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  • Author or Editor: G. Widmann x
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The simplen th order model equation combined with the Arrhenius approach of the temperature dependency of the reaction rate constant is widely used in thermal analysis.

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Abstract  

The DSC curve of succinonitrile shows a melting peak at approximately 60°C with the very small heat of fusion of 47 J/g. Further investigations in the low temperature range result in an additional exotherm at −60°C. On heating there are the two corresponding endotherms repeatably. We postulate a so called plastic crystalline mesophase between the two thermal effects.

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DSC purity determinations have become very popular today [3]. The latest edition of the Mettler software package for thermal analysis, TA72.S GraphWare, now comprises a powerful purity evaluation program. It is based on the simultaneous calculation of the mole ratio of the sum of the eutectic impurities, the melting point of the pure component, the melting point of the substance present and the linearization term. The portion of the melting curve investigated is selected appropriately.

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Abstract  

After a brief introduction of the terms supercooling, amorphous solid state, glass transition and devitrification, the known ways of production of amorphous solid water are discussed. DSC experiments with quench cooled aqueous solutions show the phenomenon of glass transition and devitrification.

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Abstract  

ADSC with its periodical temperature programs combines the features of DSC measured at high heating rate (high sensitivity) with those at low heating rate (high temperature resolution). In addition, the “reversing” cp effects can be separated from the “non-reversing” latent heat effects. Various periodical temperature programs can be applied. This paper compares the different possible temperature programs and their algorithms for the cp determination for metal, metal oxide and polymer of various properties. Simulated and measured results for various wave shapes and samples are presented. The relevant sample properties and their influence on the measurements are identified and guiding rules for the proper choice of the various experimental parameters are given. Measurements with different samples, performed with the new METTLER TOLEDO STARe-System, are shown and compared with the simulation results. The simulations and the measurements clearly show that the alternating techniques can yield new information about sample properties, but are susceptible to the proper choice of the various experimental parameters.

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A thermogravimetric unit is described having horizontal furnace arrangement, a temperature range of up to 1100°C and unsurpassed dynamic weighing range from 0 to 2 g at 0.1 μg resolution. Options of the system are sample robot, gas controller, high temperature furnace and hyphenated EGA techniques.

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