFS001), poly(2,6-dimethylbromide-1,4-phenylene oxide (PPOBr) or poly(tetrafluorostyrene-4-phosphonic acid) (PWN) in various ratios. Some of the blend membranes also contained a cross-linking agent which was specifically added in an attempt to reduce swelling and promote cross-linking within the polymer matrix. The chemical stability of the blended membranes was confirmed by using weight and swelling changes, TGA-FTIR and TGA-MS. All membranes tested showed low to no chemical degradation when exposed to 80 wt% H2SO4 at 80°C for 120 h. Once the MEA doping procedure had been optimised, electrochemical characterisation of the PBI MEAs, including polarisation curves, voltage stepping and long term operation (> 24 h) was used to evaluate the MEAs. Although performance degradation was observed for the PBI membranes during voltage stepping, it was shown that this characterisation technique could be applied with relative ease, producing valuable insights into MEA stability. Since it is expected that the SO2 electrolyser will be operated under static conditions (cell temperature, pressure and current density) in an industrial setting (HyS cycle or for SO2 removal), a long term study was included. Operating the SO2 electrolyser under constant current density of 0.1 A cm-2 confirmed that PBI-based polyaromatic membranes were suitable, if not preferred, for the SO2 environment, showing stable performance for 170 hours.
This work evaluated the performance of commercial materials while further adding insights into both characterisation techniques for chemical stability of polymer materials and electrochemical methods for MEA evaluation to current published literature. In addition to the characterisation techniques this study also provides ample support for the use of PBI-based materials in the SO2 electrolyser.<br>PhD (Chemistry), North-West University, Potchefstroom Campus, 2015
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Wang, Wei-Sheng, and 王韋勝. "Nafion/PBI membranes for DMFCs." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/73295268481148879555.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>99<br>On this thesis, we prepare Nafion/PBI blend membranes and study their mechanical properties, proton conductivities, methanol permeateon and the application to direct methanol fuel cell (DMFC). We find the membrane with a Nafion/PBI wt ratio of 9/1 has a optimum property. The Nafion/PBI blend (9/1 g/g) with a thichness of 78 μm is used to prepare MEA and performed DMFC test. The experiment results show that the present membrane had a better DMFC performance than Nafion-117.
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Chang, Wei-kai, and 張維凱. "Preparations of PBI Membranes and PBI-PTFE composite membranes and their applications to fuel cells." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/68605430220064241329.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>94<br>In this thesis PBI membranes (thickness 60~200 μm) were prepared by casting from LiCl / DMAc solutions, and PBI-PTFE composite membranes (20~36 μm thickness) were prepare by impregnating porous PTFE (poly tetrafluoroethylene) in PBI / LiCl / DMAc solutions. Both of these two membranes were than impregnating with phosphoric acid solution and were used to prepare membrane electrolyte assembly (MEA). Though PTFE has a lower conductivity than PBI, however, the high mechanical strength of PTFE allow the PBI-PTFE composite membranes to have a lower thickness when they were used in full cells applications. The lower thickness (20~36 μm) of PBI-PTFE composite membranes caused than to have lower resistance than PBI (60~200 μm) membranes. In this study, we showed that PBI-PTFE composite membranes had better PEMFC performance than Nafion117 and PBI at 70℃, and also PBI-PTFE composite membrane had better PEMFC performance than PBI at 180℃.
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Lin, Che-Yu, and 林哲宇. "Preparation and Performance Study of PBI/PBI-BS/Zr(HPO4)2 Composite Membranes." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/92564416675614308464.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>96<br>In this thesis, polybenzimidazole (PBI) membrane was modified with sulfobutylated polybenzimidazole (PBI-BS) and zirconium phosphate (Zr(HPO4)2). The influences of Zr(HPO4)2 and PBI-BS on PBI PEMFC performance at 140~180℃ was investigated in this work. The chemical structures of PBI and PBI-BS were identified by FTIR spectrometer. The morphology of surface and cross section of the membrances was observed by SEM (Scanning Electron Microscope), and EDS (Energy Dispersive Spectrometer). TGA (thermogravimetric analysis) was used to carry out thermo properties of membranes. The membranes were fabricated with the catalyst layers to prepare MEA and carried out single cell tests.
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Liao, Jen-Ru, and 廖貞如. "Preparation and High Temperature Fuel Cell Performance of PBI/PBI-BS Blend Membranes." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/33252514867127464176.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>97<br>In this thesis, we synthesized polybenzimidazole (PBI) and its derivative butyl sulfonated poly(polybenzimidazole) (PBI-BS). PBI/PBI-BS blend membranes were prepared with a PBI/PBI-BS wt ratio of 8/2. The chemical structure and physical properties of the membrane were investigated, using FTIR, SEM, EDS, and TGA. 400 h continuous stability life test and 298 h start/stop cycle test (10 h/start – 14 h/stop) on the MEA prepared from phosphoric acid-doped PBI/PBI-BS were conducted at 160℃with a current density= 200 mAcm−2. i-V polarization curve and AC-impedance test of MEA were performed every 12 h in the long time life test and each cycle in the start/stop cycle test. The data of 400 h life test showed decay of cell voltage V around 17% and the increments of resistance of membrane and electrolyte with increasing test time. The low pH value of the water collected from cathode outlet migration of H3PO4 from MEA. The 298 h start/stop cycle test showed no significant change of cell voltage V and membrane resistance, but increment of charge transfer of catalyst layer. The low pH value of water was also collected from cathode outlet during the start/stop cycle test. This result also indicates migration of H3PO4 during start/stop cycle test.
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Hsieh, Yi-Shan, and 謝依珊. "Preparations and Performance Studies of PBI/PTFE andPBI/PBI-BS/PTFE Composite Membranes." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/11078163668215140178.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>97<br>In this study, we synthesized polybenzimidazole (PBI) and its derivative butyl sulfonated polybenzimidazle (PBI-BS).The porous poly tetra fluoro ethylene (PTFE) was used as supporting membranes to reinforce PBI and PBI/PBI-BS (8/2 g/g) blend to prepare PBI/PTFE and PBI/PBI-BS/PTFE composite membranes. These two composite membranes were used to prepare membrane electrode assemblies (MEA). We performed 400 hr H2/O2 life test on PBI/PTFE MEA and 100 hr test on PBI/PBI-BS/PTFE MEA at 160 ℃ with a current density
i = 200 mA/cm2. During long time life test, the i-V curve and AC-impedance measurements of MEAs were performed every 12 hr.
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Davies, Benjamin. "Separation of CO2 using ultra-thin multi-layer polymeric membranes for compartmentalized fiber optic sensor applications." Thesis, 2014. http://hdl.handle.net/1828/5207.
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Carbon dioxide sequestration is one of many mitigation tools available to help reduce carbon dioxide emissions while other disposal/repurposing methods are being investigated. Geologic sequestration is the most stable option for long-term storage of carbon dioxide (CO2), with significant CO2 trapping occurring through mineralization within the first 20-50 years. A fiber optic based monitoring system has been proposed to provide real time concentrations of CO2 at various points throughout the geologic formation. The proposed sensor is sensitive to the refractive index (RI) of substances in direct contact with the sensing component. As RI is a measurement of light propagating through a bulk medium relative to light propagating through a vacuum, the extraction of the effects of any specific component of that medium to the RI remains very difficult. Therefore, a requirement for a selective barrier to be able to prevent confounding substances from being in contact with the sensor and specifically isolate CO2 is necessary. As such a method to evaluate the performance of the selective element of the sensor was investigated. Polybenzimidazole (PBI) and VTEC polyimide (PI) 1388 are high performance polymers with good selectivity for CO2 used in high temperature gas separations. These polymers were spin coated onto a glass substrate and cured to form ultra-thin (>10 μm) membranes for gas separation. At a range of pressures (0.14 –0.41 MPa) and a set temperature of 24.2±0.8 °C, intrinsic permeabilities to CO2 and nitrogen (N2) were investigated as they are the gases of highest prevalence in underground aquifers. Preliminary RI testing for proof of concept has yielded promising results when the sensor is exposed exclusively to CO2 or N2. However, the use of both PBI and VTEC PI in these trials resulted in CO2 selectivities of 0.72 to 0.87 and 0.33 to 0.63 respectively, for corresponding feed pressures of 0.14 to 0.41 MPa. This indicates that both of the polymers are more selective for N2 and should not be used in CO2 sensing applications as confounding gas permeants, specifically N2, will interfere with the sensing element.<br>Graduate<br>0428<br>0495<br>0542<br>ben.t.davies@gmail.com
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Chou, Yu-Cheng, and 周祐成. "PBI crosslinked membranes-preparation and applications to PEMFC." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/25281257228284410116.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>98<br>In this thesis, we synthesized polybenzimidazole (PBI) from 3,3’-diaminobenzidine and isophthalic acid. The molecular weight of PBI determined by GPC (gel permeation chromatography) with polystyrene as a standard was Mw = 2×105 g/mol. The crosslinked PBI was prepared by blending PBI with epoxy (Epon-828) resin with a N-H/epoxide equivalent ratio of 10/1. The tensile strength of PBI/epoxy crosslinked membrane was around 20％ higher than that of pure PBI , which allows the thickness of PBI/epoxy membrane (thickness ~ 45 μm) to be lower than that of PBI membrane when they were used as proton exchange membrane (PEM) of fuel cells. We showed the PBI/epoxy membrane (thickness ~ 45 μm) had a better PEMFC (proton exchange membrane fuel cell) performance than pure PBI membrane (thickness ~ 80 μm) at 160 ℃. The long time 300 hr test at 160 ℃was operated at a current density i = 200 mA/cm2 , which showed a decay rate of 2×10-4 V/hr . The cyclic voltammetry (CV) and impedance test showed the resistance of catalyst (Rc) increased after 300 hr fuel cell test . The SEM and EDS analyses also revealed agglomeration of Pt particles at cathode after 300 hr fuel cell test .
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Tsai, Ming-Chih, and 蔡明志. "Investigation on microstructure of phosphoric acid doped PBI membranes." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/hp79u2.
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碩士<br>國立臺灣科技大學<br>材料科學與工程系<br>104<br>Recently, there has been great interest in developing polybenzimidazole (PBI) membranes for high temperature Proton Exchange Membrane Fuel Cell (PEMFC). Research on PBI membranes for high-temp PEMFC has encounter many problems, such as high solubility of PBI, Pt poisoning and low proton conductivity. Herein, we prepared pata-polybenzimidazole membranes (p-PBI) by sol-gel method and compared it with commercially available meta-polybenzimidazole membrane (m-PBI) which was prepared by solution casting method. p-PBI with an acid doping level(ADL) of 10 PA/RU showed proton conductivity of 0.208 S cm-1 which is twice higher than that of commercial m-PBI with the same acid doping level (0.11 S cm-1). Their properties were found to be dependent on their polymer structure as well as the membrane morphology. Microstructures of PBI membranes have been studied by AFM, conductive AFM, EDS and TEM. p-PBI prepared by sol-gel method with ADL=10 PA/RU showed well connected ion channel with size about 70 nm which is larger than that of commercial m-PBI (50 nm). In the fuel cell test, p-PBI membrane prepared by sol-gel method with an acid doping level(ADL) of 10 PA/RU showed peak power density of 1050 mW cm-2, which is twice higher than that of solution casting m-PBI membrane with the same acid doping level (570 mW cm-2). This indicates that, in addition to ADL, microstructure of membranes plays a very important role on the proton conductivity and fuel cell performance. Their morphological images observed by AFM, C-AFM and TEM show the existence of ionic channels, which can be good indication for proton conductivity of the membranes.
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Liu, Yu-Chi, and 劉宥琪. "Preparation of PBI/PPA Membranes for High Temperature PEMFCs." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/19351551466367518099.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>99<br>In this thesis, we synthesized polybenzimidazole (PBI) from 3,3’-diaminobenzidine and isophthalic acid . The molecular weight of PBI determined by GPC (gel permeation chromatography) with polystyrene as a standard was Mw = 2.05×105 g/mol. The polymerized find product mixture PBI with PPA was used to prepare the proton exchange membrane. The morphology of surface and cross section of the membrances was investigated using by SEM (Scanning Electron Microscope). TGA (thermogravimetric analysis) was used to study the thermo properties of membranes. The membranes were fabricated with the catalyst layers to prepare MEAs and carried out single cell tests.
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Huang, Jun-Ru, and 黃俊儒. "PBI-PTFE Composite Membranes Preparation and Applications to Fuel Cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66773974820467195044.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>98<br>In this study, the porous (polytetra fluoro ethylene) (PTFE) was used as a supporting membrane and immersed in a polybenzimidazole(PBI)/n, n’-dimethyl acetamide(DMAc) solution to prepare PBI/PTFE composite membranes. These crosslinked composite membrane was used to prepare membrane electrode assemblies (MEA). We performed 300 hr H2/O2 life test on PBI/PTFE MEA at 160℃ at a current density i = 200 mA/cm2. During long time life test, the i-V curve measurement was performed every 12 hr.
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Tang, Tsung-Hsien, and 湯宗弦. "PBI grafted side chain phosphate membranes for high-temperature PEMFCs." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/27148251143471699884.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>99<br>本研究合成聚苯並咪唑(PBI)和接枝磷酸支鏈的苯甲基磷酸聚苯並咪唑(PBI-BPA)，利用FTIR、NMR及GPC進行結構分析及分子量測定。以PBI/PBI-BPA製備摻合膜並浸漬磷酸。磷酸含酸率測定顯示PBI-BPA摻合重量比例增加，膜材含磷酸率增加，但PBI-BPA比例超過40%以上膜材會完全被磷酸溶解。160℃質子交換膜燃料電池單電池性能測試顯示，PBI/PBI-BPA (重量比8 : 2) MEA具有良好的電池性能。電池在540小時開關循環測試中，開機性能在cycle 11 (t = 240 h)達到最佳，cycle 16 (t = 360 h)時性能衰退至最低。交流阻抗分析顯示觸媒阻抗上升是造成電池性能衰退的主因。循環伏安(CV)數據顯示電極中觸媒活性面積下降。
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Shen, Shih-Yuan, and 沈詩源. "PBI-PPA/PTFE composite membranes preparation and applications to fuel cells." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/70742759067911549632.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>99<br>In this study, we synthesize polybenzimidazole (PBI) from isophthalic acid and 3,3’-diaminobenzidine monomers using polyphosphoric acid (PPA) as a solvent. The polymer structures and molecular weight are investigated using FTIR spectroscopy and GPC. The porous polytetrafluoroethylene (PTFE) is used as a supporting membranes to reinforce the polymerized PBI–PPA blend and prepare PBI-PPA/PTFE composite membrane (thickness 40-55 µm). The PBI-PPA/PTFE composite membranes have been fabricated for 160 ℃high temperature proton exchange membrane fuel cells. PBI-PPA-963/PTFE composite membrane has a best performance of the max power density of 366 mW/cm2.
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Wang, Ming-Tsung, and 王明琮. "PBI/SPEEK and Nafion/PAN nanofiber composite membranes－Preparation and applications to fuel cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/54100288225266849149.
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碩士<br>元智大學<br>化學工程與材料科學學系<br>98<br>In this study, we use electro-spinning technology to make two series of proton exchange composite membranes. PEEK (polyether ether ketone) was modified by slufonation, nitration and reduction. The SPEEK-NH2 nanof-fiber thin film was prepared by electro-spinning from a SPEEK-NH2/DMAc (N,N,-dimethyl acetamide) solution. The electro-spin SPEEK-NH2 nono-fiber film was then treated with glutaraldehyde to proceed crosslink reaction. Crosslinked SPEEK-NH2 film was then impregnated in PBI/DMAc solution and heated under 120℃ to make PBI/SPEEK composite membrane. From TGA testing we found that the membrane was thermal stable below 200℃, and the membrane can be used in PEMFC (proton exchange membrane fuel cell).
The widely used proton exchange membrane in DMFC (direct methanol fuel cell) is Nafion-117. The membrane has problems with high methanol permeability and high thickness (175 μm). Nafion/PAN composite proton exchange membrane was prepared by impregnating PAN (polyacrylonitrile) nanofiber film with Nafion/isopropanol solution. Nafion/PAN composite membrane had a thickness about 60 μm and a lower methanol permeability than Nafion-117. We shows that Nafion/PAN composite membrane had a similar DMFC performance to Nafion-117.
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"Evaluation of PCI reverse osmosis membrane on landfill leachate." Thesis, 2010. http://hdl.handle.net/10413/1447.
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Yu, Bor Chern, and 余柏辰. "Preparation of PBI/Graphene Oxide Composite Membranes by Spin Coating Method for Alkaline Direct Alcohol Fuel Cells." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/g848gh.
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Yu, Hsin-Han, and 尤信翰. "A study of Frame, Membrane, Solid,Shell, Spring and Cable elementsusing Vector Form Intrinsic Finite Element Method in PNS-PBC framework." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/10172079400950904385.
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碩士<br>中原大學<br>土木工程研究所<br>100<br>Abstract
The main purpose of this study is to add some functions for different types of the elements into the Platform for Numerical Simulation - Point Based Computing ( PNS-PBC ) framework. This framework is developed from the National Center for Research on Earthquake Engineering (NCREE) in 2011. The PNS-PBC is based on two methods which are vector form intrinsic finite element (VFIFE or V-5) method and discrete element method (DEM). In this study, the formulations of the shell, cable, spring, 4 point solid, Euler beam, Timoshenko beam in VFIFE method are implemented in PNS-PBC. Firstly, the internal forces of the Timoshenko beam, cable, and spring for VFIFE method are derived in this study. In order to prove the accuracy for deformation of the elements, the rotation tests and numerical simulations using ANSYS are compared with the numerical simulations using VFIFE method. It is confirmed the good accuracy of the VFIFE method.
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Βόγλη, Ευφροσύνη. "Συγκριτική μελέτη πρωτονίωσης / εμποτισμού πολυμερικών ηλεκτρολυτικών μεμβρανών για στοιχεία καυσίμου υψηλής θερμοκρασίας". Thesis, 2009. http://nemertes.lis.upatras.gr/jspui/handle/10889/1629.
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Η συγκεκριμένη διατριβή ειδίκευσης αποτελεί μια προσπάθεια συγκριτικής μελέτης νέων πολυμερικών ηλεκτρολυτικών μεμβρανών για στοιχεία καύσιμου υψηλής θερμοκρασίας, με το PBI (πολυβενζιμιδαζόλιο).
Αρχικά πραγματοποιήθηκε μια φασματοσκοπική και ηλεκτροχημική μελέτη των μεμβρανών. Πιο συγκεκριμένα μελετήθηκαν η μεμβράνη ADVENT TPS® και τα μίγματα SFSX-PBIY (σουλφονωμένο δεκαφλουοροδιφαινύλιο με εξαφλουοροισοπροπυλενό- διφαινολη - πολυβενζιμιδαζόλιο) εμποτισμένα με πυκνό διάλυμα φωσφορικού οξέος 85%. Η ηλεκτροχημική μελέτη αφορούσε τη μέτρηση της ιοντικής αγωγιμότητας συναρτήσει του βαθμού εμποτισμού, ενώ η φασματοσκοπική μελέτη πραγματοποιήθηκε με τη χρήση δονητικής φασματοσκοπίας FT-IR και FT-Raman επίσης συναρτήσει του βαθμού εμποτισμού, κάνοντας έτσι δυνατή τη συσχέτιση των δονητικών φασμάτων με την ιοντική αγωγιμότητα.
Με τη φασματοσκοπία FT-Raman μελετήθηκε το φαινόμενο της πρωτονίωσης των μεμβρανών με το φωσφορικό οξύ. Η συσχέτιση του βαθμού εμποτισμού με τις σχετικές εντάσεις συγκεκριμένων κορυφών (1589 cm-1 και 1632 cm-1 για το TPS και 1593 cm-1 και 1570 cm-1 για τα μίγματα SFSX-PBIY) δίνει την δυνατότητα υπολογισμού των μορίων φωσφορικού οξέος που απαιτούνται για να πρωτονιώσουν έναν πυριδινικό δακτύλιο στην πρώτη περίπτωση και δυο ιμιδαζολικούς δακτυλίους στην δεύτερη.
Το δεύτερο μέρος της μελέτης αφορούσε την εξέταση του φαινομένου αποβολής του εμποτίζοντος μέσου από την μεμβράνη, γεγονός που αποτελεί το κυριότερο πρόβλημα μη εμπορικής διαθεσιμότητας κυψελίδων καυσίμου αγωγής πρωτονίων μέσω ηλεκτρολυτικής πολυμερικής μεμβράνης υψηλών θερμοκρασιών.
Μέσω φασματοσκοπίας FT-Raman παρακολουθούμε τη διαδικασία της πλήρους πρωτονίωσης των μεμβρανών που είναι προαπαιτούμενο για τον περαιτέρω εμποτισμό τους. Στη συνέχεια ακολουθεί η διαδικασία σταθεροποίησης τους υπό θέρμανση και υπό θέρμανση και πίεση ταυτόχρονα σε διαφορετικές θερμοκρασίες, που μας επιτρέπει να υπολογίσουμε τα μόρια του εμποτίζοντος μέσου που συγκρατεί τελικά η μεμβράνη και την ποιοτική τους κατάσταση στο τέλος της διαδικασίας.<br>Proton exchange membrane fuel cells (PEMFCs) have gained international attention as candidates for alternative automobile and stationary power sources. The electrolyte is a polymeric membrane. Poly(benzimidazole), PBI, has been widely studied with various strong acids and bases as a promising electrolyte for high temperature PEM fuel cells but it seems that the doping agent is leaching out with time, something that causes problems in their operation. For these reasons have been developed novel polymeric membranes that can be used as electrolytes at HT-PEMFCs. Two promising membranes are the ADVENT TPS® that contains pyridine units and alternative PBI polymer blends with partially fluorinated polyether ionomer (SFS).
In this work our efforts were primarily concentrated to the examination via FT-IR and FT-Raman of the structural characteristics of the membranes and via the four probe interruption method to the examination of their electrochemical properties. The emphasis was given to the correlation of the spectroscopic evidence of acid interactions with the doping level attained and the ionic conductivity obtained.
Then, we were concentrated to the examination via FT-Raman of the leaching out of the doping agent from the membranes that were protonated /doped by high concentrated phosphoric acid in different doping levels and in different temperatures. The influence of the doping temperature and the effect of the heating, under pressure or without, to the decisive leaching out of an acid-doped PBI membrane were investigated. Both novel membranes seem to bond phosphoric acid better than PBI.