Adiabatic scanning calorimetry investigation of the melting and order–disorder phase transitions in the linear alkanes heptadecane and nonadecane and some of their binary mixtures

High resolution study of the n = 7–9 p,p’-n-alkylazobenzenes phase transitions by photopyroelectric and adiabatic scanning calorimetries

“…The only difference is that during the cooling run, unlike ASC, the PPE data are able to show the N-K2 transition, but not the K2-K1 one, indicating that PPE data are much less sensitive to enthalpy of transition. In this respect, it is worth reminding that a similar observation has been made in the study of phase transitions of alkanes by means of the combined use of ASC and PPE, where a specific transition between two different rotator phases could be observed only in the ASC data [37].…”

“…Fig. 3b shows the specific heat capacity data obtained by the PPE measurements, whose signal is much less sensitive to enthalpy of transition [37] than the ASC one. Hence, the effective c values obtained by PPE calorimetry over the observed first order phase transitions show much less pronounced peaks or none whatsoever.…”

“…As described in detail in Ref. [37], such thermistors were carefully calibrated in situ by means of a Tinsley Pt reference thermometer, previously calibrated by the National Physical Laboratory (UK). By means of such a procedure, an accuracy of ± 0.2 K could be obtained even if the precision and repeatability of the temperature reading was estimated to be of the order of the sub-millikelvin range.…”

“…As discussed in depth in Ref. [37,38], the ASC technique allows the absolute determination of both the specific heat and enthalpy of transition within an accuracy of 2 %, provided that uncertainty on the sample mass does not exceed this value. The validity of this assumption has been experimentally confirmed [38] by a statistical analysis of repeated measurements carried out on reference samples (biphenyl and phenyl salicylate), being the results in agreement within 2% with literature values.…”

Stability of Nano-Sized Aqueous Dispersion of n-Heptadecane to Thermal Cycling

“…Данный н-алкан обладает температурой плавления, близкой к комнатной (21,5 °C) и относительно высокой скрытой теплотой плавления (около 216 Дж/г), что говорит о перспективах его применения в отоплении и кондиционировании жилых помещений в составе ФПМ. Для н-гептадекана известен один переход в ротаторную фазу при нагреве в районе 11 °C [17,20].…”