LOCAL RADIATION HEATING TECHNIQUE OF POLYMERIC MATERIALS USING FUNCTIONAL-DYE

摘要

In this study, the authors added a functional dye to a material which was transparent in initial state, to locally change the radiation absorption coefficient of the material. By using this material, we proposed a radiation heating technique that can achieve a selective local heating in three-dimensional system and investigated its feasibility. Temperature change of the test sample was measured in the experiment, and the characteristic of the presenting technique was investigated. To obtain better understanding of the presenting technique, numerical simulation of the temperature distribution inside the sample was also performed. In the experiment, photochromic dye and thermochromic dye were used as functional dyes and they were individually added to thermoplastic polymeric material (polystyrene) by using organic solvent (tetrahydrofuran). Then the material containing the dye was dried and processed to give a certain shape for the experiment. He-Cd laser and Ar ion laser were properly used as the excitation and the heat sources according to the type of dye. Experimental result showed that local heating of the material was achieved only in quite thin surface region in case of photochromic dye. On the other hand, local heating inside the material was successfully achieved in case of thermochromic dye. However, it was also observed that the heating point was moved to the upstream direction of the laser beam. To examine the solution of Ms problem, effect of the laser irradiation conditions on the moving speed of the heating point was discussed based on the numerical simulation results.