STUDY ON CRITICAL PHENOMENA IN POLYMER CRYSTALS BASED ON LIGHT-HEATING MODULATED TEMPERATURE DIFFERENTIAL SCANNING CALORIMETRY UNDER HIGH PRESSURE

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There had been no reports in the world, which strictly proved appearance of second-order phase transition in polymer crystals. We recently discovered the second-order phase transition in crystals of polyamide and vinylidene fluoride/trifluoroethylene copolymer on the basis of X-ray structure analysis under high-pressure. Through such studies, we found that the quantitative analysis had not been performed for specific-heat measurement under high-pressure in the world, which must give us one of the most important information to discuss the phase-transitional phenomena in material. It is the reason why we started this project.The object of this project is to construct the system to perform the quantitative and precise measurement of the specific heat of polymers by combining the high-pressure technique and light-heating modulated temperature differential scanning calorimeter (HP-LMTDSC system) as well as development of the phase-transitional study for some polymer crystals as-mentioned ab … More ove.In 2000, we tried to construct the basic HP-LMTDSC and examine the S/N characteristic with changing frequency, temperature and pressure to find that the maximum signal can be gained at 0. 1 Hz and the environmental medium affects the results. Temperature and pressure in the sample space was confirmed to be raised up to 300℃ and 300 Mpa.In 2001, we improved the system property. In order to change the incident light intensity sinusoidally, two polarizer plates were set, where one plate was fixed and the another rotated. Sensitivity of temperature measurement was increased by arranging seven Cu-constantan thermocouples in series.By using this system, pressure dependence of glass transition temperature Tg of atactic polystyrene was measured at 0.025 Hz and at 1-750 atm to find that Tg increased with pressure. The result shows that this system can be applied for various study under high pressure on polymers at molecular level such as crystal growth and melting, formation process of spherulite, electrical properties etc. Less