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Anne Peutzfeldt - One of the best experts on this subject based on the ideXlab platform.
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Retention of Propanal and diacetyl in experimental resins.
Acta Odontologica Scandinavica, 1997Co-Authors: Anne PeutzfeldtAbstract:Peutzfeldt A Retention of Propanal and diacetyl in experimental resins.The degree of evaporation from experimental resins containing 0–40 mol% Propanal or diacetyl was determined over a month period at 60°C. From the results the maximum evaporation possible, M∞ was calculated for each resin and was found to vary between 0.28% and 7.51% by weight. At low contents of Propanal or diacetyl, M, remained unchanged as compared with the control resins without additive. At higher contents of additive, M, increased significantly. In resins based on BisGMA and TEGDMA, Propanal was retained to a lesser extent than diacetyl. In resins based on UEDMA and HEMA, Propanal was retained to a greater extent than diacetyl. This study confirms that Propanal and diacetyl become bound in the polymer structure, and theories as to the reaction mechanisms are presented.
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effect of Propanal and diacetyl on quantity of remaining double bonds of chemically cured bisgma tegdma resins
European Journal of Oral Sciences, 1996Co-Authors: Anne Peutzfeldt, Erik AsmussenAbstract:: The aim of the present study was to determine the effect of Propanal and diacetyl addition on the quantity of remaining double bonds of chemically cured dental resins. Propanal (propionaldehyde) or diacetyl (2,3-butanedione) was added to monomer mixtures, which were then made chemically curable. The monomer mixtures were varied with respect to content of Propanal or diacetyl. Addition of Propanal or diacetyl to chemically curable resins resulted in a decrease in the quantity of remaining double bonds from 19.6% to 1.9% and from 19.6% to 11.4%, respectively. A negative correlation of statistical significance was found between content of Propanal and quantity of remaining double bonds, while the relationship between content of diacetyl and quantity of remaining double bonds was found not to be linear. Propanal was equally effective in reducing the quantity of remaining double bonds in chemically cured and in the light cured resins studied previously. As regards diacetyl, a more pronounced effect on quantity of remaining double bonds was noted for light cured resins as compared with chemically cured resins. The most likely common reaction mechanism of Propanal and diacetyl seemed to be that of chain transfer reactions. Furthermore, analysis of the data indicated a possible additional photoinitiating function of diacetyl.
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quantity of remaining double bonds of Propanal containing resins
Journal of Dental Research, 1994Co-Authors: Anne PeutzfeldtAbstract:Improved mechanical properties of resin composites have been reported to be a consequence of the addition of aldehyde to the resins. The objective of the present study was to examine whether this improvement could be attributed to an increased degree of conversion of double bonds. For this purpose, Propanal was added to monomer mixtures, which were then made light-curing. The monomer mixtures were varied with respect to monomer composition and content of Propanal. The quantity of remaining double bonds was determined by means of transmission infrared spectra of the resins recorded before and after wet or dry storage for one week. The addition of Propanal resulted in a decrease in the quantity of remaining double bonds by as much as 89% as compared with the mixtures without Propanal. Negative correlations of statistical significance were found between the content of Propanal and quantity of remaining double bonds in BISGMA:TEGDMA-based as well as in UEDMA:HEMA-based resins for both modes of storage. Signif...
Chenglong Tang - One of the best experts on this subject based on the ideXlab platform.
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shock tube study on Propanal ignition and the comparison to propane n propanol and i propanol
Energy & Fuels, 2016Co-Authors: Ke Yang, Cheng Zhan, Li Guan, Zuohua Huang, Chenglong TangAbstract:High temperature ignition characteristics of Propanal/oxygen mixtures diluted with argon were studied in a shock tube for temperatures ranging from 1050 to 1800 K, pressures ranging from 1.2 to 16.0 atm, fuel concentrations of 0.5, 1.25, 2.0%, and equivalence ratios of 0.5, 1.0, and 2.0. A detailed kinetic model consisting of 250 species and 1479 reactions was developed and validated against experimental results. To clarify the influence of functional groups and their positions on the oxidation, previously measured ignition delay times of propane, n-propanol, and i-propanol were employed for comparison. It was found that ignition delays are in the order of propane > i-propanol > n-propanol > Propanal. Reaction pathway analysis indicated that the intermediate species of propane and i-propanol are rather stable, while the products of n-propanol and Propanal are more reactive, which leads to the decreased ignition delay times. Sensitivity analysis demonstrated that some fuel-specific reactions exhibit relati...
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a comparative study of n propanol Propanal acetone and propane combustion in laminar flames
Proceedings of the Combustion Institute, 2015Co-Authors: Jing Gong, Zuohua Huang, Chenglong Tang, Shuang Zhang, Yu Cheng, Jiaxiang ZhangAbstract:Abstract The laminar flame speeds of C 3 oxygenated fuels ( n -propanol, Propanal and acetone) and hydrocarbon (propane) were measured in a combustion bomb to compare combustion characteristics of C 3 alcohol, aldehyde, ketone, and alkane. Propanal shows the highest flame speeds while acetone gives the lowest one. The experimental observations are further interpreted with chemical kinetic models. The effects of distinctive molecular structures on the fuel consumption pathways are clarified. Propanal generates a large H atom pool that enhances the oxidation, leading to the highest flame speeds. However, acetone forms methyl radical (CH 3 ) and has lower flame speeds as a consequence. The calculated maximum concentrations of H, OH, and CH 3 confirm this analysis. It is found that Propanal yields the highest H and OH concentrations while acetone produces the lowest H and OH concentrations among all tested fuels. Moreover, acetone presents higher CH 3 concentration, especially for fuel rich condition. n -Propanol and propane show comparable flame speeds and similar radical concentrations, especially H and OH. The different kinetics among hydrocarbon species with the same carbon numbers can provide a horizontal view in the hierarchical hydrocarbon chemistry.
Yunming Fang - One of the best experts on this subject based on the ideXlab platform.
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comparative study on the catalytic conversion of methanol and Propanal over ga zsm 5
Fuel, 2016Co-Authors: Mingrui Li, Yuping Zhou, Isaac Nartey Oduro, Yunming FangAbstract:Abstract Comparative study on catalytic conversion of methanol and Propanal over Ga/ZSM-5 is reported in this paper. A series of Ga/ZSM-5 catalysts were obtained by post modification of ZSM-5 in a mixture of Ga(NO 3 ) 3 and NH 4 HF 2 . The obtained zeolite samples were subjected to detailed characterization and catalytic evaluation in methanol and Propanal conversion reactions. It was found that the post-modification step by Ga(NO 3 ) 3 and NH 4 HF 2 had effects both on structure and acidity: (1) decreasing both acid concentration and strength as indicated by NH 3 -TPD, FT-IR analysis and elemental analysis, (2) selective removing the defective zone of ZSM-5 zeolite, and (3) depositing Ga species on zeolite. The catalyst lifetime in methanol conversion reaction was dramatically improved after post-modification; the longest catalyst lifetime of Ga/ZSM-5-1 observed was 14 days. On the contrast, the catalyst lifetime in Propanal conversion was kept constantly at 8 h over all zeolite samples. The different effects of zeolite after post-modification in methanol and Propanal conversion are due to the reactivity difference between methanol and Propanal.
Gerd Maurer - One of the best experts on this subject based on the ideXlab platform.
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reprint of quantitative nmr spectroscopy of binary liquid mixtures aldehyde alcohol part ii Propanal or butanal or heptanal methanol or ethanol or 1 propanol
The Journal of Chemical Thermodynamics, 2013Co-Authors: Silke Jaubert, Gerd MaurerAbstract:Abstract The chemical reactions of aldehydes with alcohols to (hemiacetals and poly(oxymethylene) hemiacetals) have an essential influence on the thermodynamic properties and related phenomena like, for example, the vapor + liquid phase equilibrium of such liquid mixtures. This is well known in the literature for systems such as, for example, formaldehyde and methanol. Experimental information on the chemical reaction equilibria in mixtures with aldehydes other than formaldehyde and alcohols is extremely scarce. Therefore, in the first part of this series, quantitative NMR spectroscopy was used to investigate the chemical reaction equilibrium in binary liquid mixtures of acetaldehyde and an alcohol (methanol or ethanol or 1-propanol) at temperatures between (255 and 295) K. That work is here extended to three other aldehydes, viz. (1-Propanal, 1-butanal and 1-heptanal). The results confirm the expectations from the first part of this series, i.e., that the majority of the constituents of the mixture is present as hemiacetal and the first two poly(oxymethylene) hemiacetals. For example, in an equimolar liquid mixture of {1-heptanal + methanol (or + ethanol or + 1-propanol)} at T = 273 K about 88% (or 81% for both other alcohols) of the aldehyde is bound to hemiacetal and the first two poly(oxymethylene) hemiacetals, i.e., the conversion rates are nearly the same as in the previous investigations with acetaldehyde instead of 1-heptanal. In the series investigated of combinations of aldehydes and alcohols, the particular aldehyde has only a small influence on the conversion rate. In the series of alcohols investigated only methanol has a somewhat larger influence whereas the results (speciation and conversion) for ethanol and 1-propanol are very similar. The NMR-spectroscopic results were also evaluated to determine the mole-fraction based chemical reaction equilibrium constants for the formation of the hemiacetals and the first two poly(oxymethylene) hemiacetals and the chemical reaction enthalpies.
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Reprint of "Quantitative NMR spectroscopy of binary liquid mixtures (aldehyde+alcohol). Part II: (Propanal or butanal or heptanal)+(methanol or ethanol or 1-propanol)"
The Journal of Chemical Thermodynamics, 2013Co-Authors: Silke Jaubert, Gerd MaurerAbstract:Abstract The chemical reactions of aldehydes with alcohols to (hemiacetals and poly(oxymethylene) hemiacetals) have an essential influence on the thermodynamic properties and related phenomena like, for example, the vapor + liquid phase equilibrium of such liquid mixtures. This is well known in the literature for systems such as, for example, formaldehyde and methanol. Experimental information on the chemical reaction equilibria in mixtures with aldehydes other than formaldehyde and alcohols is extremely scarce. Therefore, in the first part of this series, quantitative NMR spectroscopy was used to investigate the chemical reaction equilibrium in binary liquid mixtures of acetaldehyde and an alcohol (methanol or ethanol or 1-propanol) at temperatures between (255 and 295) K. That work is here extended to three other aldehydes, viz. (1-Propanal, 1-butanal and 1-heptanal). The results confirm the expectations from the first part of this series, i.e., that the majority of the constituents of the mixture is present as hemiacetal and the first two poly(oxymethylene) hemiacetals. For example, in an equimolar liquid mixture of {1-heptanal + methanol (or + ethanol or + 1-propanol)} at T = 273 K about 88% (or 81% for both other alcohols) of the aldehyde is bound to hemiacetal and the first two poly(oxymethylene) hemiacetals, i.e., the conversion rates are nearly the same as in the previous investigations with acetaldehyde instead of 1-heptanal. In the series investigated of combinations of aldehydes and alcohols, the particular aldehyde has only a small influence on the conversion rate. In the series of alcohols investigated only methanol has a somewhat larger influence whereas the results (speciation and conversion) for ethanol and 1-propanol are very similar. The NMR-spectroscopic results were also evaluated to determine the mole-fraction based chemical reaction equilibrium constants for the formation of the hemiacetals and the first two poly(oxymethylene) hemiacetals and the chemical reaction enthalpies.
Zuohua Huang - One of the best experts on this subject based on the ideXlab platform.
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shock tube study on Propanal ignition and the comparison to propane n propanol and i propanol
Energy & Fuels, 2016Co-Authors: Ke Yang, Cheng Zhan, Li Guan, Zuohua Huang, Chenglong TangAbstract:High temperature ignition characteristics of Propanal/oxygen mixtures diluted with argon were studied in a shock tube for temperatures ranging from 1050 to 1800 K, pressures ranging from 1.2 to 16.0 atm, fuel concentrations of 0.5, 1.25, 2.0%, and equivalence ratios of 0.5, 1.0, and 2.0. A detailed kinetic model consisting of 250 species and 1479 reactions was developed and validated against experimental results. To clarify the influence of functional groups and their positions on the oxidation, previously measured ignition delay times of propane, n-propanol, and i-propanol were employed for comparison. It was found that ignition delays are in the order of propane > i-propanol > n-propanol > Propanal. Reaction pathway analysis indicated that the intermediate species of propane and i-propanol are rather stable, while the products of n-propanol and Propanal are more reactive, which leads to the decreased ignition delay times. Sensitivity analysis demonstrated that some fuel-specific reactions exhibit relati...
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a comparative study of n propanol Propanal acetone and propane combustion in laminar flames
Proceedings of the Combustion Institute, 2015Co-Authors: Jing Gong, Zuohua Huang, Chenglong Tang, Shuang Zhang, Yu Cheng, Jiaxiang ZhangAbstract:Abstract The laminar flame speeds of C 3 oxygenated fuels ( n -propanol, Propanal and acetone) and hydrocarbon (propane) were measured in a combustion bomb to compare combustion characteristics of C 3 alcohol, aldehyde, ketone, and alkane. Propanal shows the highest flame speeds while acetone gives the lowest one. The experimental observations are further interpreted with chemical kinetic models. The effects of distinctive molecular structures on the fuel consumption pathways are clarified. Propanal generates a large H atom pool that enhances the oxidation, leading to the highest flame speeds. However, acetone forms methyl radical (CH 3 ) and has lower flame speeds as a consequence. The calculated maximum concentrations of H, OH, and CH 3 confirm this analysis. It is found that Propanal yields the highest H and OH concentrations while acetone produces the lowest H and OH concentrations among all tested fuels. Moreover, acetone presents higher CH 3 concentration, especially for fuel rich condition. n -Propanol and propane show comparable flame speeds and similar radical concentrations, especially H and OH. The different kinetics among hydrocarbon species with the same carbon numbers can provide a horizontal view in the hierarchical hydrocarbon chemistry.
