Authors:H. Zhang, Z. Chai, H. Sun, J. Zhang, H. Ouyang, L. Xin, and Y. Chuai
The concentrations and distributions of total halogen (TX), extractable organohalogen (EOX) and extractable persistent organohalogen
(EPOX) were determined in 20 kinds of yogurt specimens collected from Chinese supermarkets using neutron activation analysis
(NAA) and gas chromatography equipped with a 63Ni electron capture detector (GC-ECD). The results indicated that the halogens in yogurt mainly existed as non-extractable
organohalogen compounds. About 25–30% of EOX was EPOX. EOCl and EPOCl were the main organohalogen species in yogurt. The average
concentration of the identified organochlorine, such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs),
was below 4% of EPOCl.
Authors:B. Liu, Z. Tan, Z. Nan, P. Liu, L. Sun, F. Xu, and X. Lan
A solid complex of rare-earth compounds with alanine, [ErY(Ala)4(H2O)8](ClO4)6 (Ala=alanine), was synthesized, and a calorimetric study and thermal analysis for it was performed through adiabatic calorimetry
and thermogravimetry. The low-temperature heat capacity of [ErY(Ala)4(H2O)8](ClO4)6 was measured with an automated adiabatic precision calorimeter over the temperature range from 78 to 377 K. A solid-solid
phase transition was found between 99 and 121 K with a peak temperature at 115.78 k. The enthalpy and entropy of the phase
transition was determined to be 1.957 Kj mol-1, 16.90 j mol-1 k-1, respectively. Thermal decomposition of the complex was investigated in the temperature range of 40~550C by use of the thermogravimetric
and differential thermogravimetric (TG/DTG) analysis techniques. The TG/DTG curves showed that the decomposition started from
120 and ended at 430C, completed in three steps. A possible mechanism of the thermal decomposition was elucidated.
Authors:S. Wang, Z. Tan, Y. Di, F. Xu, M. Wang, L. Sun, and T. Zhang
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 Ttrs=451.4 K, a solid-to-liquid transition at Tfus=509.1 K and a thermal decomposition at Td=538.8 K were found through the DSC and TG-DTG techniques. The molar enthalpies of these transitions were determined to be
ΔtrsHm=0.81 kJ mol-1, ΔfusHm=27.57 kJ mol-1 and ΔdHm=62.38 kJ mol-1, respectively, by the integrals of the peak areas of the DSC curves.
Authors:F. Xu, L. Sun, Z. Tan, X. Lan, P. Yu, and T. Zhang
The heat capacities of berberine sulphate [(C20H18NO4)2SO43H2O] were measured from 80 to 390 K by means of an automated adiabatic calorimeter. Smoothed heat capacities, HT-H298.15 and ST-S298.15 were calculated. The loss of crystalline water started at about 339.30.2 K, and its peak temperature was 365.80.6 K. The
peak temperature of decomposition for berberine sulphate was at about 391.40.4 K by DSC curve. TG-DTG analysis of this material
was carried out in temperature range from 310 to 970 K. TG and DSC curves show that there is no melting in the whole heating
Authors:Z. Zhang, L. Sun, Z. Tan, F. Xu, X. Lv, J. Zeng, and Y. Sawada
The molar heat capacities of the room temperature ionic liquid 1-butylpyridinium tetrafluoroborate (BPBF4) were measured by an adiabatic calorimeter in temperature range from 80 to 390 K. The dependence of the molar heat capacity
on temperature is given as a function of the reduced temperature X by polynomial equations, Cp,m [J K−1 mol−1]=181.43+51.297X −4.7816X2−1.9734X3+8.1048X4+11.108X5 [X=(T−135)/55] for the solid phase (80–190 K), Cp,m [J K−1 mol−1]= 349.96+25.106X+9.1320X2+19.368X3+2.23X4−8.8201X5 [X=(T−225)/27] for the glass state (198–252 K), and Cp,m[J K−1 mol−1]= 402.40+21.982X−3.0304X2+3.6514X3+3.4585X4 [X=(T−338)/52] for the liquid phase (286–390 K), respectively. According to the polynomial equations and thermodynamic relationship,
the values of thermodynamic function of the BPBF4 relative to 298.15 K were calculated in temperature range from 80 to 390 K with an interval of 5 K. The glass transition
of BPBF4 was observed at 194.09 K, the enthalpy and entropy of the glass transition were determined to be ΔHg=2.157 kJ mol−1 and ΔSg=11.12 J K−1 mol−1, respectively. The result showed that the melting point of the BPBF4 is 279.79 K, the enthalpy and entropy of phase transition were calculated to be ΔHm = 8.453 kJ mol−1 and ΔSm=30.21 J K−1 mol−1. Using oxygen-bomb combustion calorimeter, the molar enthalpy of combustion of BPBF4 was determined to be ΔcHm0 = −5451±3 kJ mol−1. The standard molar enthalpy of formation of BPBF4 was evaluated to be ΔfHm0 = −1356.3±0.8 kJ mol−1 at T=298.150±0.001 K.
Authors:J. Zhang, J. Zeng, Y. Liu, L. Sun, F. Xu, W. You, and Y. Sawada
Pb(1,4-BDC)·(DMF)(H2O) (1,4-BDC=1,4-benzenedicarboxylate; DMF=dimethylformamide) has been synthesized and investigated by elemental analysis,
FTIR spectroscopy, thermogravimetry (TG), derivative thermogravimetry (DTG). TG-DTG curves show that the thermal decomposition
occurs in four stages and the corresponding apparent activation energies were calculated with the Ozawa-Flynn-Wall (OFW) and
the Friedman methods. The most probable kinetic model function of the dehydration reaction of the compound has been estimated
by the Coats-Redfern integral and the Achar-Bridly-Sharp differential methods in this study.
Authors:Y. Qi, F. Xu, H. Ma, L. Sun, J. Zhang, and T. Jiang
Polyaniline/γ-Al2O3 (PANI/γ-Al2O3) composites were synthesized by in-situ polymerization at the presence of HCl as dopant by adding γ-Al2O3 nanoparticles into aniline solution. The composites were characterized by FTIR and XRD. The thermogravimetry (TG) and modulated
differential scanning calorimetry (MDSC) were used to study the thermal stability and glass transition temperature (Tg) of the composites, respectively.
The results of FTIR showed that γ-Al2O3 nanoparticles connected with the PANI chains and affected the absorption characteristics of the composite through the interaction
between PANI and nano-sized γ-Al2O3. And the results of XRD indicated that the peaks intensity of the PANI/γ-Al2O3 composite were weaker than that of the pure PANI. From TG and derivative thermogravimetry (DTG) curves, it was found that
the pure PANI and the PANI/γ-Al2O3 composites were all one step degradation. And the PANI/γ-Al2O3 composites were more thermal stable than the pure PANI. The MDSC curves showed that the nano-sized γ-Al2O3 heightened the glass transition temperature (Tg) of PANI.
Authors:J. Zeng, Y. Liu, Z. Cao, J. Zhang, Z. Zhang, L. Sun, and F. Xu
We prepared PANI/tetradecanol/MWNTs composites via in-situ polymerization. DSC results indicated that the composites are good
form-stable phase change materials (PCMs) with large phase change enthalpy of 115 J g−1. The MWNTs were randomly dispersed in the composites and significantly enhanced the thermal conductivity of the PCMs from
0.33 to 0.43 W m−1 K−1. The form-stable PCMs won’t liquefy even it is heated at 80°C, so that the MWNTs were fixed in the composite and the phase
separation of the MWNTs from PANI/tetradecanol/MWNTs composites won’t occur.
Authors:J. Zeng, J. Zhang, Y. Liu, Z. Cao, Z. Zhang, F. Xu, and L. Sun
Polyaniline (PANI)/1-tetradecanol (TD) composite materials, a kind of novel composite that can conduct electricity and store
thermal energy at the same time, thus possess the ability to endure certain heat shock, were prepared for the first time.
FTIR and XRD results showed that there were some interactions existed between PANI and TD. The thermal stability of the composites
exhibited both the characteristics of PANI and TD. The DSC experiments showed that the highest phase change enthalpy of the
composites could be as 73% as that of TD, indicating it was a good form-stable phase change material. The thermal conductivity
of the composites was also improved. The AC (Alternating Current) conductivity of the composites was enhanced to close to
that of PANI when the mass fraction of PANI in the composite was increased to 46%. Heat shock experiments showed that the
heat shock resistibility of the composite was greatly improved comparing to that of pure PANI.
Authors:S. Qiu, H. Chu, J. Zhang, Y. Qi, L. Sun, and F. Xu
The low-temperature molar heat capacities of CoPc and CoTMPP were measured by temperature modulated differential scanning
calorimetry (TMDSC) over the temperature range from 223 to 413 K for the first time. No phase transition or thermal anomaly
was observed in the experimental temperature range for CoPc. However, a structural change was found to be nonreversible for
CoTMPP in the temperature range of 368–403 K, which was further validated by the results of IR and XRD. The molar enthalpy
ΔHm and entropy ΔSm of phase transition of the CoTMPP were determined to be 3.301 kJ mol−1 and 8.596 J K−1 mol−1, respectively. The thermodynamic parameters of CoPc and CoTMPP such as entropy and enthalpy relative to reference temperature
298.15 K were derived based on the above molar heat capacity data. Moreover, the thermal stability of these two compounds
was further investigated through TG measurements. Three steps of mass loss were observed in the TG curve for CoPc and five
steps for CoTMPP.