过氧化苯甲酰的热分解研究

The thermal decomposition process of benzoyl peroxide was investigated by Accelerating Rate Calorimeter. The curves of thermal decomposition temperature and pressure versus time for the systems were obtained. The curves of temperature rising-rate versus thermal decomposition temperature were also obtained. After the data revision disposal and analysis processing, thermal decomposition parameters and kinetic data of benzoyl peroxide were calculated, respectively.     

ASTM Kinetics of Oil Shales

Thermal analysis is increasingly being used to obtain kinetic data relating to sample decomposition. In this research differential scanning calorimeter (DSC) was used to determine the combustion kinetics of three (Çan, Himmetoglu and Mengen) oil shale samples by ASTM and Roger &; Morris methods. On DSC curves two reaction regions were observed on oil shale sample studied except Çan oil shale. In DSC experiments higher heating rates resulted in higher reaction temperatures and higher heat of reactions. Distinguishing peaks shifted to higher temperatures with an increase in heating rate. Three different kinetic models (ASTM I-II and Rogers &; Morris) were used to determine the kinetic parameters of the oil shale samples studied. Activation energies were in the range of 131.8-185.3 kJ mol-1 for ASTM methods and 18.5-48.8 kJ mol-1 for Rogers &; Morris method.     

气体流动热量计和苯、苯-环已烷气体热容的测量

A set of vapor-flow calorimeter has been constructed on the basis of Power's adiabatic calorimeter and Clarke s flash boiler. It can determine the heat capacities of mono-or multi-component vapors from vaporizing temperature to 600 K and 10—600 kPa pressures. For the calibration of the instrument, the heat capacities of benzene have been measured under 51.1, 101.3, 309.3 and 495.2 kPa and 370—600 K tempera-tures. For multicomponent vapor, benzene-cyclohexane has been determined. The results showed that the calorimeter has both the precision and accuracy better than 1.0% for either pure or mixtural vapors.     

A simple adiabatic low-temperature calorimeter based on a helium refrigerator system

The construction of an adiabatic calorimeter for the 15-300 K range is described. It is fully automated and set up in a helium refrigerator system. The operation of the calorimeter was tested by measuring the specific heat capacity of a pure copper sample. The results show good agreement with the standard literature values. The specific heat capacity of a magnesium hydride sample was also determined. For MgH₂, the standard molar entropy of S⁰(298.15)=30.64 J mol⁻¹ K⁻¹ was calculated from the obtained data.     

Changes in the Transfer Function of a flow microcalorimeter

Flow microcalorimeters are used to determine thermodynamic properties of liquid mixtures, the accuracy of these measures depends on the right calibration of the instrument. In this work the system is identified by means of the transfer functions of the two poles, it is proven that the first time constant and the sensitivity change with the value of rc _p f of the injected liquids (r - density, c _p - heat capacity, f - injection flow), and that the sensitivities obtained in the electrical and chemical calibrations are different for the same value of rc _p f because the dissipation in each case does not occur in the same place. As a summary of the calibration carried out, it is proposed a sensitivity value of 313±4 mV W^-1 for rc _p f<15 mW K^-1 that permits to make thermal measures with an uncertainty of 3%. This revised version was published online in July 2006 with corrections to the Cover Date.     

LOW-TEMPERATURE HEAT CAPACITIES AND THERMODYNAMIC PROPERTIES OF LANTHANUM AND CERIUM TRIISOTHIOCYANATE HYDRATESI (Ⅰ)——La(NCS)_3, 7H_2O AND Ce(NCS)_3. 7H_2O

The heat capacities of La(NCS)_3. 7H_2O and Ce(NCS)_3. 7H_2O have been measured from 13 to 300K with a fully-automated adiabatic calorimeter. The construction and procedures of the calorimetric system are described in detail. No obvious thermal anomaly was observed for both compounds in the experimental temperature range. The polynomial equations for calculating the heat capacity values of the two compounds in the range 13—300K were obtained by the least-squares fitting based on the experimental C_p data. The C_p values below 13K were estimated by using the Debye and Einstein heat Capacity functions. The standard molar thermodynamic functions were calculated from 0 to 300K. Gibbs energies of formation were also calculated.     

Synthesis of a series of triple-bridged cyclotriphosphazene hexa-alkoxy derivatives and investigation of their structural and mesomorphic properties

Triple diamino-bridged cyclotriphosphazene (1) was reacted in a 1:8 stoichiometry with the sodium derivatives of long-chain diols [1-octanol, 1-decanol, 1-dodecanol, 1-hexadecanol] tetrahydrofuran (THF) at room temperature to form hexa-substituted cyclotriphosphazene derivatives (2, 3, 4 and 5, respectively), whose mesomorphic behaviours were investigated for their possible applications as liquid crystals. The cylindrical-type cyclotriphosphazene derivatives (2–5) were characterised by mass and elemental analyses and by Fourier transform infrared spectroscopy (FT-IR), ¹H and ³¹P {¹H} NMR spectroscopies. The thermal and mesomorphic properties were investigated by differential scanning calorimetry and by polarising optical microscopy, respectively. It was found that liquid crystal materials could be obtained from compounds 3 and 4 with alkoxy chains rather than using aromatic ring(s) as mesogens as published previously.     

差示扫描量热仪检定用标准物质的研制

介绍了四种差示扫描量热仪温度标准物质的研制过程及所取得的研究成果。     

Thermodynamic study of the n-octane-1-pentanol-sodium dodecyl sulfate solutions in water

The thermodynamic properties, PVTx (T_S, P_S, ρ_S), (∂P/∂T)_VX, and C_VVTx, of three microemulsions (water + n-octane + sodium dodecylsulfate + 1-pentanol) with composition of solution-1: 0.0777 (H₂O):0.6997 (n-C₈H₁₈):0.0777 (SDS):0.1449 (1-C₅H₁₁OH) mass fraction; solution-2: 0.6220 (H₂O):0.1555 (n-C₈H₁₈):0.0777 (SDS):0.1448 (1-C₅H₁₁OH) mass fraction; and solution-3: 0.2720 (H₂O):0.5054 (n-C₈H₁₈):0.0777 (SDS):0.1449 (1-C₅H₁₁OH) mass fraction were measured. Sodium dodecylsulfate (SDS) was used as an ionic surfactant, 1-pentanol used as stabilizer (cosurfactant), and n-octane as oil component in aqueous solution. A high-temperature, high-pressure, adiabatic, and nearly constant-volume calorimeter supplemented by quasi-static thermogram technique was used for the measurements. Measurements were made at eight densities (isochores) between 475.87 and 919.03 kg m⁻³. The range of temperature was from 275 to 536 K and pressure range was up to 138 bar. Uncertainty of the pressure, density, derivative (∂P/∂T)_VX, and heat capacity measurements are estimated to be 0.25%, 0.02%, 0.12-1.5%, and 2.5%, respectively. Temperatures at liquid-gas phase transition curve, T_S(ρ), for each measured densities (isochores) were determined using a quasi-static thermogram technique. The uncertainty of the phase transition temperature measurements is about ±0.02 K. The effect of temperature, density, and concentration on the heat capacity of the microemulsions is discussed. Along the isochore of 438.40 kg m⁻³ at temperatures above 525.44 K for the first solution the precipitation of the solid phase (SDS) was found.     

Enthalpies of combustion and formation of 3-formylchromones

The enthalpies of combustion of 3-formylchromone (3F), 3-formyl-6-methylchromone (3F6M) and 3-formyl-6-isopropylchromone (3F6I) were determined by combustion calorimetry. The molar combustion energies () of the 3F, 3F6M and 3F6I are: −(4452.4 ± 1.8), −(5115.6 ± 2.7) and −(6411.4 ± 2.5) kJ mol⁻¹, respectively. The formation enthalpies in the crystalline state () are: −(340.2 ± 2.2), −(355.1 ± 3.1) and −(415.5 ± 3.0) kJ mol⁻¹, respectively.s