Search

Thermal analysis is widely used for the measurement of the relationship between temperature and physical properties of the materials. Many studies have reported different thermal analysis methods, including thermogravimetry (TG), derivative thermogravimetry (DTG), differential heat analysis (DTA), and differential scanning calorimetry (DSC), but few comprehensively studied the factors influencing TG-DTA by the combined thermogravimetry–differential thermal methods. In this study, taking chalcanthite as the research object, the thermogravimetric–differential thermal analyses were systematically conducted by using synchronous thermal analyzer technology. The results demonstrate that 1) DTA curves of low- and medium-weight chalcanthite show five dehydration endothermic peaks, while TG curves do not display obvious weight-loss steps; DTA and TG curves of high-weight chalcanthite samples, on the other hand, illustrate three endothermic peaks, indicating three-step loss of crystalline water; 2) higher weight of samples may cause longer time of internal heat transfer and larger temperature gradient, consequently resulting in the expansion of DTA peak shape and the decline of resolution as well as the increase of the peak temperature; 3) the weight-loss deviation between the measured and theoretical data is relatively higher in the low-weight samples than that in the medium- and high-weight samples; 4) the heating rate can increase the DTA curve peak and thermal inertia and the temperature at the thermodynamic equilibrium, causing the temperature lagging behind and the overall peak moving toward high temperature; 5) sample grinding may destroy the structure of the crystal, thereby breaking the relatively weak chemical bond, and thus affects the structure of thermogravimetric–differential thermal analyses. These suggest that the sample weight, heating rate, and sample grinding probably have significant effects on the thermogravimetric–differential thermal analyses. Therefore, proper experimental conditions are needed to obtain the accurate results during the thermogravimetric–differential thermal analyses. This study can provide a basis and reference for future synchronous thermal analyses.

• The effects of nano-silica on early mechanical properties in winter construction were investigated. • The moderate nano-silica enhances the early hydration of alite, as indicated by the extra portlandite in early age. • Nano-silica promotion on C 3 A hydration is the main source of early properties improvement of cement. Fast hardening and high early strength are crucial factors for concrete used in tunnel construction in cold regions. The incorporation of nano-silicate has been found to be an effective method for improving the properties of cement-based materials at an early age. Thus, the objective of this paper is to investigate the nano-modification effects of different nano-silica contents on the hydration process, mechanical properties, and hydration products of cement cured in a low-temperature environment. The effects of various nano-silica concentrations, including 1%, 2%, 3%, and a high dose of 6%, on the properties of the concrete were investigated. According to the test results, the optimal quantity of nano-silica plays a crucial role in determining the properties of concrete. The effects of nano-silica on the hydration of C 3 A were found to dominate the cement hydration process at an early age. The incorporation of nano-silica led to a significant improvement in the dissolution rate of anhydrite and the reaction rate of the C 3 A renewal, which may be responsible for the gain in early strength of concrete. However, an excessive amount of nano-silica could negatively affect the hydration process of the alite and C 3 A, as evidenced by the total heat generated during the silica and aluminate reactions. The XRD patterns further confirmed these results. [ABSTRACT FROM AUTHOR]

The [Pd(dpa)(tsser)] complex ( 1) is prepared from the reaction of PdCl and 2,2′-dipyridylamine (dpa) with 4-toluenesulfonyl-L-serine (tsserH). This complex is characterized by spectral methods (IR, UV-Vis, H NMR, and luminescence), elemental analysis, thermal analysis (TG, DTA), and single crystal X-ray diffraction. X-ray structure determinations show that in this complex, Pd atoms are four-coordinated in a distorted square-planar configuration by two N atoms from a bidentate 2,2′-dipyridylamine ligand and one N atom and one O atom from a bidentate tsser ligand. [ABSTRACT FROM AUTHOR]

[Ba(5,5´-dcbipy)(μ-H2O)2(H2O)2]n(1) complex was obtained from the reaction of one equivalent of 2,2'-bipyridine-5,5'-dicarboxylic acid (5,5´-dcbipy.H2) and one equivalent of ethylene diamine (en) with one equivalent of BaCl2.2H2O in water. This complex was characterized by elemental analysis, IR, UV-Vis, and luminescence spectroscopy and its structure was studied by the single-crystal X-ray diffraction method. The thermal stability of1was studied by thermogravimetric and differential thermal analyses. [ABSTRACT FROM AUTHOR]

[In(4,4′-dtbu-2,2′-bipy)Cl3(DMSO)].2DMSO (1) complex was obtained from the reaction of 1 equivalent of InCl3.4H2O with 1 equivalent of 4,4′-di-tert-butyl-2,2′-bipyridine (4,4′-dtbu-2,2′-bipy) in a methanol solution. This compound was recrystallized in a DMSO/methanol solution to obtain suitable crystals for X-ray studies. This complex was characterized by elemental analysis, IR, UV-Vis,1H NMR,13C{1H} NMR, and luminescence spectroscopy and its structure was studied by the single-crystal diffraction method. The thermal stability of 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). [ABSTRACT FROM PUBLISHER]

For construction of roads and highways, a large amount of aggregate usage is needed. Because the natural aggregate resources are limited, the demand for the use of alternative aggregates has increased. For this reason, borogypsum in Turkey was used as a mineral filler aggregate in hot-mix asphalt concrete. When this is directly released to nature as boron waste, it may cause various environmental problems. In order to prevent this waste's harmful effects to the environment, the use of borogypsum as an alternative aggregate in highway engineering may be effective. For this purpose, the physical properties of borogypsum were investigated by thermogravimetry differential thermal analysis (TG-DTA), x-ray diffraction (XRD), and scanning electron microscope energy dispersion analysis of x-ray (SEM-EDAX). Also, the surface properties of borogypsum were identified by polarized optical microscope (POM). In this study, two groups of hot-mix asphalt concrete were obtained. For the first group, asphalt concrete was produced with limestone aggregate, and for the second one, borogypsum was used as mineral filler in asphalt concrete. In both groups, limestone was used as fine and coarse aggregate. Marshall stability and other mechanical properties were determined. It is believed that the evaluated borogypsum has a similar crystal structure with tincalconite and its usage for hot-mix climate regions may be effective to reduce problems. Also, another crucial finding is that using borogypsum as a mineral filler aggregate in asphalt concrete can be convenient for the binder course of pavements exposed to heavy traffic potential. [ABSTRACT FROM AUTHOR]

Fourier transform-infrared (FT-IR), Thermogravimetry (TG), Differential thermal analyses (DTA) and Differential Thermogravimetric (DTG) studies of a mixture of vegetable waste, saw dust, tree leaves and cow dung for microbial activity (feedstock) and their compost were reported in three different seasons i.e. winter, spring and summer. The correlation between spectral studies and compost composition provide information regarding their stability and maturity during composting. FT-IR spectra were conferred the functional groups and their intensity and TG, DTG and DTA for wt. loss, rate of wt. loss and enthalpy change in compost. Weight loss in feedstock and compost at two different temperatures 250-350 and 350-500°C was found 38.06, 28.15% for inlet and 14.08, 25.67% for outlet zones in summer and 50.59, 29.76% for inlet and 18.08, 25.67% in outlet zones in spring season, higher (5-10%) than winter. The corresponding temperatures in DTA in the samples from inlet to outlet zone were; endotherm (100-200°C), due to dehydration, exotherm (300-320°C), due to peptidic structure loss and exotherm (449-474°C) due to the loss of polynuclear aromatic structures, which were higher by 4°C and 10-20°C and rate of wt. loss was higher by 5-10% in spring and summer season, respectively than winter season composting, reported regardless of the maturation age of the compost. Relative intensity of exotherms (300-320/449-474°C) gave the thermally more stable fractions of organic compound. Our results indicated that the rotary drum composting of organic matters in spring and summer season gave higher molecular complexity and stability than the winter season. [ABSTRACT FROM AUTHOR]

Thermal analysis is widely used for the measurement of the relationship between temperature and physical properties of the materials. Many studies have reported different thermal analysis methods, including thermogravimetry (TG), derivative thermogravimetry (DTG), differential heat analysis (DTA), and differential scanning calorimetry (DSC), but few comprehensively studied the factors influencing TG-DTA by the combined thermogravimetry-differential thermal methods. In this study, taking chalcanthite as the research object, the thermogravimetric-differential thermal analyses were systematically conducted by using synchronous thermal analyzer technology. The results demonstrate that 1) DTA curves of low- and medium-weight chalcanthite show five dehydration endothermic peaks, while TG curves do not display obvious weight-loss steps; DTA and TG curves of high-weight chalcanthite samples, on the other hand, illustrate three endothermic peaks, indicating three-step loss of crystalline water; 2) higher weight of samples may cause longer time of internal heat transfer and larger temperature gradient, consequently resulting in the expansion of DTA peak shape and the decline of resolution as well as the increase of the peak temperature; 3) the weight-loss deviation between the measured and theoretical data is relatively higher in the low-weight samples than that in the medium- and high-weight samples; 4) the heating rate can increase the DTA curve peak and thermal inertia and the temperature at the thermodynamic equilibrium, causing the temperature lagging behind and the overall peak moving toward high temperature; 5) sample grinding may destroy the structure of the crystal, thereby breaking the relatively weak chemical bond, and thus affects the structure of thermogravimetric-differential thermal analyses. These suggest that the sample weight, heating rate, and sample grinding probably have significant effects on the thermogravimetric-differential thermal analyses. Therefore, proper experimental conditions are needed to obtain the accurate results during the thermogravimetric-differential thermal analyses. This study can provide a basis and reference for future synchronous thermal analyses., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Xianzhe, Nan, Yuyuan and Zhenping.)