Heat capacity of dowanols within a temperature range of (275.15–339.15) K. Measurements and prediction

Abstract

The saturation heat capacities of seven dowanols, i.e. polyoxy(iso)propylene glycol mono-alkyl ethers (CnPm) and two dimethyl ethers; C1P1C1 and C1P2C1 were measured by the calorimetric (DSC) method. The measurements were performed within the temperature range of (275.15–339.15) K by means of a Micro DSCIII (Setaram) calorimeter. Assuming that the molar heat capacity (Cp,m) shows an additive character, the contributions to the Cp,m values of particular functional groups forming the compounds of CnPm series were calculated. Two models differing in the manner of molecule division into functional groups, i.e. first- and second-order additivity group contribution approach were used. In the latter, not only the type of functional group but also its position and the closest neighborhood were taken into account. The average relative deviations (ARD) between the experimental values of Cp,m and those estimated on the basis of the group contributions for the compounds of the series under investigation were calculated. Furthermore, the effect of hydrogen bond association on Cp,m values was also estimated and discussed.