Open AccessDetermination of crystallization enthalpies of some organic peroxides by a differential isothermal calorimeter
Author(s) -
V. V. Sergeev,
G. V. Melnyk,
В. Б. Вострес,
P Pavlovskii,
С. І. Герасимчук
Publication year - 2021
Publication title -
voprosy himii i himičeskoj tehnologii/voprosy himii i himičeskoj tehnologii
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.278
H-Index - 7
eISSN - 2413-7987
pISSN - 0321-4095
DOI - 10.32434/0321-4095-2021-135-2-90-94
Subject(s) - ampoule , crystallization , supercooling , enthalpy of vaporization , enthalpy , sublimation (psychology) , enthalpy of fusion , thermodynamics , differential scanning calorimetry , calorimeter (particle physics) , chemistry , vaporization , enthalpy of sublimation , materials science , organic chemistry , psychology , physics , detector , electrical engineering , psychotherapist , engineering
We developed a method for determination of the crystallization enthalpy of organic substances in a heat-conducting calorimeter at a temperature close to 298 K. Crystallization was conducted in the MID-200 calorimeter using an ampoule technique. The volume of ampoules, which contain the supercooled liquids, was approximately 0.2 cm3. The residual pressure was 650 Pa to lessen the heat loss. A few crystals of the material under investigation were employed as the crystallization centers. Based on the results of the experiment, the crystallization enthalpies of dicumyl peroxide, peroxyoctanoic acid and di-tert-butylperoxy isophthalate were determined. The vaporization and sublimation enthalpies of peroxyoctanoic acid were assessed using an ampoule method in the calorimeter. It was established that dicumyl peroxide which was supercooled 14 K below the fusion temperature exhibited a 20% increase in crystallization enthalpy as compared with that calculated from the difference between vaporization and sublimation enthalpy. At the same time, the crystallization enthalpy of peroxyoctanoic acid supercooled by 5 K was equal to that calculated from the difference between vaporization and sublimation enthalpy within the limiting experimental error. The received data show that the proposed method is promising for determining the heat of crystallization of liquids that are able to exist in a supercooled state during some time.