Comparison with differential scanning

Semerak SN, Frank CW (1983) Excimer fluorescence as a molecular probe of blend miscibility—comparison with differential scanning calorimetry. Adv Chem Ser 203 757-771... 

Figure 3. Comparison of differential scanning calorimetric data (parts A and B) with thermomechanical analysis data (part C) for a cobalt chloride modified BTDA-ODA polyimide film.

R. H. Wrlson, B. J. Goodfellow, P. S. Belton, B. G. Osborne, G. Oliver, P. L. Russell. Comparison of Fourier Transform mid infrared reflectance spectroscopy with differential scanning calorimetry for the study of the staling of bread. J Sci FoodAgric 54 471-483, 1991. 

Probably the main weakness of DTA as a method of analysis remains the difficulty of linking the thermal changes shown on the thermogram, with the actual thermal processes taking place. It should be noted that data obtained by DTA are often similar to those available for differential scanning calorimetry. Indeed the two techniques overlap extensively and may be seen as complementary. A comparison of the two techniques is made at the end of the next section. 

The preparation of immiscible polymer blends is another way to disperse a bulk polymer into fine droplets. It has been reported for several polymers that when they are dispersed in immiscible matrices into droplets with average sizes of around 1 pm, they usually exhibit multiple crystallization exotherms in a differential scanning calorimetry (DSC) cooling scan from the melt (at a specific rate, e.g., 10 Cmin ). Frensch et al. [67] coined the term fractionated crystallization to indicate the difference exhibited by the bulk polymer, which crystallizes into a single exotherm, in comparison with one dispersed in a large number of droplets, whose crystallization is fractionated temperature-wise during cooling from the melt. 

Abstract. Gas interstitial fullerenes was produced by precipitation of C6o from the solution in 1,2 dichlorobenzene saturated by O2, N2, or Ar. The structure and chemical composition of the fullerenes was characterized by X-ray powder diffraction analysis, FTIR spectroscopy, thermal desorption mass spectrometry, differential scanning calorimetric and chemical analysis. The images of fullerene microcrystals were analyzed by SEM equipped with energy dispersive X-ray spectroscopy (EDS) attachment. Thermal desorption mass spectroscopy and EDS analysis confirmed the presence of Ar, N and O in C60 specimens. From the diffraction data it has been shown that fullerite with face centered cubic lattice was formed as a result of precipitation. The lattice parameter a was found to enhance for precipitated fullerene microcrystals (a = 14.19 -14.25 A) in comparison with that for pure C60 (a = 14.15 A) due to the occupation of octahedral interstices by nitrogen, oxygen or argon molecules. The phase transition temperature and enthalpy of transition for the precipitated fullerene microcrystals decreased in comparison with pure Cgo- Low temperature wet procedure described in the paper opens a new possibility to incorporate chemically active molecules like oxygen to the fullerene microcrystals. 

Figure 7.53. Differential scanning calorimetry (DSC). Shown are (a) schematic of the heat-flux sample chamber (b) an example of a DSC thermogram, showing endothermic eventsbDf (c) DSC thermogram of a poly(vinyUdene fluoride)-ethyl acetoacetate polymer-solvent system, showing two melting events for the polymer due to its intermolecular interactions with solvent molecules. The inset shows a comparison between the pure polymer (b) and the polymer-solvent (a). Reproduced with permission from Dasgupta, D. Mahk, S. Thierry, A. Guenet, J. M. Nandi, A. K. Macromolecules 2006, 39,6110.

Comparison of several techniques (namely Fourier transform infrared spectroscopy (FTIR), simultaneous thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) and ultrasonic spectroscopy) for assessing the residual physical and mechanical characteristics of polymer matrix composites (PMCs) exposed to excessive thermal loads showed the measured power spectra of ultrasonic energy to correlate with performance of graphite fibre epoxy matrix composites exposed to thermal degradation, and also that analyses with the three techniques all pointed to the same critical temperature at which thermally induced damage increased sharply [58],... 

Differential Scanning Calorimetiv has been used for studying the interaction of labdanes 1 (labd-13(E)-ene-8a,15-diol), 2 (labd-13(E)-cne-8a-oI-15-yl-acetate) and 3 (Iabd-14-ene-8,13-diol (Sclareol)) Fig. (12) [76-77] with DPPC model lipid bilayers. The thermotropic changes caused by the labdanes in DPPC bilayers could be used for evaluating the incoiporation efficiency of labdanes in DPPC liposomes. Furthermore in these studies [29, 76], a comparison with the structurally similar molecule to cholesterol was carried out based on their thermotropic behavior. The development of liposomal formulations incorporating 1 and 2 has been achieved, wliile the stability studies of the liposomal formulations based on ,-potential and on liposomal size have been evaluated. 

In most cases, the purity of a pharmaceutical substance is determined by comparison of the reference standard with the known purity assigned. On the other hand, when no reference standard sample is available, the purity is determined by an absolute method in which the calculated result is based on theory and not by a comparative method. Purity established by analytical methods such as phase-solubility analysis or differential scanning calorimetry (DSC) is known as absolute purity (Figs. 3 and 4). 

The crystallization kinetics of native P(3-hydroxyalkanoic acid) (PHA) granules isolated from the strains of A. eutrophus and P. oleovorans have been studied by measurements of the glass-transition temperature with a differential scanning calorimeter [36]. The comparison is made between PHA in vivo and the isolated polymer. It is demonstrated that the native granules do not contain a plasticizer and the amorphous state of in vivo PHA can be explained by straightforward crystallization kinetics. 

A study of the phase behavior of (poly-f-butylmethacrylate)n - (polystyrene)n and (poly-t-butylacrylate)n - (polystyrene), miktoarm stars by differential scanning calorimetry has shown a remarkable decrease in the Tg of the polystyrene phase, in comparison with linear precursors, and an increase in the width of the glass transition [360]. An intermediate Tg was observed in some cases for microphase separated samples. The above phenomenon was attributed to an extended interphase region in these materials, due to partial mixing of the different chains around the cores of the stars. 

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