Authors:B. Tong, Z. Tan, X. Lv, L. Sun, F. Xu, Q. Shi, and Y. Li
The molar heat capacities Cp,m of 2,2-dimethyl-1,3-propanediol were measured in the temperature range from 78 to 410 K by means of a small sample automated
adiabatic calorimeter. A solid-solid and a solid-liquid phase transitions were found at T-314.304 and 402.402 K, respectively, from the experimental Cp-T curve. The molar enthalpies and entropies of these transitions were determined to be 14.78 kJ mol−1, 47.01 J K−1 mol− for the solid-solid transition and 7.518 kJ mol−1, 18.68 J K−1 mol−1 for the solid-liquid transition, respectively. The dependence of heat capacity on the temperature was fitted to the following
polynomial equations with least square method. In the temperature range of 80 to 310 K, Cp,m/(J K−1 mol−1)=117.72+58.8022x+3.0964x2+6.87363x3−13.922x4+9.8889x5+16.195x6; x=[(T/K)−195]/115. In the temperature range of 325 to 395 K, Cp,m/(J K−1 mol−1)=290.74+22.767x−0.6247x2−0.8716x3−4.0159x4−0.2878x5+1.7244x6; x=[(T/K)−360]/35. The thermodynamic functions HT−H298.15 and ST−S298.15, were derived from the heat capacity data in the temperature range of 80 to 410 K with an interval of 5 K. The thermostability
of the compound was further tested by DSC and TG measurements. The results were in agreement with those obtained by adiabatic
Authors:F. Wilmet, N. Sbirrazzuoli, Y. Girault, and L. Elegant
The kinetic parameters of solid-plastic transitions on alcohols derived from neopentane were determined using differential scanning calorimetry (DSC) by a single or multiple scan analysis. The methods studied (Borchard-Daniels, Ellerstein, Multilinear law, Freeman-Carroll, Ozawa, Kissinger), never used before for that kind of transition, imply a single Arrhenius behaviour. These methods werre applied to 2,2-dimethyl 1-propanol (DP), 2,2-dimethyl 1,3-propanediol or neopentylglycol (NPG), 2-hydroxymethyl 2-methyl 1,3-propanediol or pentaglycerine (PG), and 2,2-dihydroxymethyl 1,3-propanediol or pentaerythritol (PE). A simple isothermal test is recommended to check the validity of activation energies experimentally obtained and Arrhenius frequency factors. Taking some restrictions on the heating rate for the heat evolution methods, the results are in agreement with the data obtained by isothermal tests. We have noted a linear dependence of the activation energy values on the number of hydroxyl groups with the exception of pentaerythritol. Isothermal simulations of the solid-plastic transition are an example of industrial applications.