Construction of a top-loading adiabatic calorimeter equipped with a refrigerator

Abstract

A top-loading type adiabatic calorimeter equipped with a refrigerator, which functions in the temperature range of 20–300 K, is developed. Since the refrigerator is built in, measurements can be conducted without replenishing liquid nitrogen or liquid helium; this, in addition to the top-loading type calorimeter features, reduces the time required to set the sample by 10 min. The heat capacity of benzoic acid, used as a standard sample for heat capacity measurement, is measured to evaluate the device performance. The heat capacity measurement imprecisions were ±0.8 % at 20–50 K, ± 0.3 % at 50–130 K, and ±0.2 % at above 130 K. The inaccuracies of the heat capacity from the benzoic acid measurement results were ±1.1 % at 20–100 K and ±0.9 % at 100–300 K. These performance results are the same for any traditional adiabatic calorimeter considering the heat capacity ratio between the sample and the cell. Using this device, the molecular-weight dependence of the heat capacity of the styrene oligomer in the solid state is measured and the effect of the end groups on the heat capacity is investigated. It is suggested that the influence of the end group on the heat capacity disappeared rapidly as the molecular weight increased.