Thermal stability evaluation of chemicals by DSC : Impact of crucible types and recommendation by ASTM E537‐24

Differential scanning calorimetry (DSC) measurements of chemical thermal stability are highly sensitive to test conditions, which can compromise data accuracy. In accordance with ASTM E537‐24, this study systematically evaluated the effects of crucible types and headspace gases (nitrogen vs. air) on DSC results, and elucidated the underlying mechanisms responsible for these effects. The results show that non‐sealed and pin‐holed crucibles lead to sample loss and distorted heat‐flow data, while air atmospheres introduce oxidative interference. High‐pressure gold‐plated crucibles meet the core requirements of ASTM E537‐24; however, their relatively large headspace and specific surface area of sample promote evaporation. To ensure data reliability, the ratio of total internal volume to sample volume must be kept at 5 or less, which, for certain energetic compounds, increases the risk of container rupture during the test. To overcome these limitations, a flame‐sealed glass capillary crucible (5 μL volume) was introduced, enabling precise and safe testing with minimal sample quantities. Validation using 2,4,6‐TNT confirmed that this approach achieves results in excellent agreement with theoretical values, and the method enhances both accuracy and safety. The study provides experimental guidance for optimizing DSC test conditions and improving the fidelity of thermal‐stability evaluations under ASTM E537‐24.