高分子材料の温度伝導率の異方性に関する研究 : 第3報,溶融非定常流動場での過渡的特性

概要

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Previously, in the 1st report, we investigated the anisotropy of the thermal diffusivity of molded PMMA samples. In the 2nd report, anisotropic behavior of molten PS polymer in steady flow was investigated with various shear rates. It was confirmed that the anisotropy of the thermal diffusivity was caused by the molecular orientation in the shear flow region. In the present paper, the anisotropy of thermal diffusivity under a transient state in the case of sudden loading or unloading of the shear stress was measured by the forced Rayleigh scattering method used in the previous reports. It was shown that "overshoot" phenomenon of thermal diffusivity took place under sudden loading of shear stress and the "relaxation" phenomenon of molecular orientation was observed in the case of stress unloading. The transient values of thermal diffusivity in the direction parallel to the flow, and those perpendicular to the flow, were dependent on the initial temperature and the magnitude of the shear stress.
1993-10-25