Abstract Fast scanning calorimetry (FSC) enables to prevent the crystallization of many low-molecular-mass organic compounds. In spite of extremely high cooling rates accessible by fast scanning calorimetry, limitations remain on the measurements of rapidly crystallizing and volatile compounds in the supercooled liquid state. We developed a new method for heat capacity determination, which requires measuring the heat flow rates only on cooling at one fixed scanning rate of a number of samples of different mass. The molar heat capacity is derived from the slope of the heat flow rates plotted against the sample amount, divided by the cooling rate. The total uncertainty of the method was determined to 5 %. The validity was confirmed using benzophenone as a reference compound. Then this approach was applied to study the heat capacity of 9,9′-bifluorenyl in the supercooled liquid state between 350 and 550 K; respective values were obtained for the first time. The relationship between the fusion enthalpy of 9,9′-bifluorenyl at Tm and solution enthalpy in benzene at 298.15 K was analyzed using combination of Hess’s and Kirchhoff’s laws of thermochemistry. Consistency between the thermochemical data derived independently by solution, fast scanning, and differential scanning calorimetry was established and confirmed the validity of the new method for heat capacity determination by FSC.

中文翻译：

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一种使用快速扫描量热法测定过冷液态热容的新方法：9,9'-二芴基的热化学研究

摘要 快速扫描量热法 (FSC) 能够防止许多低分子量有机化合物的结晶。尽管快速扫描量热法可以获得极高的冷却速率，但在过冷液态下快速结晶和挥发性化合物的测量仍然存在局限性。我们开发了一种新的热容量测定方法，该方法需要测量多个不同质量样品的固定扫描速率下冷却时的热流率。摩尔热容是根据热流率对样品量绘制的斜率除以冷却率得出的。该方法的总不确定度被确定为 5%。使用二苯甲酮作为参考化合物确认了有效性。然后将这种方法应用于研究 9 的热容量，9'-二芴基在 350 和 550 K 之间处于过冷液态；各自的值是第一次获得。结合赫斯定律和基尔霍夫热化学定律，分析了 9,9'-二芴基在 Tm 下的融合焓与在 298.15 K 下苯中的溶液焓之间的关系。建立了由溶液、快速扫描和差示扫描量热法独立得出的热化学数据之间的一致性，并证实了 FSC 热容测定新方法的有效性。