Differential scanning calorimetry 392 INDEX

Differential scanning calorimetry Limiting oxygen index w-Cresol... 

A range of heterocyclic azides were studied by differential scanning calorimetry, the enthalpies of thermal decomposition were lower than might have been expected, from 0.3—1 kJ/g. If ortho substituents onto which the azide could cyclise were present, decomposition enthalpies were, as one would expect, lower still [5], as well as the individually indexed compounds ... 

Most of the physical properties of the polymer (heat capacity, expansion coefficient, storage modulus, gas permeability, refractive index, etc.) undergo a discontinuous variation at the glass transition. The most frequently used methods to determine Tg are differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical thermal analysis (DMTA). But several other techniques may be also employed, such as the measurement of the complex dielectric permittivity as a function of temperature. The shape of variation of corresponding properties is shown in Fig. 4.1. 

Index Entries Escherichia coli polyhydroxyalkanoates fed-batch fermentation nuclear magnetic resonance differential scanning calorimetry. 

Tan, C. P., Che Man, Y. B., Selamat, J., and Yusoff, M. S. A. 2002. Comparative Studies of Oxidative Stability of Edible Oils by Differential Scanning Calorimetry and Oil Stability Index Methods. Food Chem., 76,385-389. 

Many relatively slow or static methods have been used to measure Tg. These include techniques for determining the density or specific volume of the polymer as a function of temperature (cf. Fig. 11-1) as well as measurements of refractive index, elastic modulus, and other properties. Differential thermal analysis and differential scanning calorimetry are widely used for this purpose at present, with simple extrapolative eorrections for the effects of heating or cording rates on the observed values of Tg. These two methods reflect the changes in specific heat of the polymer at the glass-to-rubber transition. Dynamic mechanical measurements, which are described in Section 11.5, are also widely employed for locating Tg. 

Tg can be measured by dilatometry, refractive index, differential scanning calorimetry, dynamic mechanical methods and by dielectric relaxation techniques. 

Table III gives the physical and chemical properties of the M. oleifera oil. Some of the properties of the oil depend on the extraction medium. The M oleifera oil is liquid at room temperature and pale-yellow in colour. Electronic nose analysis shows that it has a flavor similar to that of peanut oil. The melting point estimated by differential scanning calorimetry is 19°C (15). The chemical properties of the oil depicted in Table III below are amongst the most important properties that determines the present condition of the oil. Free fatty acid content is a valuable measure of oil quality. The iodine value is the measure of the degree of unsaturation of the oil. The unsaponifiable matter represents other lipid- associated substances like, sterols, fat soluble vitamins, hydrocarbons and pigments. The density, iodine value, viscosity, smoke point and the colour of Moringa oil depends on the method of extraction, while the refractive index does not. Varietal differences are significant in all physical characteristics apart from refractive index and density (2). The heating profile of the M. oleifera seed oil using the differential scanning calorimetry (DSC) conventional scan rate shows that there is one major peak B and, two small shoulder peaks A and C...

The morphology of the materials must also be important. Large changes in creep were found for very small changes in the degree of crystallinity as measured by x-ray techniques or by differential scanning calorimetry (DSC). This is apparent from a comparison of the creep data with data on crystallinity index and apparent heat of fusion (Table I). The crystallinity index is the area above the amorphous curve divided by the total area obtained from an... 

Differential Scanning Calorimetry Heats of Solution Refractive Index Surface Tension Viscosity... 

Krause, S., Lu, Z.-H., and Iskander, M., Rroperties of low molecular weight block copolymers 4. Differential scanning calorimetry and refractive index-temperature measurements on styrene-butadiene diblock copolymers and styrene-butadiene-styrene triblock copolymers. Macromolecules, 15,1076-1082 (1982b). 

T. Ocher changes occur at this temperature that can be monitored to identify the T experimentally. These include changes in specific volume of the polymer, index of refraction, gas diffusion coefficients, thermal expansion coefficients (measured by dilatomeCry), and specific heat (measured by differential scanning calorimetry (DSC) or by differential thermal analysis (DTA)). General discussions of the elastic properties of polymers can be found in references (4.2)-... 

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