Thermal
Properties of Tristearin by Adiabatic and Differential Scanning
Calorimetry
J. Chem. Eng. Data, 50 (5), 1624 -1630, 2005.
Marija Matovic, J. Cees van Miltenburg, Jan Los, Francois G. Gandolfo
and Eckhard Flöter
Abstract:
The thermal behavior of tristearin was studied by adiabatic calorimetry
and differential scanning calorimetry (DSC). Specific heat capacities
of two polymorphic forms were measured in the adiabatic calorimeter,
where the -form was measured from 10 K to 370 K and the -form was
measured from 175 K to 370 K. The start of the measurement of the
stable -form from 10 K allowed the calculation of its entropy, so we
report the derived values of absolute entropy for the two forms of
tristearin at 298.15 K. The enthalpies of fusion and melting
temperatures for each polymorph were calculated from both the adiabatic
and the DSC experimental data and are compared to the literature
values. The values for the enthalpies of fusion of the stable -form are
in excellent agreement, being (221.6 ± 1) J·g-1 and
(219.6 ± 2) J·g-1 according to the adiabatic and DSC
measurements, respectively. The data for the -form are not in so good
agreement, which we attribute to the difficulty to crystallize this
phase in its pure form. Moreover, we examined the fleeting existence of
the '-form and its transformation to the -phase under isothermal
conditions.