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Abstract

The hydration heat of pure cement, fly ash single-doped cement, as well as fly ash and fluorgypsum co-doped cement were investigated by means of micro-calorimetry with an eight-channel micro-calorimeter. The results showed that the hydration heat and the hydration rate could be reduced significantly by fly ash and fluorgypsum. However, the reduction was not proportional to the loading of dopant. The exothermic peak of the co-doped cement was appeared earlier than that of the single-doped cement. As the temperature decreased, the hydration heat and the hydration rate of both the doped cement were reduced, and the exothermic peak appeared later. The effect of fly ash and fluorgypsum on the compressive strength of cement was also investigated. The results revealed that the early compressive strength of concrete made up of the co-doped cement was largely higher than that of the single-doped cement. Based on the experiment results obtained in this article, we could conclude that fluorgypsum is a suitable additive for the single-doped cement.

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Abstract

A three-dimensional lithium-based metal–organic framework Li2(2,6-NDC) (2,6-NDC = 2,6-naphthalene dicarboxylate) has been synthesized solvothermally and characterized by X-ray powder diffraction, elemental analysis, FT-IR spectroscopy, thermogravimetry and mass spectrometer analysis (TG–MS). The framework has exceptional stability and is stable to 863 K. The thermal decomposition characteristic of this compound was investigated through the TG–MS from 293 to 1250 K. The molar heat capacity of the compound was measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 195 to 670 K for the first time. The thermodynamic parameters such as entropy and enthalpy versus 298.15 K based on the above molar heat capacity were calculated.

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Abstract

Two metal-organic frameworks, Ca(2,6-NDC)(DMF) (1) and Mn3(2,6-NDC)3(DMF)4 (2) (where 2,6-NDC = 2,6-naphthalene dicarboxylate and DMF = N,N′-dimethylformamide) have been solvothermally synthesized under optimized conditions and characterized by X-ray powder diffraction, elemental analysis, FT-IR spectroscopy, and TG analysis. The thermal decomposition characteristics were investigated under air atmosphere from 300 to 1,170 K (for 1) and from 300 to 971 K (for 2). The molar heat capacities were measured from 198 to 548 K (for 1) and from 198 to 448 K (for 2) by temperature modulated differential scanning calorimetry (TMDSC) for the first time. The fundamental thermodynamic parameters such as entropy and enthalpy variations with temperature were calculated based on the experimentally determined molar heat capacities.

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Journal of Thermal Analysis and Calorimetry
Authors: Mei-Han Wang, Takayuki Konya, Masahiro Yahata, Yutaka Sawada, Akira Kishi, Takayuki Uchida, Hao Lei, Yoichi Hoshi, and Li-Xian Sun

Abstract  

A series of Alq3 thin films with the thicknesses of 50, 100, and 200 nm was deposited on Si substrates at room temperature using the thermal evaporation method. The thermal crystallization process of Alq3 thin films, especially 50 nm thick films, was successfully examined using high-temperature X-ray diffraction (HT-XRD) with the in-plane scan mode. Film thickness, density, and changes in surface roughness while heating were determined using X-ray reflectometry (XRR). The decreased density and increased surface roughness, which were accompanied by sublimation, indicate the instability of the Alq3 film. Thus, thermal instability is a major factor for device failure.

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Abstract

A new potential enantioselective catalyst derived from ferrocene, 1-{(R)-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethyl}-benzimidazole (DPFEB), was prepared and its absolute structure was characterized by means of single crystal X-ray diffraction. The molar heat capacity of DPFEB was measured by means of temperature modulated differential scanning calorimetry over the temperature range of 200–530 K, and the thermodynamic functions of [H TH 298.15] and [S TS 298.15] were calculated. Further more, thermogravimetry experiment revealed that DPFEB exhibited a three step thermal decomposition process with the final residual of 28.7%.

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Abstract  

The mechanism of solvent extraction of uranium(VI) from highly concentrated chloride solution with a quaternary ammonium salt, benzyloctadecyldimethylammonium chloride (BODMAC, R4NCl), dissolved in chloroform was studied. The compositions of the extracted species were R4N.UO2Cl3 and (R4N)2 .UO2Cl4. The extraction process is exothermic (ΔH° = -8.42±0.54 KJ/mol). Kex 1 and Kex 2 are calculated to be (3.62±0.55).10-2 and (1.06±0.17).103, respectively. In the extraction process, a W/O uranium(VI) rich emulsion solution has been formed between the organic and aqueous phases, its volume increased with the increase of BODMAC in the system. The influences of temperature, NaCl, MgCl2 and MgSO4 concentrations on the extraction equilibrium were also studied.

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Journal of Thermal Analysis and Calorimetry
Authors: Yi-Xi Zhou, Li-Xian Sun, Zhong Cao, Jian Zhang, Fen Xu, Li-Fang Song, Zi-Ming Zhao, and Yong-Jin Zou

Abstract

Two metal–organic frameworks (MOFs) of M(HBTC)(4,4′-bipy)·3DMF [M = Ni (for 1) and Co (for 2); H3BTC = 1,3,5-benzenetricarboxylic acid (1,3,5-BTC); 4,4′-bipy = 4,4′-bipyridine; DMF = N,N′-dimethylformamide] were synthesized by a one-pot solution reaction and a solvothermal method, respectively, and characterized by powder X-ray diffraction and FT-IR spectra. The low-temperature molar heat capacities of M(HBTC)(4,4′-bipy)·3DMF were measured by temperature-modulated differential scanning calorimetry (TMDSC) for the first time. The thermodynamic parameters 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 and the decomposition mechanism of M(HBTC)(4,4′-bipy)·3DMF were investigated by thermogravimetry analysis (TGA). The experimental results through TGA measurement demonstrate that both of the two compounds have a three-stage mass loss in air flow.

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Journal of Thermal Analysis and Calorimetry
Authors: Li-Fang Song, Chun-Hong Jiang, Jian Zhang, Li-Xian Sun, Fen Xu, Yun-Qi Tian, Wan-Sheng You, Zhong Cao, Ling Zhang, and Dao-Wu Yang

Abstract  

A novel two-dimensional metal organic framework MgBTC [MgBTC(OCN)2·2H2O, where BTC = 1,3,5-benzenetricarboxylate] has been synthesized solvothermally and characterized by single crystal XRD, powder XRD, FT-IR spectra. The low-temperature molar heat capacities of MgBTC were measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 190 to 350 K for the first time. No phase transition or thermal anomaly was observed in the experimental temperature range. The thermodynamic parameters of MgBTC such as entropy and enthalpy relative to reference temperature of 298.15 K were derived based on the above molar heat capacities data. Moreover, the thermal stability and decomposition of MgBTC was further investigated through thermogravimetry (TG)-mass spectrometer (MS). Four stages of mass loss were observed in the TG curve. TG-MS curve indicated that the products of oxidative degradation of MgBTC are H2O, N2, CO2 and CO. The powder XRD showed that the mixture after TG contains MgO and graphite.

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Journal of Thermal Analysis and Calorimetry
Authors: Chun-Hong Jiang, Li-Fang Song, Jian Zhang, Li-Xian Sun, Fen Xu, Fen Li, Qing-Zhu Jiao, Zhen-Gang Sun, Yong-Heng Xing, Yong Du, Ju-Lan Zeng, and Zhong Cao

Abstract

A novel metal organic framework [Co (BTC)1/3 (DMF) (HCOO)]n (CoMOF, BTC = 1,3,5-benzene tricarboxylate, DMF = N,N-dimethylformamide) has been synthesized solvothermally and characterized by single crystal X-ray diffraction, X-ray powder diffraction, and FT-IR spectra. The molar heat capacity of the compound was measured by modulated differential scanning calorimetry (MDSC) over the temperature range from 198 to 418 K for the first time. The thermodynamic parameters such as entropy and enthalpy versus 298.15 K based on the above molar heat capacity were calculated. Moreover, a four-step sequential thermal decomposition mechanism for the CoMOF was investigated through the thermogravimetry and mass spectrometer analysis (TG-DTG-MS) from 300 to 800 K. The apparent activation energy of the first decomposition step of the compound was calculated by the Kissinger method using experimental data of TG analysis.

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