Authors:L. Núńez-Regueira, S. Gómez-Barreiro, and C. A. Gracia-Fernández
Modulated differential scanning calorimetry (MDSC) and dielectric analysis (DEA) have been used to characterize the cure process
of the system diglycidyl ether of bisphenol A (DGEBA(n=0)/1,2 diaminocyclohexane (1,2 DCH). The trans isomer and a mixture cis/trans(30-70% respectively) of 1,2 DCH were used to find their different behaviour. The study allowed to check the influence of
the cisisomer on the thermoset curing process. Gelation times were obtained through the equation proposed by Johari and vitrification
times from the point of inflection of the complex calorific capacity modulus.
Authors:GheorghiŢa Dincă, Marius Sorin Dincă, and Maria LetiŢia Andronic
implications on public sector's efficiency. In order to establish the degrees of efficiency and inefficiency of the national health systems we used the Data Envelopment Analysis (DEA). 1 DEA is also used to identify the countries that have the highest
Authors:Shravan Singh Thakur, Manik Pavan Kumar Maheswaram, Dhruthiman Reddy Mantheni, Lakshmi Kaza, Indika Perara, David W. Ball, John Moran, and Alan T. Riga
data on the three USP ingredients based on the endothermic (heat-absorbing) and exothermic (heat-evolving) processes.
Finally, dielectric analysis (DEA) is used for measuring the dielectric properties of the three USP ingredients [ 16 ]. DEA has
Authors:Libby Yoerg, M. Ellen Matthews, Lakshmi Kaza, Naullage Indika Perera, David W. Ball, John Moran, and Alan T. Riga
, including melting point (for crystalline materials) and glass transition (for amorphous materials). Dielectric analysis (DEA) reveals increasing amorphicity and molecular rearrangement depicted by the increased organization of the dielectric relaxation
framework, while Section 4 presents the results of the Data Envelopment Analysis (DEA) efficiency computations. Section 5 examines the correlation between the DEA efficiency scores and the country's GDP per capita. The article ends with a theoretical
Authors:C. Kinart, W. Kinart, D. Checinska-Majak, and A. Bald
Densities () and relative permittivities () of numerous binary mixtures of 2-methoxyethanol (ME) (1)+diethylamine (DEA) (2) at four temperatures and 2-methoxyethanol (1)+triethylamine (TEA) (2) at five temperatures, between (291.15 and 313.15) K, are reported. These results are used to calculate excess molar volumes, and deviations in the relative permittivities. The results are fitted to the Redlich-Kister polynomial equation to estimate the binary coefficients and standard errors. Furthermore, the experimental results are used to disclose the nature of binary interactions in the bulk of studied the binary mixtures.
Authors:A. S. Tompa, R. F. Boswell, P. Skahan, and C. Gotzmer
The dinitramide salts of ammonia (ADN), hexamethylenetetramine (HDN), potassium (KDN), and sodium (NaDN) showed a linear relationship between the DSC rate of decomposition at the peak maximum and the DEA tanδ value at the low temperature transition peak. As the cation basicity increased in the series ADN<HDN<KDN<NaDN, there was an increase in the low temperature transition peak, the energy barrier for relaxation, and the decomposition peak temperature, and a decrease in the tanδ value at the low temperature transition peak, specific heat capacity, and the rate and enthalpy of decomposition. The more basic salts were more thermally stable (i.e., higher decomposition temperature) and less energetic (i.e., lower enthalpy of decomposition). The more internal free volume (disorder) present in these salts, the higher the rates of relaxation and decomposition. Five aluminum powders of different surface areas were analyzed by DSC in platinum sample pans, and it was found that the enthalpy and rate of oxidation increased as the particle size of Al decreased while the enthalpy of the Al melt decreased. TG showed a two-step weight gain in the oxidation of Al with plateaus in the 650 and 1130°C regions and the percent weight gain increased as the particle size of Al decreased. Variable DSC and TG heating rate studies showed that the activation energies for the first step in the oxidation process increased as the particle size of Al increased.
Authors:Lisardo Núñez-Regueira, M. Villanueva, I. Fraga, C. A. Gracia-Fernández, and S. Gómez-Barreiro
The thermal degradation
of an epoxy system consisting of a diglycidyl ether of bisphenol A (DGEBA, n=0) and m-xylylenediamine (m-XDA)
was studied by both thermogravimetric analysis (TG) and dielectric analysis
(DEA). It has been checked a deviation of the typical behaviour in the Arrhenius
plot expected for this kind of systems, owing to the thermal degradation.
Both, structural relaxation time and conductivity values, were represented
as a function of the mass loss, that allow a relationship to be obtained between
characteristic relaxation time and the degree of degradation at the beginning
of the degradation process.
Authors:Ladislava Issever Grochová and Kateřina Myšková
Allen , K.
( 1999 ): DEA in the Ecological Context - An overview . In: Westermann , G. (ed.): Data Envelopment Analysis in the Service Sector . Harzer Wirtschaftswissenschaftliche Schriften, 203 – 235
Many of the isomers of polybutadiene and polyisoprene elastomers can be characterized by thermal analysis.Tg is sensitive to side chain units (1,2 or 3,4 structure) for both polymers. Crystallinity measurements can characterizecis andtrans isomers. DMA and DEA master curves provide an idea of the heterogeneity of the chain units from the width of the loss factor
curves in theTg region. Thermal and thermooxidative degradation, as followed by DSC and DTG, can differentiate specific natural and synthetic
isomers of polyisoprenes in raw and vulcanized states.