Calorimetric Investigations

In copolymers of group B the Curie transition appears in the differential scanning calorimetric curve as a broad peak, extending over a temperature interval which narrows down with increasing VF2 content. The transition 

A schematic phase diagram summarizing the three temperature regions (Ff, Fnf and melt) is shown in Fig. 9. For VF2 compositions below 82%, at room temperature, one observes the predominant ferroelectric phase. With increasing temperature, the paraelectric phase appears and at higher temperatures one obtains the molten state of the paraelectric crystallites. The Tm values of the copolymers are considerable lower than those of both homopolymers and show 

The melting temperature and melting enthalpy are, however, unchanged under poling and are only slightly affected by crystallization conditions since the influence of the preparation conditions is lost during the Curie transition. It is noteworthy that the enthalpy at the Curie transition Ah (up) increases with the 

As already discussed in Sect. 5.3.2, the lamellar L to lyo-SmC phase transition seems to shift from 1st to 2nd order with increasing formamide concentration. To further confirm this crossover, the thermodynamic nature of the phase transition was investigated by differential scanning calorimetry (DSC). For this, samples with different concentrations of formamide were measured on heating and cooling cf. Sect. 4.2). The detected heat flow of the individual samples is plotted in Fig. 5.30. 

530 DSC thermograms measured on heating (fop) and cooling (bottom) for different compositions of C50 and formamide. Peaks corresponding to a phase transition between the lyotropic SmC analog and a further liquid crystalline phase are highlighted in yellow 

In the mixture with 7 wt% of formamide three liquid crystalline phases can be found, namely the lyotropic SmC analog phase, the Coli phase and the lamellar L phase. The mixtures between 12 and 22 wt% of formamide only exhibit the lyotropic SmC analog phase and the lamellar L phase. While the DSC curves of the sample with 12 wt% of formamide still show a very pronounced peak at the lyotropic SmC analog to lamellar L phase transition, the peak becomes smaller and 

Furthermore, the phase transition temperatures detected by means of differential scanning calorimetry match those determined by polarized optical microscopy. The DSC measurements thus also confirm the phase diagrams shown in Fig. 5.15. 

31 Enlargement of the DSC thermograms of the C50 samples with a 18 wt% of formamide and b 22 wt% of formamide. Peaks corresponding to the lamellar L to lyo-SmC phase transition and vice versa are highlighted in yellow 

The experimental protocol for measuring heat of mixing of gas in liquid absorbent will depend on the chosen technique. 

Using flow techniques (or dynamic technique), the gas and the absorbent solution flow separately in narrow tubes to a mixing point. Then the mixture flows in a common mixing tube located in the sensible part of the calorimeter. The heat power due to gas dissolution is then detected along the mixing tube, by a thermopile in Calvet 

MDEA solution, the enthalpy decrease starts at loading charge about 0.9. The MDEA is a tertiary amine and then does not form carbonate. The chemical mechanism of CO2 absorption corresponds only to formation of carbonate. However the enthalpy of solution decreases at loading charge about 0.9. This phenomena is observed because of one part of CO2 is physically dissolved. 

The environmental impact of CO2 must be considered and it is urgent to reduce its anthropogenic emission. Solutions have to be proposed for near future. One option is a decarbonation of post combustion effluents. Design and development of future industrial process for CO2 separation from fumes will require smdies of gas dissolution in various selective absorbent solutions. 

Aqueous solutions of amine are considered as promising solvent but the selection of the best adapted molecule is still open. Then important experimental work will be necessary to characterize and test the dissolution of carbon dioxide. In this domain, determination of calorimetric properties such as enthalpy of solution of carbon dioxide in absorbent solutions will be essential. The enthalpies of solution are particularly important for the estimation of the energy required for the solvent regeneration step of an industrial process. For theoretical point of view, this thermodynamic property participates to the development of thermodynamic models representative of gas-absorbent systems. This chapter has focused on mixing calorimetric techniques used to investigate gas dissolution in liquid absorbents. The presented techniques can be adapted, in studies of CO2 dissolution in aqueous solution of amines, to investigate for example each chemical reaction involved such as amine protonation or carbamate formation. 

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The reactions depicted in Eq. (1) are suitable for calorimetric investigations since they proceed rapidly and quantitatively as monitored by NMR. spectroscopy. The. solution calorimetric protocol has been described elsewhere." The enthalpy values were determined by anaerobic solution calorimetry in THF at 30 C by reacting 4 equivalents of each carbene with one equivalent of tetramer. The results of this study are presented in Table I. 

Calorimetric investigation of a Diels Alder reaction between propenal and a triene, which had caused problems on scale-up, showed, after the exotherm due to the Diels Alder reaction, and from a temperature a litle above 200°C, a second, more exothermic, reaction with a very fast pressure rise which burst the ARC can employed. This is presumably aromatisation of the alkenylcyclohexenealdehyde first formed, with probable liberation of hydrogen and carbon monoxide. 

Sorai (2001) Calorimetric investigations of phase transitions occurring in molecule-based materials in which electrons are directly involved [250]. 

In consideration of thermal stability, a calorimetric investigation of Ure2p prion domain-containing filaments detected no evidence of these domains denaturing up to 105°C (Baxa et al., 2004). In comparison, most proteins denature at temperatures of 50—70°C and rarely exceed 80—90°C, except for proteins of extreme thermophiles. 

Calorimetric investigations of hydrous metal oxide suspensions are more scarce. A study of starch adsorption on hematite revealed that the adsorption process became less exothermic as surface coverage increased (25). This was attributed to a rearrangement of starch molecules to less favorable configurations. 

M. Reading, D. Elliot, V L. Hill. /I New Approach to the Calorimetric Investigation of Physical and Chemical Transitions. J. Thermal Anal. 1993, 40, 949-955. 

Further evidence of the peculiar behaviour of the liquid at this composition may be obtained by measuring several other properties. Enthalpies of mixing of liquid Li-Pb alloys were determined by Predel and Oehme (1979) over the entire concentration range through calorimetric investigations (see Fig. 3.2). 

Taquet A, Labarbe R, Houssier C (1998) Calorimetric investigation of ethidium and netropsin binding to chicken erythrocyte chromatin. Biochemistry 37(25) 9119—9126 Temple MD, McEadyen WD, Holmes RJ, Denny WA, Murray V (2000) Interaction of cisplatin and DNA-targeted 9-aminoacridine platinum complexes with DNA. Biochemistry 39(18) 5593-5599 Terasaki T, Iga T, Sugiyama Y, Hanano M (1984) Interaction of doxorubicin with nuclei isolated from rat liver and kidney. J Pharm Sci 73(4) 524—528... 

Thermodynamic data on amphibole end-members are mostly derived from phase equilibria, because of the difficulty of synthesizing pure components for direct calorimetric investigation. Table 5.49 lists existing values for some pure components. Most data come from the internally consistent set of Holland and Powell... 

Haselton H. T, Hovis G. L., Hemingway B. S., and Robie R. A. (1983). Calorimetric investigation of the excess entropy of mixing in analbite-sanidine solid solutions Lack of evidence for Na, K short range order and implications for two feldspar thermometry. Amer. Mineral, 68 398-413. 

Hovis G. L. and Waldbaum D. R. (1977). A solution calorimetric investigation of K-Na mixing in a sanidine-analbite join-exchange series. Amer. Mineral, 53 1965-1979. 

While numerous nitrones react with olefins to form isoxazolidines (l-oxa-2-azacyclo-pentanes) by a formally simple [3 + 2] cycloaddition reaction, there have been few calorimetric investigations of this process. Among these is the reaction of some -substituted... 

Apin et al (Ref 4), in a calorimetric investigation of mixtures of Hydrazine Azide with several metallic elements found that an explosion resulted with the formation of NH3. The amount of NH3 depended on the explosion conditions. The limiting conditions were either N21VHN3 >2 AHj +2 AN2 or 1 2/3NH3 + 1 2/3N2... 

One of the principal objectives of any immersional calorimetric investigation of organic fibrous materials is to assess the thermodynamic functions... 

Anokhina, M.S., Il in, M.M., Semenova, M.G., Belyakova, L.E., Polikarpov, Yu.N. (2005). Calorimetric investigation of the thermodynamic basics of the effect of malto-dextrins on the surface activity of legumin in the presence of small-molecule surfactants. Food Hydrocolloids, 19, 455 166. 

Because of the question raised by the recent calorimetric investigations (40, 41) as to whether the hydrogen-hydrogen interaction contains a significant entropic contribution, it was decided to determine P-C-T over a temperature range similar to that used when the calorimetric data were determined. 

Muller, F. H. Thermodynamics of deformation. Calorimetric investigation of deformation processes, in Rheology, New York Academic Press, Vol. 5, 417 (1969)... 

This conclusion was derived by Pimenova and her coworkers47 and by A. E. Deezer, W. Liittke, A. deMeijere and C. T. Mortimer, J. Chem. Soc. (B), 648 (1966) as part of their calorimetric investigations of the methyltercyclopropyls and bicyclopropyl, respectively. 

In the case of copolymers a calorimetric investigation by Dole and Wunderlich (1959) of the copolyester, polyethylene terephthalate and sebacate) at the 80/20. (80 moles of terephthalate units to 20 of sebacate)... 

L.A. Marky, D. Patel, and K. J. Breslauer, Effect of Tetramethylammonium Ion on the Helix-to-Coil Transition of Poly(deoxyadenylylthymidine) A Nuclear Magnetic Resonance and Calorimetric Investigation , Biochemistry, 20, 1427-1431 (1981). 

For the separate calorimetric investigation, the quality of the fit to the model was similar to that for the combined investigation discussed above (A q = 173 W2, A A = 2.685). In this determination, the error for the infrared measurements, A A, was obtained by using the kinetic parameters obtained from fitting the calorimetric data to calculate concentration-time... 

Heintz, A. and Ch. Illenberger. 1998. Thermodynamics of vanadium redox flow batteries Electrochemical and calorimetric investigations. Ber. Bunsenges. Phys. Chem. 102 1401-1409. 

Many calorimetric investigations have been reported on microbial systems in fundamental metabolic studies and in work directed towards applications in biotechnology, ecology, pharmacology, and the clinical areas. Two examples are given here. 

The model described in Figure 13.5 takes into account both the physical and chemical effects of the interlayers but the chemical ones, which are reflected, for example, in the ignition time, have not yet been discussed. A number of cone calorimetric investigations reported a decrease of the time to ignition (TTI) in presence of clay nanofillers. Such results can be seen in Table 13.2 for MMT and sepiolite (SEP) clay types. 

Eliasson, A.-C. (1992). A calorimetric investigation of the influence of sucrose on the gelatiniza-tion of starch. Carbohydr. Polym. 18 131-138. 

CALORIMETRIC INVESTIGATION OF HYDROGEN INTERACTION WITH ZrMn2... 

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