Synthesis of composites and study of the thermal behavior of sugarcane bagasse/iron nitrate mixtures in different proportions

Two thermoanalytical techniques, differential thermal analysis (DTA) and thermogravimetry (TG), have always held the limelight. However, there has been an increasing trend to introduce variants of these for specific purposes, to develop methods dependent on properties other than energy and mass, to employ several techniques simultaneously and to combine thermoanalytical and non-thermoanalytical methods. The main aim of these developments is to produce in the minimum time the maximum amount of relevant and accurate information on the systems studied.Variants of DTA, obtained by altering specimen holder design, by changing furnace atmosphere, by modifying sample size or by dispensing with the reference material, can improve the accuracy of energy-change determination, permit measurement of various thermal constants and allow examination of materials that would not give interpretable results in conventional equipment. Variants of TG can be used to derive more accurate kinetic information. Differential scanning calorimetry (DSC) has a somewhat different basis from DTA and is fundamentally quantitative for energy changes; recent developments allow it to be used to about 750 °C, opening the possibility of its application to a much wider range of materials.Changes observed in dimensions and in mechanical, optical, electrical, magnetic and acoustic properties on heating all assist in interpreting the significance of results obtained by DTA, DSC and TG.Evolved gas detection and evolved gas analysis are gaining increasing recognition. Although usually coupled with DTA or TG measurements, they are sometimes used independently, as in thermal volatilisation analysis, which is of value in the study of polymers, and in rapid pyrolysis coupled with gas chromatography or mass spectrometry, which has yielded interesting information on the nature of organic materials.The use of two or more methods to examine one sample simultaneously has several advantages, particularly in facilitating comparison and interpretation of results. Although the optimum conditions for one determination are not necessarily those for another and care must therefore be taken in assessing results, multiple techniques can serve a useful function in many investigations.Future trends seem to be towards the increasing development of some currently less well established methods; more extensive application of computers in experimental control and in interpretation of results can also be expected. In certain applications, the links with calorimetry may well become closer.

Research for new anode materials has been stimulated by the development of lithium ion batteries since the introduction of carbon as a negative material in 1990 by Sony Energetics Inc. Some metal oxides and metalbased composite oxides [1, 2], nitrides [3, 4] and intermetallics [5, 6], which capacities are comparable or superior to those of graphitized carbon (theoretical maximum capacity of 372 mA hr g−1 [7, 8]), were considered as possible candidates for next generation of anode materials. Recently, several vanadium composite oxides exhibited their high-capacity and high-rate performance as negative electrode materials due to their open structure and interesting characteristics from a standpoint of the variety of oxidation states [9–12]. LiMoVO6 crystallizes with the ThTi2O6 branneritetype structure [13] and its electrochemical properties as a positive electrode material for lithium secondary batteries have been investigated [14–16]. But the performance of LiMoVO6 as negative electrode material was seldom reported. In this work, brannerite-type LiMoVO6 powder was obtained by rheological phase reaction method [17]. The result of electrochemical tests showed that the obtained LiMoVO6 as a novel anode material was also feasible and demonstrated very high energy density. The precursor was prepared by rheological phase reaction method. Analytical reagent grade chemicals, LiOH·H2O, NH4VO3 and (NH4)6Mo7O24·4H2O, were used as the starting materials and fully mixed by grinding in a 1:1:1 molar ratio. A proper amount of water was added to get a rheological body and the mixture was sealed in a closed container for 8 hr at 80 ◦C. After drying under vacuum at 80 ◦C for several hours, the precursor was pyrolyzed at 550 ◦C for 10 hr in air, and soft yellow powder LiMoVO6 was obtained. Thermogravimetry and differential thermal analysis (TG/DTA) of the precursor were performed by the Netzsch STA 449 thermal analysis system at a heating rate of 10 ◦C/min in air. The X-ray diffraction (XRD) measurements of the sample were carried out by Shimadzu XRD-6000 diffractometer with CuKα1 radiation (λ = 1.54056 A). The particle sizes and morphological features were observed by a scanning electron microscope (Hitachi SEM X-650).

Research for new anode materials has been stimulated by the development of lithium ion batteries since the introduction of carbon as a negative material in 1990 by Sony Energetics Inc. Some metal oxides and metalbased composite oxides [1, 2], nitrides [3, 4] and intermetallics [5, 6], which capacities are comparable or superior to those of graphitized carbon (theoretical maximum capacity of 372 mA hr g−1 [7, 8]), were considered as possible candidates for next generation of anode materials. Recently, several vanadium composite oxides exhibited their high-capacity and high-rate performance as negative electrode materials due to their open structure and interesting characteristics from a standpoint of the variety of oxidation states [9–12]. LiMoVO6 crystallizes with the ThTi2O6 branneritetype structure [13] and its electrochemical properties as a positive electrode material for lithium secondary batteries have been investigated [14–16]. But the performance of LiMoVO6 as negative electrode material was seldom reported. In this work, brannerite-type LiMoVO6 powder was obtained by rheological phase reaction method [17]. The result of electrochemical tests showed that the obtained LiMoVO6 as a novel anode material was also feasible and demonstrated very high energy density. The precursor was prepared by rheological phase reaction method. Analytical reagent grade chemicals, LiOH·H2O, NH4VO3 and (NH4)6Mo7O24·4H2O, were used as the starting materials and fully mixed by grinding in a 1:1:1 molar ratio. A proper amount of water was added to get a rheological body and the mixture was sealed in a closed container for 8 hr at 80 ◦C. After drying under vacuum at 80 ◦C for several hours, the precursor was pyrolyzed at 550 ◦C for 10 hr in air, and soft yellow powder LiMoVO6 was obtained. Thermogravimetry and differential thermal analysis (TG/DTA) of the precursor were performed by the Netzsch STA 449 thermal analysis system at a heating rate of 10 ◦C/min in air. The X-ray diffraction (XRD) measurements of the sample were carried out by Shimadzu XRD-6000 diffractometer with CuKα1 radiation (λ = 1.54056 A). The particle sizes and morphological features were observed by a scanning electron microscope (Hitachi SEM X-650).

Preparation of innovative eco-efficient composite bricks based on zeolite-poor rock and Hen's eggshell

A combination of analytical techniques such as atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), infra red spectral (IR) analysis, energy dispersive analysis of X-ray (EDAX), differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were employed to characterize clays from Odukpani, Cross River State, Nigeria. The samples were also subjected to physico-chemical tests. The results obtained show that the silicon content was the highest and that of manganese the lowest. The silica (SiO2) content was found to be 47.52% followed by alumina (Al2O3) 34.01%, iron oxide (Fe2O3) 2.38% and trace amounts of other elements such as Ca, Mg, Na and Mn (0.038, 0.188, 1.78 and 0.00%, respectively). The X-ray diffraction studies showed that the clay deposits consist predominantly of kaolinite and quartz with trace amounts of illites and biotite minerals. The infra red spectral analysis between 400 and 3700 cm-1 revealed interesting wave numbers and absorption bands. EDAX analysis of the clay samples reveals that Al and Si, were in the ratio of 1:2 whereas other elements like K, Ti and Fe were below detection limits. The thermal analysis revealed thermograms that provided valuable information on the purity of the starting materials and the mode of the reactions of the various clay samples. Key words: Odukpani clays, atomic absorption spectroscopy, infra-red spectral and energy dispersive analysis of X-ray, differential thermal and thermogravimetric analysis.

There are many thermoanalytical techniques but only several of them such as thermogravimetric analysis (TG), high resolution thermogravimetric analysis (Hi-Res™ TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA), calorimetry, differential scanning calorimetry (DSC), modulated differential scanning calorimetry (MDSC), evolved gas analysis (EGA), transient thermal analysis (TTA) and thermal conductivity (k) have selected to be discussed in this paper. Simultaneous thermal analysis (STA) is ideal for investigating issues such as the glass transition of modified glasses, binder burnout, dehydration of ceramic materials or decomposition behaviour of inorganic building materials, also with gas analysis. Selected applications of various thermoanalytical techniques from medicine to construction have also been discussed in this paper.

Dry scrubber residue from municipal solid waste incineration (MSWI) was characterized to identify critical inorganic pollutants and to suggest a conceptual treatment method. The key methods used were thermal analysis, including thermogravimetry (TG) and differential thermal analysis (DTA), pHstat titration, qualitative X-ray diffraction (XRD), scanning electron microscopy (SEM), chemical equilibrium calculations, and statistics such as error propagation, principal component analysis (PCA), and empirical modeling based on factorial designs. Based on EU directives, the major inorganic pollutants Cd, Cr, Pb, and Zn were found. In addition, the pH was too high. With dry scrubber residue stabilization in mind, the impact of carbonation and hydration was assessed and judged to be encouraging. In particular, chemical equilibrium calculations showed that carbonation has considerable potential to lower the pH and the availability of Pb, Zn, and Cr. The impact of carbonation on the mobility of Cd was found to be small. During carbonation, a metal-trapping calcium aluminosilicate hydrate (C–A–S–H) phase is also formed. Both processes together have the potential to lead to a robust, reliable, and reasonable stabilization method for dry scrubber residue. However, to control these processes, the decisive factors need to be identified and their effects need to be quantified. Ca, Cl, Na, and K might be abundant components which would be mobile even after stabilization.

Scholars are looking for solutions to substitute hazardous substances in manufacturing nanocellulose from bio-sources to preserve the world's growing environmental consciousness. During the past decade, there has been a notable increase in the use of cellulose nanocrystals (CNCs) in modern science and nanotechnology advancements because of their abundance, biocompatibility, biodegradability, renewability, and superior mechanical properties. Spherical cellulose nanocrystals (J-CNCs) were successfully synthesized from Jenfokie micro-cellulose (J-MC) via sulfuric acid hydrolysis in this study. The yield (up to 58.6%) and specific surface area (up to 99.64 m2/g) of J-CNCs were measured. A field emission gun-scanning electron microscope (FEG-SEM) was used to assess the morphology of the J-MC and J-CNC samples. The spherical shape nanoparticles with a mean nano-size of 34 nm for J-CNCs were characterized using a transmission electron microscope (TEM). X-ray diffraction (XRD) was used to determine the crystallinity index and crystallinity size of J-CNCs, up to 98.4% and 6.13 nm, respectively. The chemical composition was determined using a Fourier transform infrared (FT-IR) spectroscope. Thermal characterization of thermogravimetry analysis (TGA), derivative thermogravimetry (DTG), and differential thermal analysis (DTA) was conducted to identify the thermal stability and cellulose pyrolysis behavior of both J-MC and J-CNC samples. The thermal analysis of J-CNC indicated lower thermal stability than J-MC. It was noted that J-CNC showed higher levels of crystallinity and larger crystallite sizes than J-MC, indicating a successful digestion and an improvement of the main crystalline structure of cellulose. The X-ray diffraction spectra and TEM images were utilized to establish that the nanocrystals' size was suitable. The novelty of this work is the synthesis of spherical nanocellulose with better properties, chosen with a rich source of cellulose from an affordable new plant (studied for the first time) by stepwise water-retted extraction, continuing from our previous study.

Geosciences in thermal analysis development.- Differential scanning calorimetry and its applications to mineralogy and the geosciences.- Variable atmosphere thermal analysis - methods, gas atmospheres and applications to geoscience materials.- Measurement of different water species in minerals by means of thermal derivatography.- The determination of hydrated sulphates in the weathered crystalline rocks by means of thermal analysis.- Internal thermal reactions of minerals.- Kinetical study of mineral reactions by means of controlled transformation rate thermal analysis (CRTA).- Thermoanalytical investigations of binary oxide systems.- Kinetic analysis of the crystallization of silicate melts by means of DSC, DTA and thermal optical methods.- Application of thermal analysis in mineral technology.- Thermal investigations in technical mineralogy.- Application of thermal methods in raw material control and during the production process.- A study of the thermal behaviour and geotechnical properties of a marine clay and its composites.- Thermal analysis of selected illite and smectite clay minerals. Part I. Illite clay specimens.- Thermal analysis of selected illite and smectite clay minerals. Part II. Smectite clay minerals.- Remarks on the applicability of thermal analysis for the investigations of clays and related materials.- Differential thermal analysis (DTA) of organo-clay complexes.- Thermal analysis in environmental studies.

Among the methods of obtaining hematite (α-Fe2O3), the thermal decomposition of goethite (α-FeOOH) or iron (III) nitrate (Fe(NO3)3·9H2O) is of special importance. These solids can be combined with other materials, thus altering the properties of the oxide obtained. The decomposition of goethite or nitrate mixture with biomass in an inert atmosphere yields hematite/carbonaceous material or magnetite/carbonaceous composites with different morphologies and crystallinities, as observed by scanning electron microscopy and X-ray diffraction, respectively. The transformation of hematite to magnetite occurs at 623 K (for biomass/nitrate mixture) and 723 K (for biomass/goethite mixture). The formation of magnetite is a consequence of the pyrolysis of biomass, which produces a reducing mixture, and the difference in the temperature for obtaining Fe3O4 for the two precursors was investigated by thermal analysis by observing the mass and energy variations at each stage.

The thermal crystallization behavior of bulk Se90� xTe10Cdx (x ¼ 0, 3, 9, and 15 at%) glasses was studied by differential thermal analysis, (DTA), under non-isothermal conditions. The glass transition temperature, (Tg), the onset crystallization temperature, (Tc), and the peak temperature of crystallization, (Tp), were found to be dependent on both the composition and the heating rates. From the dependence on the heating rates (� )o f (Tg) and (Tp), the activation energy for the glass transition, (Et), and the activation energy for crystallization, (Ec), were calculated and their composition dependence is discussed. The crystalline phases resulting from DTA and scanning electron microscopy (SEM) have been identified using X-ray diffraction. The results indicate one dimensional growth from the surface to the inside for all the studied compositions. The kinetic parameters determined have made it possible to discuss the glass forming ability. (doi:10.2320/matertrans.MC200928) The study of the crystallization kinetics of a glass upon heating can be undertaken in several different ways. In calorimetric measurements two techniques have been em- ployed for the study of the crystallization behavior upon heating, namely isothermal and non-isothermal crystalliza- tion analyses. 6,7) In the isothermal method, the sample is brought quickly to a temperature above the glass transition temperature, Tg, and the heat evolved during the crystalliza- tion process at a constant temperature is recorded as a function of time. In the other method, the sample is heated from room temperature, at a fixed heating rate (� ), and the heat evolved is again recorded as a function of temperature. The present work is concerned with the study of the crystallization kinetics and the evaluation of the crystalliza- tion parameters for Se90� xTe10Cdx (x ¼ 0, 3, 9 and 15 at%) chalcogenide glasses by using the non-isothermal method. The effect of composition on the crystallization mechanism has been reported. 2. Experimental The bulk materials of Se90� xTe10Cdx (x ¼ 0, 3, 9 and 15 at%) were prepared by the usual melt quench technique; the highly pure materials (99.999%) were weighted accord- ing to their percentages and sealed in evacuated silica tubes which were heated at 900 � C for 20 h. During the melt process the tube was frequently rocked to intermix the constituents and to increase homogenization of the liquid. This treatment was followed by quenching in an ice/water mixture. The amorphous nature of the sample was proved by X-ray diffraction. Differential Thermal Analyses (DTA) was carried out by using a DTA Perkin-Elmer DTG-60 under non-isothermal conditions. The glass transition temperatures (Tg), the onset crystal- lization temperatures (Tc), and the peak crystallization temperatures (Tp), were determined with an accuracy of � 1 K using the microprocessor of a thermal analyzer. The crystallized fraction (� ) was calculated using the partial area analysis. For scanning electron microscopy (SEM) examina- tion, sample surfaces were etched using a mixed solution of sodium hydroxide and hydrogen peroxide. The X-ray diffractometer, Philips type 1710, was used to identify the crystalline phases in the annealed glassy samples.

Thermal analyses [thermogravimetry (TG) and differential thermal analysis (DTA)], X-ray diffraction, and infrared absorption analysis of bones from ovariectomized rats were carried out. The rats were divided into five groups: sham operated (Sham); ovariectomized (OVX); OVX given traditional Chinese (Kampo) medicine, Unkei-to; OVX given 17 beta-estradiol; and OVX given the estradiol vehicle, respectively. The activation energy (delta E), a kinetic parameter from TG data of OVX rats, increased by 57% from that in Sham rats. The administration of Unkei-to and 17 beta-estradiol to OVX rats clearly restored the delta E to the levels of Sham rats, while the vehicle for 17 beta-estradiol had no effect. DTA data from thermal analyses of rats from the Sham, OVX, and OVX given various compounds were almost the same except for OVX rats given 17 beta-estradiol. The X-ray diffraction pattern and infrared absorption spectrum of bone powders from Sham rats were not different from those of OVX rats or others. These results strongly suggest that kinetic parameter, delta E calculated from TG data, may be a useful method for assessing both experimentally induced osteoporosis and drug effects on it.

The core–nanoshell composite materials with magnetic fly-ash hollow cenosphere as core and nano SmFeO3 as shell were synthesized by high-energy ball milling method. The magnetic fly-ash hollow cenosphere, samarium nitrate, and iron nitrate were used as raw materials. The synthesis and growth kinetics of the composite materials were investigated using the thermogravimetry and differential thermal analysis (TG–DTA) at different heating rates. The results show that the precursor of the composite materials decomposes in three steps. The apparent activation energy of each stage was calculated using the Doyle–Ozawa and Kissinger methods. The reaction order, frequency factor, and rate equations were also determined. The activation energy of the nano crystallite growth is calculated to be 16.12 kJ mol−1 according to kinetics theory of nano crystallite growth. It can be inferred that the crystallite grows primarily by means of an interfacial reaction during the thermal treatment. The magnetic properties and microwave absorbing properties of samples were analyzed by the vibrating sample magnetometer analysis and vector network analyzer. The results indicated that the exchange coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating, which cause outstanding magnetic properties. In the frequency between 1 MHz and 1 GHz, the absorbing effectiveness of the composite absorbers can achieve −32 dB. The magnetic properties of the composite material are better than those of single phase. So it is consistent with requirements of the microwave absorbing material at the low-frequency absorption.

The composition Bi4Sr3Ca3Cu4−xNaxO16 for x=0.2, 0.4, 0.6, 0.8 and 1.0 was examined, in order to study the effect of Na/Cu substitution on both the glass-forming ability as well as the superconducting properties of the glass-ceramic (GC) phase. Because the GC phase of the composition Bi4Sr3Ca3Cu4O16 (4334) showed superconducting properties below 78.5 K, the crystalline phases formed after heat treatment were identified by X-ray diffraction. This suggests that Na+ substituted the Cu+ cations. The GC phases were studied by X-ray diffraction, differential thermal analysis, infrared absorption, d.c. electrical conductivity and low-temperature a.c. magnetic susceptibility in the temperature range 77–300 K. The present results support the considerations that the addition of sodium enhances the crystallization of the 4334 phase while sacrificing the glass-forming ability. The crystalline phases precipitated from the rapidly quenched glasses in the Bi-Sr-Ca-Cu-Na-O system were greatly dependent on the heat-treatment time as well as the treatment temperature. The stability and crystallization process of the glass differ greatly depending on the sodium content which acted as fluxing agent. Considering that the formation of the 4334 phase is largely enhanced in sodium-doped samples, it is concluded that the lowering of the partial melting temperature is very important for the enhancement of the formation of the 4334 phase, as well as in raising the critical transition temperature. Infrared spectroscopy measurements indicate that part of the ceramic phase is non-metallic. The two-probe method and the standard four-point probe method electrical resistivity indicate that Bi-Sr-Ca-Cu-Na-O superconductor formation was greatly dependent on heat-treatment time as well as treatment temperature. The superconducting crystalline phase, which grew upon heat treatment, was identified as a quasi-tetragonal phase 4334. Electrical resistance measurements together with thermopower results indicate that the electrical properties move from a metal region to a semiconducting region according to the magnetic phase diagram of oxide superconductors. Superconducting 4334 phase with Tc=84 K could be successfully prepared by the GC techniques within 1–2 h thermal cycling, which renders a great saving in processing costs and is a simple method of moulding superconducting articles.

Composites of novel biodegradable copolyamides based on adipic acid, 1,6-hexane diamine and l-proline with short E-glass fibres: 1. Preparation and properties