Thermal analysis and dilatometry of glasses formed under elevated pressure
Thermal analysis and dilatometry of glasses formed under elevated pressure
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高压下形成的玻璃的热分析和膨胀测定
DOI：
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发表时间：
1974
期刊：
影响因子：
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通讯作者：
B. Wunderlich
中科院分区：
文献类型：
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作者：
A. Weitz;B. Wunderlich
在环境压力下，通过热分析和折光率测定法研究了通过在高达517 MN/m2的高压下以5°C/hr冷却从液态形成的致密玻璃。研究的材料是聚苯乙烯，聚（甲基丙烯酸甲酯），酚酞，蔗糖，和1：1的混合物，按重量计的钾和硝酸钙。发现致密化玻璃的焓比在大气压下形成的玻璃的焓高2-6 J/g。发现加热致密化玻璃时的主要焓和体积弛豫不相关。对于在各种压力下冷却的所有玻璃，玻璃化转变区的温度上限保持恒定，而聚合物玻璃的温度下限随着压力的增加而降低至55°C。数据的解释表明，一个额外的，显着的体积松弛发生在减压在室温下的所有玻璃分析。
Densified glasses, formed from the liquid state by cooling at 5°C/hr under elevated pressures of up to 517 MN/m2, were studied by thermal analysis and dilatometry at ambient pressure. The materials studied were polystyrene, poly(methyl methacrylate), phenolphthalein, sucrose, and a 1 : 1 mixture by weight of potassium and calcium nitrate. Enthalpies of the densified glasses were found to be up to 2–6 J/g greater than the enthalpies of the glasses formed at atmospheric pressure. The major enthalpy and volume relaxation on heating the densified glasses was found to be not correlated The upper temperature limit of the glass-transition region remained constant for all glasses cooled at various pressures, while the lower temperature limit of the polymeric glasses decreased up to 55°C with increasing pressure. The interpretation of the data suggests that an additional, significant volume relaxation occurred on depressurization at room temperature for all glasses analyzed.