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991.
Agata Górska Karolina Szulc Ewa Ostrowska-Ligęza Joanna Bryś Magdalena Wirkowska-Wojdyła 《Journal of Thermal Analysis and Calorimetry》2017,128(1):177-183
Epoxy-based nanocomposites containing different concentrations (0–3%) of surface-modified graphene nanosheets (GNS) with 3-aminopropyltriethoxysilane were prepared and their thermal and mechanical properties including dynamic mechanical analysis, tensile strength, hardness, and abrasion tests were evaluated in order to have a database for thermo-mechanical properties of epoxy nanocomposites. The main aim of this study was to understand the optimum percentage of GNS which would perform the best reinforcing influence on mechanical and physical performance of an epoxy nanocomposite. The results explain how applying the analysis of variance (ANOVA) method as a useful tool in optimization of GNS concentration in preparation of high-performance epoxy-based nanocomposites. 相似文献
992.
Sanjay Kumar Ankur Jain Yoshitsugu Kojima 《Journal of Thermal Analysis and Calorimetry》2017,128(2):721-733
This paper studies the addition (0–40% w/w) of natural zeolite (NZ, 84% clinoptilolite) in blended cements made with Portland cement (PC) with low and medium C3A content. The isothermal calorimetry was used to understand the effect of NZ on the early cement hydration. For low C3A cement, the addition of NZ produces mainly a dilution effect and then the heat released curve is similar to plain cement with lower intensity. For medium C3A cement, the curve shows the C3S peak in advance and a high intensity of third peak attributed to C3A hydration. The high cation fixed of NZ reduces the ions concentration (especially alkalis) in the mixing water stimulating the PC hydration. The flowability decreases when the NZ replacement level increases. Results of Fratini’s test show that NZ with both PCs used presents slow pozzolanic activity. At early age, XRD and FTIR analyses confirm that hydration products are the same as that of the corresponding PC and the CH is progressively reduced after 28 days and some AFm phases (hemi- and monocarboaluminate) appear depending on the NZ percentage and the PC used. For low replacement levels, the compressive strength is higher than the corresponding PC from 2 to 28 days. For high replacement levels, the early compressive strength is lower than that of corresponding plain PC and the pozzolanic reaction improves the later compressive strength of blended cements. 相似文献
993.
Jianbing Hua Chao Wu Liming Zou Shuyun Chen Hongwei Lu Yongjing Xu Xianyang Peng 《Journal of Thermal Analysis and Calorimetry》2017,128(3):1273-1278
In this study, a series of binary mixtures of N-butyl stearate (nBS) and methyl palmitate (MP) were used to produce a novel composite phase change material (CPCM) for potential application in the eastern China, and their thermal properties were investigated by differential scanning calorimetry (DSC). The results of DSC indicated that the mixture consisting of 10 mass% nBS and 90 mass% MP is optimum as the CPCM in terms of the phase change temperature ranges (T f = 19.74–5.59 °C; T m = 18.34–33.80 °C) and latent heats (ΔH f = 176.8 J g?1; ΔH m = 189.3 J g?1). On the other hand, the thermal reliability and chemical stability of the CPCM after 120, 180, 240, 300, 360 and 500 accelerated thermal cycling tests were studied by DSC and fourier transform infrared (FTIR) analysis. The results demonstrated that the CPCM had good thermal reliability and chemical stability. 相似文献
994.
Sai-Bo Yu Ju-Lan Zeng Sai-Ling Sun Lei Zhou Yu-Hang Chen Liu-Bin Song Zhong Cao Li-Xian Sun 《Journal of Thermal Analysis and Calorimetry》2017,129(1):189-199
Solar absorption cooling is a wonderful method to provide cold energy by exploiting solar energy. Phase change materials (PCMs) that store latent thermal energy are indispensible in solar absorption cooling system. It is worthwhile to find new PCMs due to the demanding on the temperature of the stored thermal energy which in turn would power the absorption chiller. In this paper, two compounds: 1-bromo-2-methoxynaphthalene (compound 1) and 2,2′-diphenyl-4,4′-bi(1,3-dioxane)-5,5′-diol (compound 2), were selected as potential PCMs. Their thermal energy storage properties and thermal stability were characterized by differential scanning calorimetry and thermogravimetric analysis. The results showed that both compounds could be applied as good PCMs in solar absorption cooling systems. Compound 1 melted at 356.82 K with the ΔH of 98.81 J g?1, while compound 2 melted in a broad temperature range with the melting point of 466.26 K and the ΔH of 101.4 J g?1. Both compounds exhibited good thermal stability. Furthermore, the molar specific heat capacities of these two compounds were measured by temperature-modulated differential scanning calorimetry from 198.15 K to the temperature that they started to decompose, and the thermodynamic functions of [H T–H 298.15] and [S T–S 298.15] were calculated based on the specific heat capacities data. 相似文献
995.
Magdalena Leśniak Marcin Gajek Janusz Partyka Maciej Sitarz 《Journal of Thermal Analysis and Calorimetry》2017,130(1):165-176
In this work, the structure and thermal properties of aluminosilicate fritted glazes in SiO2–Al2O3–CaO–MgO–Na2O–K2O–ZnO system with (4.0 mol%) and without addition of ZnO were examined by GIXRD, FTIR, MAS-NMR and thermal methods (DTA, DIL). It has been found that the all experimental glazes are amorphous material (transparent glazes). On the base of spectroscopic investigations, it was found that zinc ions exist in the network glazes in the octahedral coordination—Zn2+ ions play a network modifier role in structure of glazes. An analysis of the data obtained from thermal tests showed that addition of ZnO into chemical composition results in decrease in glass transition temperature value (T g) for all glazes (DTA, DIL). The coefficient of thermal expansion (α) is decreased as the whole measurement range for one series of fritted glazes. 相似文献
996.
997.
Thermal and mechanical properties of chitosan nanocomposites with cellulose modified in ionic liquids 总被引:1,自引:0,他引:1
Aleksandra Grząbka-Zasadzińska Tazdin Amietszajew Sławomir Borysiak 《Journal of Thermal Analysis and Calorimetry》2017,130(1):143-154
In this paper, ionic liquid treatment was applied to produce nanometric cellulose particles of two polymorphic forms. A complex characterization of nanofillers including wide-angle X-ray scattering, Fourier transform infrared spectroscopy, and particle size determination was performed. The evaluated ionic liquid treatment was effective in terms of nanocrystalline cellulose production, leaving chemical and supermolecular structure of the materials intact. However, nanocrystalline cellulose II was found to be more prone to ionic liquid hydrolysis leading to formation larger amount of small particles. Each nanocrystalline cellulose was subsequently mixed with a solution of chitosan, so that composite films containing 1, 3, and 5% mass/mass of nanometric filler were obtained. Reference samples of chitosan and chitosan with micrometric celluloses were also solvent casted. Thermal, mechanical, and morphological properties of films were tested and correlated with properties of filler used. The results of both, tensile tests and thermogravimetric analysis showed a significant discrepancy between composites filled with nanocrystalline cellulose I and nanocrystalline cellulose II. 相似文献
998.
Anna Michnik Ewa Sadowska-Krępa Przemysław Domaszewski Klaudia Duch Ilona Pokora 《Journal of Thermal Analysis and Calorimetry》2017,130(3):1253-1262
Differential scanning calorimetry (DSC) has been used for the detection of post-exercise changes in blood serum resulting from participation in the CrossFit (CF) training combined with green tea extract (GTE) supplementation. Blood samples from 20 well-trained men were collected at rest, immediately post-exercise and after 1 h of recovery in two trials: first before and second after CF training combined with GTE or placebo administration in the supplemented (S) and control (C) groups, respectively. Selected muscle damage biomarkers have been compared in different phases of the experiment. A significant increase in blood lactate content has been observed post-exercise in both trials in both participants’ groups. The opposite trends have been noted for the C and S groups in creatine kinase (CK) activity changes recorded during the first to the second trial: an increase in CK for the control and a decrease for the supplemented group in all phases of the experiment: pre-exercise, post-exercise and after recovery. In the second trial, all CK values for the S group have been found significantly lower than the corresponding values recorded in the C group. These results suggest a mitigate effect of GTE supplementation on post-training muscle damage. DSC results did not reveal clear effects of training nor GTE supplementation on serum denaturation transition. However, interesting dependences of thermodynamic parameters describing this transition have been observed in different phases of the experiment. Statistically significant negative correlations have been found between post-training VO2max and post-exercise thermodynamic parameters associated with haptoglobin contribution to serum denaturation transition. 相似文献
999.
Sylwia Basąg František Kovanda Zofia Piwowarska Andrzej Kowalczyk Katarzyna Pamin Lucjan Chmielarz 《Journal of Thermal Analysis and Calorimetry》2017,129(3):1301-1311
The Co–Mg–Al mixed metal oxides were prepared by calcination of co-precipitated hydrotalcite-like precursors at various temperatures (600–800 °C), characterised with respect to chemical (AAS) and phase (XRD) composition, textural parameters (BET), form and aggregation of cobalt species (UV–vis-DRS) and their redox properties (H2-TPR, cyclic voltammetry). Moreover, the process of thermal decomposition of hydrotalcite-like materials to mixed metal oxide systems was studied by thermogravimetric method combined with the analysis of gaseous decomposition products by mass spectrometry. Calcined hydrotalcite-like materials were tested as catalysts for methanol incineration. Catalytic performance of the oxides depended on cobalt content, Mg/Al ratio and calcination temperature. The catalysts with lower cobalt content, higher Mg/Al ratio and calcined at lower temperatures (600 or 700 °C) were less effective in the process of methanol incineration. In a series of the studied catalysts, the best results, with respect to high catalytic activity and selectivity to CO2, were obtained for the mixed oxide with Co:Mg:Al molar ratio of 10:57:33 calcined at 800 °C. High activity of this catalyst was likely connected with the presence of a Co–Mg–Al spinel-type phases, containing easy reducible Co3+ cations, formed during high-temperature treatment of the hydrotalcite-like precursor. 相似文献
1000.
Istvan Hargittai 《Structural chemistry》2017,28(2):259-277
The Hungarian-born American chemistry Nobel laureate George A. Olah used superacids to give longer life to carbocations. He resolved a long-standing debate on reaction mechanism in organic chemistry and, more importantly, opened new vistas in hydrocarbon chemistry to produce hosts of new compounds. The concerted utilization of organic synthesis, physical techniques, and computational methods led to spectacular achievements in hydrocarbon chemistry. Olah has always been on the lookout for the practical applications of his discoveries in fundamental chemistry. He continued his research after his Nobel award and has worked out the idea, which he labeled “the methanol economy.” Olah’s example shows that a great researcher can also be a devoted and caring human being. 相似文献