Jpn. J. Appl. Phys. 12 (1973) pp. 1143-1151 |Next Article| |Table of Contents|
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A Two-Layer Slab Method for Measuring Thermal Diffusivity of Polymer by Irradiated Light Heat-Wave. I.
Faculty of Engineering, Tokyo Institute of Technology
(Received July 30, 1971)
A two-layer slab method is developed for determining the thermal diffusivity of polymer with the modulated light heat source. A solution of heat transfer equation is obtained for an infinitely wide two-layer slab, and the expression for the temperature-wave phase shift is given. The use of phase shift measurement avoids some of the problems associated with temperature measuring instrumentation of polymer. Measurement is possible even at a softening temperature because one of two layers in a slab plays the role of a mechanical holder. An analysis of energy loss at the back surface indicates that experiment should be feasible even when losses are so large. An abrupt change of thermal diffusivity at about 50°C higher than the glass temperature as well as the well known abrupt change at the glass temperature, is obtained in as well as the polystyrene, polymethacrylate, and nylon 6.
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