ISSN:
1435-1536
Keywords:
thermal diffusivity
;
polymer foils
;
drawn foils
;
photoacoustic method
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract A nonstationary method to measure the thermal diffusivity of polymer foils with thicknesses between 10 and 40μm normal to the foil plane is described. The principle of the experimental technique is a modification of the photoacoustic effect. The quantity that is measured, is the phase angle between the modulation of the light intensity and the pressure variation as a function of frequency. A theoretical treatment of the phenomenon is presented which enables the evaluation of the diffusivity from the experimental data. It is possible to measure absolute values of the thermal diffusivity with an accuracy in the order of three percent and relative changes in the thermal diffusivity, e. g. by drawing, of one percent. Measurements were performed on commercial PETP foils of 19 and 30μm thickness drawn along various directions. For draw ratios up to 1.3 the diffusivity decreased about 20 percent or increased about 10 percent, depending on the foil thickness and the treatment during manufacture. The results can be interpreted with the aggregate model of Kilian and Pietralla as well as with the two-phase model of Choy and Young.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01413937
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