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Journal of Thermal Analysis and Calorimetry
Authors: A. Hadj-Sahraoui, A. Tahir, G. Louis, and P. Peretti

Abstract  

Analysis of the photoacoustic signalvs. the modulation frequency allows the determination of thermal diffusivity. Computer simulations have been carried out to determine the optimal conditions, in the case of rear surface illumination, for which the thermal diffusivity is accurately measured. In accordance with these conditions, measurements were performed on a reference sample (silicon).

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Abstract  

The paper describes a new transient hot wire instrument which employs 25.4 μm diameter tantalum wire with an insulating tantalum pentoxide coating. This hot-wire cell with a thin insulating layer is suitable for measurement of the thermal conductivity and the thermal diffusivity of electrically conducting and polar liquids. This instrument has been used for experimental measurement of the thermal conductivity and the thermal diffusivity of poly(acrylic acid) solution (50 mass%) in the temperature range of 299 to 368 K at atmospheric pressure. The thermal conductivity data is estimated to be accurate within ±4%. Thermal diffusivity measurements have a much higher uncertainty (±30%) and need further refinement.

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Abstract  

We have developed a laser flash apparatus for simultaneous measurements of thermal diffusivity and specific heat capacity of solid materials by introducing recent technical progress: uniform heating by a homogenized laser beam using an optical fiber with a mode mixer, measuring transient temperature of a specimen with a calibrated radiation thermometer, analyzing a transient temperature curve with a curve fitting method, to achieve differential laser flash calorimetry. Thermal diffusivity, specific heat capacity and thermal conductivity of glassy carbon and molybdenum were measured in the temperature range from 300 to 1100 K.

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The thermal diffusivity and thermal conductivity of the zirconate, cerate and uranate of barium were investigated by employing the laser flash technique. The variation in the thermal resistivity as a function of temperature was examined and the heat transport behaviour of these materials is discussed.

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Abstract  

Thermal diffusivity of high density polyethylene (PE) has been measured by a new a. c. Joule-heating method. The diffusivity was determined at various temperatures between room temperature and above melting point in heating and cooling processes. This method is based on the phase shift of temperature waves across film sample, so that it offers several advantages, e.g., easy measuring in polymer melts.

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Progress in Agricultural Engineering Sciences
Authors: Monika Božiková, Peter Hlaváč, Vlasta Vozárová, Zuzana Hlaváčová, Ľubomír Kubík, Peter Kotoulek, and Ján Brindza

. , Maye , J. P. , Martemianov , S. ( 2012 ). A new transient two-wire method for measuring the thermal diffusivity of electrically conducting and highly corrosive liquids using small samples . International Journal of Thermophysics, vol. 29 ( 4

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Abstract  

One of the benefits of temperature-modulated DSC (TMDSC) is its ability to measure thermal conductivity and thermal diffusivity without DSC cell modifications or additional accessories. Thermal conductivity of solid materials from 0.1 to about 1 W m-1 K-1 measured. Applications of this approach have been discussed in the literature but no description is yet available concerning the derivation of the working equations. This presentation provides a detailed derivation of the working equations used to obtain thermal conductivity and thermal diffusivity from TMDSC data.

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Thermal diffusivity and heat conductivity are important properties for description of the heat transport in solids.

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Abstract  

A new sensitive thermal analysis for the observation of re-orientation behavior in the melting region of the ultradrawn poly(ethylene) film was proposed by the simultaneous measurement of thermal diffusivity and birefringence under optical microscope in a constant heating rate. Thermal diffusivity was obtained by the phase delay of temperature wave passed through the thickness direction of the specimen. The results correspond with each other over wide temperature range including melting temperature. It was concluded that the thermal diffusivity measurement was more sensitive not only to detect the molecular relaxation in a continuous heating run, but also to find out the delicate variation of chain direction.

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