The heat capacities of N-(tert-butoxycarbonyl)-l-phenylalanine (abbreviated to NTBLP in this article), as an important chemical intermediates used to synthesize proteins and polypeptides, were measured by means of a fully automated adiabatic calorimeter over the temperature range from 78 to 350 K. The measured experimental heat capacities were fitted to a polynomial equation as a function of temperature. The thermodynamic functions, HT − H298.15K and ST − S298.15K, were calculated based on the heat capacity polynomial equation in the temperature range of (80–350 K) with an interval of 5 K. The thermal stability of the compound was further studied using TG and DSC analyses; a possible mechanism for thermal decomposition of the compound was suggested.
A complex of neodymium perchloric acid coordinated with L-glutamic acid and imidazole, [Nd(Glu)(H2O)5(Im)3](ClO4)6·2H2O was synthesized and characterized by IR and elements analysis for the first time. The thermodynamic properties of the complex
were studied with an automatic adiabatic calorimeter and differential scanning calorimetry (DSC). Glass transition and phase
transition were discovered at 221.83 and 245.45 K, respectively. The glass transition was interpreted as a freezing-in phenomenon
of the reorientational motion of ClO4− ions and the phase transition was attributed to the orientational order/disorder process of ClO4− ions. The heat capacities of the complex were measured with the automatic adiabatic calorimeter and the thermodynamic functions
[HT-H298.15] and [ST-S298.15] were derived in the temperature range from 80 to 390 K with temperature interval of 5 K. Thermal decomposition behavior
of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scanning calorimetry
The paper describes a new transient hot wire instrument which employs 25.4 μm diameter tantalum wire with an insulating tantalum
pentoxide coating. This hot-wire cell with a thin insulating layer is suitable for measurement of the thermal conductivity
and the thermal diffusivity of electrically conducting and polar liquids. This instrument has been used for experimental measurement
of the thermal conductivity and the thermal diffusivity of poly(acrylic acid) solution (50 mass%) in the temperature range
of 299 to 368 K at atmospheric pressure. The thermal conductivity data is estimated to be accurate within ±4%. Thermal diffusivity
measurements have a much higher uncertainty (±30%) and need further refinement.
Polyaniline/α-Al2O3 (PANI/α-Al2O3) composites were synthesized by in situ polymerization through ammonium persulfate ((NH4)2S2O8, APS) oxidized aniline using HCl as dopant. XRD and FTIR were used to characterize the PANI/α-Al2O3 composites. The thermal stabilities and glass transition temperature (Tg) of PANI/α-Al2O3 composites were tested using thermogravimetric (TG) method and modulated differential scanning calorimetry (MDSC) technique.
The results of TG showed that the thermal stability of PANI/α-Al2O3 composite increased and then decreased with the increase in α-Al2O3 content. The derivative thermogravimetry (DTG) curves showed one step degradation of PANI when the α-Al2O3 content was lower than 52.5 mass%, and exhibited two steps degradation when the α-Al2O3 content was higher than 63.6 mass%. The MDSC curves showed that the Tg of PANI/α-Al2O3 composites increased and then decreased with the augment of α-Al2O3 for the interaction between PANI chains and the surface of α-Al2O3.
Barium benzoate was synthesized in a hydrothermal reaction. The complex was characterized by elemental analysis, IR spectroscopy and X-ray powder diffraction. It was monoclinic and had a layered structure. The mechanism of thermal decomposition of the barium benzoate was studied by using TG, DTA, IR and gas chromatography-mass spectrometry. In a nitrogen atmosphere, the barium benzoate decomposed to form BaCO3 and organic compounds: mainly benzophenone, triphenylmethane, etc.
Authors:F. Tian, L. Sun, J. Venart, R. Prasad, and S. Mojumdar
Various techniques and methodologies of thermal conductivity measurement have been based on the determination of the rate
of directional heat flow through a material having a unit temperature differential between its opposing faces. The constancy
of the rate depends on the material density, its thermal resistance and the heat flow path itself. The last of these variables
contributes most significantly to the true value of steady-state axial and radial heat dissipation depending on the magnitude
of transient thermal diffusivity along these directions. The transient hot-wire technique is broadly used for absolute measurements
of the thermal conductivity of fluids. Refinement of this method has resulted in a capability for accurate and simultaneous
measurement of both thermal conductivity and thermal diffusivity together with the determination of the specific heat. However,
these measurements, especially those for the thermal diffusivity, may be significantly influenced by fluid radiation. Recently
developed corrections have been used to examine this assumption and rectify the influence of even weak fluid radiation. A
thermal conductivity cell for measurement of the thermal properties of electrically conducting fluids has been developed and
Synthesis, characterization and thermal analysis of polyaniline (PANI)/ZrO2 composite and PANI was reported in our early work. In this present, the kinetic analysis of decomposition process for these
two materials was performed under non-isothermal conditions. The activation energies were calculated through Friedman and
Ozawa-Flynn-Wall methods, and the possible kinetic model functions have been estimated through the multiple linear regression
method. The results show that the kinetic models for the decomposition process of PANI/ZrO2 composite and PANI are all D3, and the corresponding function is ƒ(α)=1.5(1−α)2/3[1−(1-α)1/3]−1. The correlated kinetic parameters are Ea=112.7±9.2 kJ mol−1, lnA=13.9 and Ea=81.8±5.6 kJ mol−1, lnA=8.8 for PANI/ZrO2 composite and PANI, respectively.
The molar heat capacity Cp,m of 1,2-cyclohexane dicarboxylic anhydride was measured in the temperature range from T=80 to 390 K with a small sample automated adiabatic calorimeter. The melting point Tm, the molar enthalpy ΔfusHm and the entropy ΔfusSm of fusion for the compound were determined to be 303.80 K, 14.71 kJ mol−1 and 48.43 J K−1 mol−1, respectively. The thermodynamic functions [HT-H273.15] and [ST-S273.15] were derived in the temperature range from T=80 to 385 K with temperature interval of 5 K. The thermal stability of the compound was investigated by differential scanning
calorimeter (DSC) and thermogravimetry (TG), when the process of the mass-loss was due to the evaporation, instead of its
Conducting polyaniline/Cobaltosic oxide (PANI/Co3O4) composites were synthesized for the first time, by in situ deposition technique in the presence of hydrochloric acid (HCl)
as a dopant by adding the fine grade powder (an average particle size of approximately 80 nm) of Co3O4 into the polymerization reaction mixture of aniline. The composites obtained were characterized by infrared spectra (IR)
and X-ray diffraction (XRD). The composition and the thermal stability of the composites were investigated by TG-DTG. The
results suggest that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the
thermal stability for the composites is attributed to the interaction between PANI and nano-Co3O4.
Authors:X. Liu, H. Zhang, Z. Tan, K. Han, and L. Sun
The isoquinoline alkaloids were isolated from traditional Chinese drugs of Phellodendri Cortex, Radix Stephaniae Tetrandrae,
Corydalis Yanhusuo and Corydalis Bungeana. The power-time curves of growth of E. coli at different concentrations of isoquinoline alkaloid at 37�C were determined by a 2277 Thermal Activity Monitor. The rate
constant of bacteriostastic activity was calculated. The relationship between growth rate constant and concentration was established.
The optimum bacteriostastic concentration was determined. Experimental results have indicated that all the isoquinoline alkaloids
isolated from the four kinds of traditional Chinese drugs have bacteriostastic activity and the order is Phellodendri Cortex>Radix
Stephaniae Tetrandrae>Corydalis Yanhusuo>Corydalis Bungeana.