107,345 research outputs found
Spectroscopic investigations of the H3PO4 and H2O uptake of polybenzimidazole membranes for fuel cells
No full textPolybenzimidazole (PBI) doped with H3PO4 is the most commonly used membrane material for high-temperature polymer fuel cells. Proton conductivity is strongly dependent on acid doping and water content (humidity). Despite these facts, only little is known on the chemical equilibria of all species inside the membrane as a function of the composition of the ternary system PBI - H3PO4 - H2O. This includes details on the proton transfer processes, on the dominant conduction mechanisms and on the condensation equilibria, leading to the formation of diphosphoric acid and higher homologues species.
In this study, Raman and NMR spectroscopy is used to investigate the chemical inter¬actions between H3PO4, H2O and PBI vs. the H3PO4 doping level. We obtained information on the H-bond formation between H3PO4 and the polymer chains, on tautomeric processes as well as on the presence of not directly bound H3PO4 at high doping levels. Investigations were performed with uncrosslinked and crosslinked m-PBI and AB-PBI [1-4]. [1] F. Conti, A. Majerus, V. Di Noto, C. Korte, W. Lehnert, D Stolten, Phys. Chem. Chem. Phys. 14, 10022-10026 (2012) [2] F. Conti, S. Willbold, S. Mammi, C. Korte, W. Lehnert, D. Stolten, New J. Chem. 37, 152-156 (2013). [3] A. Majerus, F. Conti, C. Korte, W. Lehnert, D. Stolten, ECS Transaction, in press. [4] G. A. Giffin, F. Conti, S. Lavina, A. Majerus, G. Pace, C. Korte, W. Lehnert, V. Di Noto, Int. J. Hydrogen Energy, submitted
Spectroscopic Investigation of the Acid and Water Uptake of Polybenzimidazole Membranes for Fuel Cells
No full textPolybenzimidazole (PBI) doped with H3PO4 is the most commonly used membrane material for high-temperature polymer fuel cells. Proton conductivity is strongly dependent on acid doping and water content. Despite these facts, only little is known on the chemical equilibria of all species inside the membrane as a function of the composition of the ternary system PBI - H3PO4 - H2O. This includes details on the proton transfer processes, on the dominant conduction mechanisms and on the condensation equilibria, leading to the formation of diphosphoric acid and higher homologues species.
In this study, Raman and NMR spectroscopy is used to investigate the chemical interactions between H3PO4, H2O and PBI vs. the H3PO4 doping level. We have obtained information on the H-bond formation between H3PO4 and the polymer chains, on tautomeric processes as well as on the presence of not directly bound H3PO4 at high doping levels. Investigations were performed with uncrosslinked and crosslinked m-PBI and AB-PBI [1-4]. [1] F. Conti, A. Majerus, V. Di Noto, C. Korte, W. Lehnert, D Stolten, Raman study of the polybenzimidazole–phosphoric acid interactions in membranes for fuel cells, Phys. Chem. Chem. Phys. 14 (2012) 10022. [2] F. Conti, S. Willbold, S. Mammi, C. Korte, W. Lehnert, D. Stolten, Carbon NMR investigation of the polybenzimidazole–dimethylacetamide interactions in membranes for fuel cells, New J. Chem. 37 (2013) 152. [3] A. Majerus, F. Conti, C. Korte, W. Lehnert, D. Stolten, Thermogravimetric and Spectroscopic Investigation of the Interaction between Polybenzimidazole and Phosphoric Acid, ECS Transaction (2013) accepted. [4] G. A. Giffin, F. Conti, S. Lavina, A. Majerus, G. Pace, C. Korte, W. Lehnert, V. Di Noto, A vibrational spectroscopic and modeling study of poly(2,5-benzimidazole) - phosphoric acid interactions, Int. J. Hydrogen Energy (2013) accepted
Ex-situ NMR and Raman studies of H3PO4 and H2O uptake of polybenzimidazole membrane for PEMFC
No full text: Polybenzimidazole (PBI) doped with H3PO4 is the most commonly used membrane mate-rial for high-temperature polymer fuel cells. Despite this fact, only less is known on the chemical equilibria of all species inside the membrane as a function of the com¬position of the ternary system PBI - H3PO4 - H2O. This in¬clu¬des details on the proton transfer pro¬ces-ses, on the dominant conduc¬tion me¬cha¬nisms and on the con¬densation equilibria, lea-ding to the formation of di¬phos¬pho¬ric acid and higher homo¬logues species.
In this study Raman and NMR spectroscopy is used to in¬vestigate the chemical inter¬ac-tions between H3PO4, H2O and PBI vs. the H3PO4 doping level. We could ob¬tain in¬forma-tion on the H-bond formation between H3PO4 and the polymer chains, on tauto¬me¬ric pro-ces¬ses as well as on the presence of not directly bounded H3PO4 at high do¬ping levels [1,2]. Investigations were performed with uncrosslinked and cross¬linked m-PBI and AB-PBI. [1] F. Conti, A. Majerus, V. Di Noto, C. Korte, W. Lehnert, and D. Stolten, Phys. Chem. Chem. Phys. 14, 10022-10026 (2012) [2] F. Conti, S. Willbold, S. Mammi, C. Korte, W. Lehnert, and D. Stolten, New J. Chem. 37, 152-156 (2013)
JAMES RODGERS, Bassoon MASTER'S RECITAL Thursday, January 16, 1992 8:00 p.m. Lillian H. Duncan Recital Hall
No full textProgram: Sonata for bassoon and piano, op. 168 / Camille Saint-Saëns (1835-1921) -- Sonatine for bassoon and piano / Alexandre Tansman (1897-1986) -- Demiola for solo bassoon and tape / Karl Korte -- Rondeaux e virelais for solo bassoon / Jeffrey Nytch.This recital is given in partial fulfillment of the requirements for the Master of Music degree
CHAMBER MUSIC RECITAL Thursday, March 11, 2004 8:00 p.m. Lillian H. Duncan Recital Hall
No full textProgram: Quintet for Wind Instruments / Walter Piston (1894-1976) -- Trio for Flute, Bassoon, and Piano / Gaetano Donizetti (1797-1848) -- Demiola / Karl Korte (b. 1928) -- Mladi (Youth) / Leos Janacek (1854-1928)
H. Riffelmacher et Walther V. Lœwenich, Synchronistische Rissgeschichts-Korte : Reformation und Gegenreformation, 1517-1648
No full textFebvre Lucien. H. Riffelmacher et Walther V. Lœwenich, Synchronistische Rissgeschichts-Korte : Reformation und Gegenreformation, 1517-1648. In: Annales. Economies, sociétés, civilisations. 11ᵉ année, N. 3, 1956. pp. 411-412
TEXAS Duos Tuesday, March 3, 1992 8:00 p.m. Lillian H. Duncan Recital Hall
No full textPresented by Texas Composers ForumProgram: Five dialogues / Richard Willis -- Song of a caged bird / Scott McAllister -- Colloquy / Fisher Tull -- Demiola / Karl Korte -- Elegies / Paul Cooper
Diagnostic Raman signals of the interaction polybenzimidazole – phosphoric acid in membrane for Fuel Cells
No full textOne fundamental component of a fuel cell is the electrolyte, which separates the electrocatalytic active sites of the two electrode configurations. Phosphoric acid-doped poly(2,2’-(m-phenylene)-5,5’-bibenzimidazole) (PBI) polymers have been studied as membrane materials for the use in High Temperature Polymer Electrolyte Fuel Cells (HT-PEFC), since they can be used at temperatures as high as 200 °C without humidification. Among the many possible PBI derivatives, a very promising material is poly(2,5-benzimidazole) (AB-PBI). [1-4]
In the present study, we report on a FT-Raman investigation of AB-PBI polymer membranes doped with various concentrations of ortho-phosphoric acid. Characteristic Raman spectra with three diagnostic regions and specific peaks have been studied. The information is of fundamental importance in order to elucidate the role of phosphoric acid in the conductivity mechanism of AB-PBI. [5]
Reference:
[1] J. N. Asensio, E. M. Sánchez and P. Gómez- Romero, Chem. Soc. Rev., 2010, 39, 3210-3239.
[2] C. Wannek, B. Kohnen, H.-F. Oetjen, H. Lippert and Mergel J., Fuel Cell, 2008, 8, 87-95.
[3] C. Wannek, W. Lehnert and J. Mergel, J. Power Sources, 2009, 192, 258-266.
[4] K. Wippermann, C. Wannek, H.-F. Oetjen, J. Mergel and W. Lehnert, J. Power Sources, 2010, 195, 2806-2809.
[5] F. Conti, A. Majerus, V. Di Noto, C. Korte, W. Lehnert, D. Stolten, Phys. Chem. Chem. Phys., 2012, 14, 10022-10026
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
ELLEN CONNORS Bassoon SENIOR RECITAL Sunday, January 22, 2006 1:00 p.m. Lillian H. Duncan Recital Hall
No full textProgram: Sonata No.5 in C Minor, Op. 50 / Joseph Bodin de Boismortier (1689-1755) -- Demiola (for bassoon and tape) / Karl Korte (b.1928) -- My Grandfather's Clock / William Foote (1862-1940) -- Inverted Music / Nico Muhly (b.1982) -- Concertpiece No.1 / Felix Mendelssohn (1809-1847).This recital is given in partial fulfillment of the requirements for the degree Bachelor of Music
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