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The heat capacities of d-ribose and d-mannose have been studied over the temperature range from 1.9 to 440 K for the first time using a combination of Quantum Design Physical Property Measurement System and a differential scanning calorimeter. The purity, crystal phase and thermal stability of these two compounds have been characterized using HPLC, XRD and TG–DTA techniques, respectively. The heat capacities of d-Mannose have been found to be larger than those of d-ribose due to its larger molecular weight, and the solid–liquid transition due to the sample melting has also been detected in the heat capacity curve. The heat capacities of these two compounds have been fitted to a series of theoretical models and empirical equations in the entire experimental temperature region, and the corresponding thermodynamic functions have been derived based on the curve fitting in the temperature range from 0 to 440 K. Moreover, the phase transition enthalpy and melting temperature of these two compounds have also been determined from the heat flows obtained in DSC measurements.

The kinetics of the glass transition of Zr 57.2 Al 21.4 Ni 21.4 bulk metallic glass (BMG) was studied using differential scanning calorimetry (DSC) with continuous heating of the sample at various heating rates. The heating rate dependence of the glass transition temperature ( T g ) was investigated. By employing Moynihan and Kissinger models, the activation energy ( E ) of the glass transition was determined. It was shown that the transition process cannot be described in terms of single activation energy. The variation of E with the extent of conversion ( α ) was further analyzed by using two isoconversional methods (Kissinger–Akahira–Sunose method and Vyazovkin method). Evidence of the variation of E throughout the glass transition region was observed, which indicated that the transformation from amorphous to a supercooled liquid phase of Zr 57.2 Al 21.4 Ni 21.4 BMG was a complex process.

The crystallization kinetics of the bulk amorphous Cu58.1Zr35.9Al6 alloy was examined by differential scanning calorimetry under continuous heating and isothermal annealing. During continuous heating, the activation energy of crystallization was determined to be 383 kJ/mol by Kissinger method. However, on the isothermal annealing, the activation energy was determined to be 459.2 kJ/mol by the Arrhenius method, which was much larger than that obtained from the Kissinger method. The different temperatures at which crystallization occurs are responsible for the discrepancy in the activation energy. The average Avrami exponent of about 3.5 implies that the crystallization process of the bulk amorphous Cu58.1Zr35.9Al6 alloy is diffusion-controlled with a nucleation rate decreasing with time.

The low-temperature heat capacity Cp,m of erythritol (C4H10O4, CAS 149-32-6) was precisely measured in the temperature range from 80 to 410 K by means of a small sample automated adiabatic calorimeter. A solid-liquid phase transition was found at T=390.254 K from the experimental Cp-T curve. The molar enthalpy and entropy of this transition were determined to be 37.92±0.19 kJ mol−1 and 97.17±0.49 J K−1 mol−1, respectively. 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 standard molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined: ΔcHm0(C4H10O4, cr)= −2102.90±1.56 kJ mol−1 and ΔfHm0(C4H10O4, cr)= − 900.29±0.84 kJ mol−1, by means of a precision oxygen-bomb combustion calorimeter at T=298.15 K. DSC and TG measurements were performed to study the thermostability of the compound. The results were in agreement with those obtained from heat capacity measurements.

A calorimetric study and thermal analysis for 8-hydroxyquinoline were performed. The low-temperature heat capacity of this compound was measured with a precise automated adiabatic calorimeter over the temperature range from 78 to 370 K. The melting point T(fus), molar enthalpy Delta(fus)H(m) and molar entropy Delta(fus)S(m) of fusion of this substance were determined to be (345.74 +/- 0.15) K, (13.93 +/- 0.11) kJ center dot mol(-1) and (40.26 +/- 0.33) J center dot K(-1)center dot mol(-1), respectively. The thermodynamic functions of the substance, such as molar enthalpy and entropy of fusion, and thermodynamic functions [H(T)-H(298.15)] and [S(T)-S(298.15)] were derived from two polynomial equations of the experimental molar heat capacities against the reduced temperature fitted by the least square method. The melting temperatures for the sample and the absolutely pure compound have been obtained from fractional melting experiments to be 345.601 and 345.761 K, respectively, and the molar fraction purity of the sample was calculated to be 0.9978 according to the van't Hoff equation. The thermal stability of the compound was further investigated by differential scanning calorimetry (DSC).

The low-temperature heat capacities of 1-hexadecanol have been measured with an automatic adiabatic calorimeter over the temperature range from 80 to 370 K. A solid-liquid phase transition was observed at T-m=322.225 +/- 0.002 K and the molar enthalpy and entropy of fusion were determined to be 57.743 +/- 0.008 kJ mol(-1) and 179.19 +/- 0.04 J K-1 mol(-1), respectively. The purity, the real melting point (T-1) and the ideal melting point without any impurity or absolutely purity (To) of the sample under investigation were determined to be 99.162 mol%, 322.21 and 322.34 K, respectively, by fractional melting method. According to the polynomial equation of heat capacity and thermodynamic relationship, the thermodynamic functions of the compound relative to the reference temperature 298.15 K were calculated in the temperature ranges of 80 to 370 K with an interval of 5 K. In addition, further researches of thermal properties for this compound were carried out by means of TG/DTG.

The low-temperature heat capacity C p,m of erythritol (C 4 H 10 O 4 , CAS 149-32-6) was precisely measured in the temperature range from 80 to 410 K by means of a small sample automated adiabatic calorimeter. A solid-liquid phase transition was found at T=390.254 K from the experimental Cp-T curve. The molar enthalpy and entropy of this transition were determined to be 37.92±0.19 kJ mol -1 and 97.17±0.49 J K -1 mol -1 , respectively. The thermodynamic functions [H T -H 298.15 ] and [S T -S 298.15 ], were derived from the heat capacity data in the temperature range of 80 to 410 K with an interval of 5 K. The standard molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined: Δ c H 0 m(C 4 H 10 O 4 , cr)=-2102.90±1.56 kJ mol -1 and Δ f H 0 m [(C 4 H 10 O 4 , cr)=- 900.29±0.84 kJ mol -1 , by means of a precision oxygen-bomb combustion calorimeter at T=298.15 K. DSC and TG measurements were performed to study the thermostability of the compound. The results were in agreement with those obtained from heat capacity measurements.

Heat capacity c-p.m of 1-docosanol was precisely measured in the temperature range from 78 to 400 k by means of an automated adiabatic calorimeter. the dependence of heat capacity on the temperature was fitted to polynomial equations with least square method. the melting temperature, molar enthalpy, and molar entropy of fusion were determined to be 340.844 k, 85.07 kj center dot mol(-1), and 249.6 j center dot k-1 center dot mol(-1), respectively. the thermodynamic functions, [h-1-h-298.15 and [s-t-s-298.15], were derived from the thermodynamic equations in the temperature range from 80 to 400 k with an interval of 5 k. the thermostability of the compound was further investigated by dsc and tg techniques from 400 to 900 k.

Low-temperature heat capacity C-p.m of 2-amino-5-nitropyridine (C5H5N3O2; CAS 4214-76-0) was measured in the temperature range from 80 to 396 K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The thermodynamic functions [HT - H298.1-5] and [S-T - S-298.15] were calculated in the range from 80 to 395 K based on the heat capacity data. The standard molar energy and standard molar enthalpy of combustion have been determined, Delta U-c (C5H5N3O2, s) = -(2676.26 +/- 0.24) U mol(-1) and Delta H-c(m)degrees (C5H5N3O2, s) = -(2673.16 +/- 0.24) U mol(-1), by means of a precision oxygen-bomb combustion calorimeter at T= 298.15 +/- 0.001 K. The standard molar enthalpy of formation has been derived, Delta H-f(m)degrees, (C5H5N3O2, s) = -(8.97 +/- 0.99) kJ mol(-1), from the standard molar enthalpy of combustion in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle. The thermodynamic properties were further investigated through differential scanning calorimeter (DSC) and the thermogravimetric (TG) analysis. (C) 2007 Elsevier B.V. All rights reserved.

The low-temperature heat capacity C p , m 0 of xylitol was precisely measured in the temperature range from 80 to 390 K by means of a small sample automated adiabatic calorimeter. A solid–liquid phase transition was found from the experimental Cp–T curve in the temperature range 360–375 K with the peak heat capacity at 369.04 K. The dependence of heat capacity on the temperature was fitted to the following polynomial equations with least square method. In the temperature range of 80–360 K, C p , m 0 ( J K − 1 mo l − 1 ) = 165.87 + 105.19 x + 1.8011 x 2 − 41.445 x 3 − 41.851 x 4 + 65.152 x 5 + 66.744 x 6 , x = [ T ( K ) − 220 ] / 140 . In the temperature range of 370–390 K, C p , m 0 ( J K − 1 mo l − 1 ) = 426.19 + 5.6366 x , x = [ T ( K ) − 380 ] / 10 . The molar enthalpy and entropy of this transition were determined to be 33.26 ± 0.17 kJ mol−1 and 90.12 ± 0.45 J K−1 mol−1, respectively. The standard thermodynamic functions ( H T 0 − H 298.15 0 ) and ( S T 0 − S 298.15 0 ) , were derived from the heat capacity data in the temperature range of 80 to 390 K with an interval of 5 K. The standard molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined, Δ c H m 0 (C5H12O5, cr) = (−2463.2 ± 1.2) kJ mol−1and Δ f H m 0 (C5H12O5, cr) = (−1219.3 ± 0.3) kJ mol−1, by means of a precision oxygen bomb combustion calorimeter at T = 298.15 K. DSC and TG measurements were performed to study the thermal stability of the compound. The results were in agreement with those obtained from heat capacity measurements.

The thermal stability and the kinetics of thermal decomposition of protionamide were studied by thermogravimetry. activation energy e-a of thermal decomposition of this substance was obtained to be 54.65 kj center dot mol(-1) by kissinger method and ozawa-flynn-wall method. kinetics model function and frequency factor a of protionamide were predicted with the malek method, which were f(alpha)=alpha(0.391)(1-alpha)(0.145) and ina=13.12, respectively. moreover, melting point, molar enthalpy and entropy of fusion of this compound were determined to be 414.09 k, 23.21 kj center dot mol(-1), and 56.06 j center dot mol(-1) center dot k-1, respectively.

An isoperibol solution−reaction calorimeter suitable for measuring molar enthalpies of solid−liquid and liquid−liquid interactions was constructed. The volume of calorimetric vessel made by transparent hard glass is about 100 cm3. Its energy equivalent is 0.48 kJ·K-1 when containing 100 cm3 of double distilled water. The thermal leakage modulus is 2.7 × 10-4 s-1. The time constant of the calorimeter is about 2.9 s. The precision of controlling and measuring the temperature is within ±0.001 K and ±0.0001 K, respectively. The performance of the calorimeter was tested by measuring the enthalpy of dissolution of KCl in double distilled water, Δs = (17 547 ± 13 J·mol-1) at T = (298.15 ± 0.001) K, and the measuring uncertainty was estimated to be within ±0.30% by comparing our measured value with the reference. Molar enthalpies of dissolution of the {ZnCl2(s) + l-His(s)} mixture and the complex Zn(His)Cl2·1/2H2O(s) in 100 cm3 of 2 mol·L-1 HCl at T = (298.15 ± 0.001) K have been measured to be Δd = (26.419 ± 0.0...

Heat capacities of 2,4-dichlorobenzaldehyde have been measured with a high-precision automatic adiabatic calorimeter over the temperature range from (79 to 371) K. The melting temperature, molar enthalpy, and entropy of fusion were determined by the heat capacity measurements to be (347.24 ± 0.13) K, (20468 ± 19) J · mol−1, and (58.94 ± 0.04) J · K−1 · mol−1, respectively. The melting temperatures for the sample and the absolutely pure compound have been obtained from fractional melting experiments to be (347.230 and 347.619) K, respectively, and the chemical purity of the sample was calculated to be 0.9921 mol fraction according to the Van't Hoff equation. Moreover, the solid-to-liquid phase transition of the substance was further investigated by using DSC technique. The results obtained from the heat capacity measurements were in agreement with those from the DSC analysis.

As one primary component of Vitamin B3, nicotinic acid [pyridine 3-carboxylic acid] was synthesized, and calorimetric study and thermal analysis for this compound were performed. The low-temperature heat capacity of nicotinic acid was measured with a precise automated adiabatic calorimeter over the temperature rang from 79 to 368 K. No thermal anomaly or phase transition was observed in this temperature range. A solid-to-solid transition at T trs=451.4 K, a solid-to-liquid transition at T fus=509.1 K and a thermal decomposition at T d=538.8 K were found through the DSC and TG-DTG techniques. The molar enthalpies of these transitions were determined to be Δtrs H m=0.81 kJ mol-1, Δfus H m=27.57 kJ mol-1 and Δd H m=62.38 kJ mol-1, respectively, by the integrals of the peak areas of the DSC curves.