| Summary: | 碩士 === 長庚大學 === 化工與材料工程學系 === 106 === The purpose of this study is to prepare the PP particle and the hot pressed PP thin slice foaming material by supercritical carbon dioxide. We expect that the PP particle and the hot pressed PP thin slice to use the supercritical carbon dioxide treatmenting can make the PP particles and the hot pressed PP thin slice have appropriate average cell diameter according to different requirements, further to get the microporous foamed material of PP, and the thermal properties of the PP particles and the hot pressed PP thin slice are improved. The operating conditions such as foaming temperature, pressure, foaming time, depressurization time, influence on the structure of the foam and changes in glass transition temperature, melting point, crystallinity, and thermal stability before and after foaming were investigated. The SEM image shows that the temperature of 150 °C is the lowest foaming condition. As the temperature rises, the average cell diameter will become larger. As the pressure increases, the average cell diameter of the foamed PP particles will become larger , the average cell diameter of the foamed hot-pressed PP thin slice becomes smaller, as the foaming time increases, the average cell diameter of the foaming PP particle and the foaming hot pressed PP thin slice becomes smaller, As the depressurization time increases, the average cell diameter of the foaming PP particles becomes smaller, and the average cell diameter of the foamed hot pressed PP thin slice becomes larger. The result of DSC shows that after the supercritical carbon dioxide foaming, the crystallinity of PP particles is higher than that before unfoaming , and the crystallinity of hot pressed PP thin slice is lower than that before unfoaming. The result of DSC shows that after supercritical carbon dioxide foaming, the degradation temperature of PP particles is lower than that before unfoaming, and the 5wt% thermogravimetric loss temperature is higher than that before unfoaming, the degradation temperature of hot pressed PP thin slice is higher than that before unfoaming , the 5wt% thermogravimetric loss temperature is lower than that before unfoaming.
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