Pentaerythritol (2,2-bis-[hydroxymethylene]-l,3-propanediol) is odorless, white, crystalline compound. It usually crystallises in the tetragonal form. At temperatures above 180~ it undergoes a transition from the tetragonal form to a cubic lattice structure. Various melting points have been reported for pure pentaerythritol, with 261-262~ most often mentioned. On heating pentaerythritol sublimes and boils -the temperature dependencies of its vapour pressure have been reported [ 1,2].Owing to such properties, the thermoanalytical curves of pentaerythritol (e.g. TG, DTA or DSC) are strongly affected by the conditions of measurement. Specifically, factors like the heating rate, sample mass, geometry of sample system (sample pan -whether standard or hermetically sealed etc.), purge gas flow rate, the sample grain size distribution and, optionally, the sample dilution are of importance.The purpose of the present note is to demonstrate the effect of the measurement conditions on the thermal behavior of the sample. With this regard some unusual DSC experiments were performed: in these experiments the sample was not encapsulated, but simple placed in an open sample container. These measurements were carried out in order to study the sublimation behavior of pentaerythritol. In addition, the interpretation given in Ref. [3] has been attempted. Figure 1 shows DSC curves recorded for pure pentaerythritol, from Fluka AG, using the Mettler TA4000/DSC30 heat-flux differential scanning calorimeter under constant flow of argon (100 ml min-~), at heating rates of 0.5 and 10~ min -I, for sample masses of about 0.5, 2 and 13 rag, in an AI, 40 I.tl pan,
