Differential scanning calorimetry system

The DSC thermogram of chlorpromazine hydrochloride shown in Figure 2 was obtained using Du Pont model 9900 differential scanning calorimetry system, using a sample size of 2.83 mg and a heating rate of 10°C/minute [13]. 

Figure 1. Differential Scanning Calorimetry System 1—Hoke...

The expoimental methods of measuring transition temperatures, wh her for crystal to mesophase, mesophase to mesophase, or mesophase to isotropic liquid, fall into four categories. A high pressure cell with optical detection is a common method [1,2]. High pressure diff ential thermal analysis (DTA) systems have been built [3]. In some cases DTA has been combined with optical cells for visual as well as thermal detection [4]. A variation of thermal detection of phase transitions is the high pressure differential scanning calorimetry system [5]. The technique that provides pVT data is based on measuring volume or density as a function of pressure for various isotherms [6-10]. A unique method is based on the thermobarometer developed by Busine [11]. 

The cure of novolaks with hexa has been studied with differential scanning calorimetry (dsc) and torsional braid analysis (tba) (46) both a high ortho novolak and a conventional acid-cataly2ed system were included. The dsc showed an exothermic peak indicating a novolak—hexa reaction ca 20°C higher than the gelation peak observed in tba. Activation energies were also calculated. 

Differential scanning calorimetry (DSC) is fast, sensitive, simple, and only needs a small amount of a sample, therefore it is widely used to analyze the system. For example, a polyester-based TPU, 892024TPU, made in our lab, was blended with a commercial PVC resin in different ratios. The glass transition temperature (Tg) values of these systems were determined by DSC and the results are shown in Table 1. 

The various terms appearing in these equations are self-evident. The differential heat release, dkidt, data are computed from differential scanning calorimetry (DSC). A typical DSC isotherm for a polyurethane reactive system appears in Fig. 11. Energetic composite processing is normally conducted under isothermal conditions so that Eq. (15) is more applicable. 

Many papers deal with the crystallization of polymer melts and solutions under the conditions of molecular orientation achieved by the methods described above. Various physical methods have been used in these investigations electron microscopy, X-ray diffraction, birefringence, differential scanning calorimetry, etc. As a result, the properties of these systems have been described in detail and definite conclusions concerning their structure have been drawn (e.g.4 13 19,39,52)). 

The differential scanning calorimetry (DSC) thermogram of miconazole was obtained using a DuPont 2100 thermal analyzer system. The thermogram shown in Fig. 2 was obtained at a heating rate of 10°C/min and was run over the range 50—300 °C. Miconazole was found to melt at 186.55 °C. 

Measurements of differential scanning calorimetry (DSC) were obtained on a TA Instruments 2910 thermal analysis system (Fig. 2). Samples of approximately 1-2 mg were accurately weighed into an aluminum DSC pan, and covered with an aluminum lid that was crimped in place. The samples were then heated over the range of 20-140 °C, at a heating rate of 10 °C/min. Valproic acid was found to boil at 227 °C. 

Rytter et al. reported polymerizations with the dual precatalyst system 14/15 in presence of MAO [30]. Under ethylene-hexene copolymerization conditions, 14/MAO produced a polymer with 0.7 mol% hexene, while the 15/MAO gave a copolymer with ca. 5 mol% hexene. In the mixed catalyst system, the activity and comonomer incorporation were approximate averages of what would be expected for the two catalysts. Using crystallization analysis fractionation (CRYSTAF) and differential scanning calorimetry (DSC) analysis, it was concluded in a later paper by Rytter that the material was a blend containing no block copolymer [31],... 

Differential scanning calorimetry (DSC) compares the two different heat flows one to or from the sample to be studied, the other to or from a substance with no phase transitions in the range to be measured e. g. glassmaking sand. Figure 1.45 is the scheme of a DSC system Fig. 1.46 is a commercial apparatus for DSC measurements. 

Richardson, S.J. 1989. Contribution of proton exchange to the oxygen-17 nuclear magnetic resonance transverse relaxation rate in water and starch-water systems. Cereal Chem. 66, 244-246. Richardson, M.J. and Saville, N.G. 1975. Derivation of accurate glass transition temperatures by differential scanning calorimetry. Polymer 16, 753-757. 

Dynamic mechanical anlaysis (DMA) measurements were done on a Rheometrics RDS-7700 rheometer in torsional rectangular geometry mode using 60 x 12 x 3 mm samples at 0.05% strain and 1 Hz. Differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and thermogravimetric analysis (TGA) were performed on a Perkin-Elmer 7000 thermal analysis system. 

C. T. Mortimer. Differential Scanning Calorimetry. In Thermochemistry and Its Applications to Chemical and Biochemical Systems M. A. V Ribeiro da Silva, Ed. NATO ASI Series C, Riedel Dordrecht, 1984 47-60. 

Sturtevant, J.M. 1980. Differential scanning calorimetry processes involving proteins. In Bioenergetics and Thermodynamics Model Systems. A. Braibanti, editor. John Wiley Sons, New York, 391-396. 

Stevens, D. J. and Elton, G. A. H. (1977). Thermal properties of starch/water system. Part I. Measurement of heat of gelatinization by differential scanning calorimetry. Die Starke 23, 8-11. 

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