Differential scanning calorimetry measurement

Differential scanning calorimetry measurements have shown a marked cooling/heat-ing cycle hysteresis and that water entrapped in AOT-reversed micelles is only partially freezable. Moreover, the freezable fraction displays strong supercooling behavior as an effect of the very small size of the aqueous micellar core. The nonfreezable water fraction has been recognized as the water located at the water/surfactant interface engaged in solvation of the surfactant head groups [97,98]. 

TGA analysis shows that polymer degradation starts at about 235°C which corresponds to the temperature of decomposition of the cellobiose monomer (m.p. 239°C with decom.). Torsion Braid analysis and differential scanning calorimetry measurements show that this polymer is very rigid and does not exhibit any transition in the range of -100 to +250 C, e.g. the polymer decomposition occurs below any transition temperature. This result is expected since both of the monomers, cellobiose and MDI, have rigid molecules and because cellobiose units of the polymer form intermolecular hydrogen bondings. Cellobiose polyurethanes based on aliphatic diisocyanates, e.g. HMDI, are expected to be more flexible. 

Peak temperatures (°C) determined by differential scanning calorimetry measurements on heating... 

Kowalski, B., Gruczynska, E., and Maciaszek, K. 2000. Kinetics of Rapeseed Oil Oxidation by Pressure Differential Scanning Calorimetry Measurements. Ear. I Lipid Sci. Technol., 102, 337-341. 

Differential scanning calorimetry measures heat flow as a function of temperature. When starch is heated in the presence of excess water, a sharp peak (an endotherm) is obtained, which is caused by the disordering of... 

Fig. 6.24. Differential scanning calorimetry measurements of the heat released during equilibration of n-type a-Si H after (a) fast and b) slow cooling (Matsuo et al. 1988).

Differential scanning calorimetry measures the thermodynamic parameters associated with thermally induced phase transitions. Here, the sample of interest and an inert reference are heated or cooled independently at a programmed rate, and in tandem, such that their temperatures change in unison and the differential temperature is maintained at zero. If the sample undergoes a thermally induced transition, heat must be applied to or withdrawn from the sample in order to maintain the same temperature in both sample and reference compartments. The instrument measures the heat flow into the sample relative to the reference and this dijferential heat flow (or excess specific heat) is recorded as a function of temperature, resulting in a trace, as shown in Fig. 1... 

Figure 6 Chemical structure of poly(9,9-dioctylfluorene) and Differential Scanning Calorimetry measurements of its thermal propertiesf Trace (i) shows the heat flow on slow cooling from the melt, trace (ii) on subsequent heating and trace (Hi) on heating a film quenched rapidly from the melt.

Synchrotron-x>ray powder-diffraction and differential-scanning-calorimetry measurements on solid Cso reveal a first-order phase transition from a low-temperature simple-cubic structure with a four-molecule basis to a face-centered-cubic structure at 249 K. The free-energy change at the transition is approximately 6.7 J/g. Model fits to the diffraction intensities are consistent with complete orientational disorder at room temperature, and with the development of orientational order rather than molecular displacements or distortions at low temperature. 

Differential scanning calorimetry measurements of poly(OVE-co-AN)/SAN blends shown in Figure 2 reveal the shift of glass transition temperature from the lowest Tg, which corresponds to the poly(OVE-co-AN) to the highest Tg of SAN. One Tg value of the blend confirmed the miscibility of the poly(OVE-co-AN)/SAN blends. 

Palchik [182] obtained nanosized amorphous iron oxide (Fe203) by the pyrolysis of iron pentacarbonyl, Fe(GO)5, in a modified domestic microwave oven in refluxing chlorobenzene as solvent under air. The reaction time was 20 min. Separate particles of iron oxide, 2-3 nm in diameter, were obtained together with aggregated spheres with a diameter of 25-40 nm. Differential scanning calorimetry measurements showed an amorphous/crystalline phase transition at about 250 °C. 

In terms of structure of the membranes the first point to be discussed concerns the possibility of having crystalline domains and the role of these domains. X ray and differential scanning calorimetry measurements are the best ways to probe the existence and the structure of crystalline domains. Figure 1 represents different X ray scattering curves obtained for ... 

Differential scanning calorimetry measurements were done in a Perkin-Elmer DSC-2 calorimeter at a scanning rate of 20 C per minute. 

Antonsen, K. P., Hoffman, A. S., Water structure of PEG solutions by differential scanning calorimetry measurements, in Poly(ethylene glycol) Chemistry Biotechnical and Biomedical applications (J.M. Harris, Ed.), Plenum Press, New York, 1992, pp. 15-28. 

The alteration of heats of adsorption by SMSI is still a controversial matter. From differential scanning calorimetry measurements Vannice et al. (72) originally reported an increase in the heat of adsorption of H2 with Pt particle size, but not much effect of the support or reduction temperature. More recently (73) they have corrected the earlier work to conclude... 

Differential scanning calorimetry measurements are also consistent with the loss of ethylene glycol In the early stages of the conversion of this precursor to the 1-2-3 superconductor. As Is shown In Figure 2, a small endotherm Is observed at around 200 °C which Is attributed to the evaporation of ethylene glycol. This Is followed In the DSC by a broad exotherm from 220 to 400 °C, which associated with the thermal decomposition reaction. 

Differential scanning calorimetry measures the specific heat, Cp, which is related to the enthalpy //by Cp = (BH/dT)p, as a function of temperature on heating at a constant rate. Therefore, enthalpy changes occurring on aging below the glass transition... 

Figm 13 (a) Sequence and schematic representation of the self-assembly of an amphiphilic diblock elastin polypeptide into core-shell nanoparticles. Elastin-mimetic protein polymers that comprise fusions of elastin sequences with different 7, values can be induced to undergo self-assembly at a temperature between the two transition temperatures, (b) Differential scanning calorimetry measurements indicate an endothermic transition for the more hydrophobic (lower 7 block with a value that corresponds to those observed for the burial of hydro-phobic residues within a folded protein, (c) This transition coincides with the formation of spherical assemblies in which the more hydrophobic block is confined within the micellar core. Transmission electron microscopy measurements are consistent with spherical micelles and more complex assemblies. Reprinted from Lee, T. A. T. Cooper, A. Apkarian, R. P. Conticello, V. P. Adv. Mater. 2000, f2(15), Copyright 2000, with... 

DSC (Differential Scanning Calorimetry) measurements showed that the Tg increased when the size of the side groups increased. 

Differential scanning calorimetry measurements suggest that the surface treatment of affects the crystallization properties of the PLA matrix. 

In the differential scanning calorimetry, measurements are made for the specific heat, heats of melting, vaporization, decomposition, etc., in a differential scanning calorimeter and the data are used in the following equation to calculate the heat of gasification, such as for a melting polymer [2] ... 

DSC Differential scanning calorimetry, measurement melting temperatures, glass transition temperature and heat of melting lower temperature range than DTA. 

Differential scanning calorimetry measurements exist on solvent molecules constrained in the pores of a variety of PDMS elastomers. Some results on trimodal networks have been reported. The several... 

The authors prepared other oligomers with 3,3 -methylenebisbenzeneamine and 3,3 -carbonylbisbenzeneamine as diamine components. The results of differential scanning calorimetry measurements listed in Table 8 indicate the thermal range of polymer flow for polyimide 51 as a function of its molecular weight. is the temperature where the polyimide starts to flow, represents the temperature corresponding to the minimum of the endothermic peak and is the maximum of the exothennic polymerisation peak. Note that endothermic and exothermic... 

The freezing points of solvents absorbed into bimodal networks are also of interest since solvent molecules constrained to small volumes form only relatively small crystallites upon crystallization, and therefore exhibit lower crystallization temperatures. " Differential scanning calorimetry measurements on solvent molecules constrained in the pores of PDMS elastomers gave evidence for several crystallization temperatures, which could be indicative of an unusual distribution of pore sizes. Calorimetric measmements on bimodal poly(ethylene oxide) networks indicated that the short chains seemed to decrease the amount of crystallinity in the unstretched state. This is an intriguing result since they inaease the extent of crystallization in the stretched state. A similar study on poly (tetrahydrofuran) did not show any decrease, however. ... 

Differential scanning calorimetry measures heat capacity directly, rapidly, and accurately, so it is an ideal technique for the determination of the glass transition temperature, 7. ... 

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