Thermal Transformation Behavior Research Articles

Effects of blackberry (Rubus spp.) polysaccharide on the structure and thermal behavior of the myofibrillar protein of chicken breast meat

Blackberry crude polysaccharides (BCP) was added to chicken breast to inspect the intermolecular interaction with myofibrillar protein (MP). The influence of BCP on the thermal transformation behavior and protein micro-structure during temperature rise period was studied. The results showed that the interaction between BCP and MP was mainly affected by the concentration of BCP and heating temperature. The results of infrared spectrophotometer and nano-particle/zeta potentiometer showed that a BCP-MP complex was generated through hydrogen bond and electrostatic interaction, which could promote the transformation of MP from β-folding to β-Angle transformation. The fluorescence spectra showed that the BCP was helped to the spread of protein structure of the MP. Moreover, synchronous thermal analyzer and rheometer results revealed that the BCP increased the enthalpy value and elastic modulus of MP. Scanning electron microscope verified pores inside the BCP-MP complex are more evenly distributed and smaller, which led to the high cross-linking of network and good stability of water distribution for the MP. The addition of BCP enhances the hydrogen bonds and disulfide bonds of MP molecules, which can strengthen the network structure and ultimately improve the performance of meat products.

Investigation of oxygen-enriched atmosphere combustion of oily sludge: Performance, mechanism, emission of the S/N-containing compound, and residue characteristics

It is an indispensable and important link to increasing the harmless treatment of oily sludge at the end of the petrochemical production stage to achieve the goal of clean production. This paper comprehensively investigates the thermal transformation behavior and the release of gaseous pollutants (VOCs, NOx, and S-containing gas) of petrochemical oily sludge. The results show that Petroleum hydrocarbons composed of C6–C35 can be effectively removed in the temperature range of 241–607 °C. It is worth noting that since low boiling point components such as benzene and toluene in the oily sludge may volatilize rapidly near the initial combustion temperature and generate toxic and harmful gases. For example, in this study, the toluene vapor signal could be observed before the initial combustion temperature and the toluene vapor signal appeared neatly around 350 °C and did not participate in the combustion reaction and the strong fluctuation of benzene vapor. Organic sulfur dominated by Sulfonate-S, Sulfoxide-S, and Aromatic-S could be released in the form of SO2 around 250 °C and 450 °C, while organic nitrogen dominated by Pyridinic-N, Protein-N, and Pyrrolic-N could be released in the form of NOx between 300 °C and 500 °C, which is mainly related to the thermal stability of sulfur-containing groups.

Co-hydrothermal carbonization of oil shale and rice husk: Combustion, pyrolysis characteristics, and synergistic effect.

Countries all over the world are looking for fuel to replace fossil energy due to environmental concerns and a scarcity of fossil fuels. Oil shale (OS) and rice husk (RH) are both viable fuels, although they both have issues like high ash content and poor calorific value. OS and RH were used as feedstock for high-quality fuel in this study, which uses a hydrothermal technique to provide a novel way to utilize OS and rice. At different hydrothermal temperatures (150, 200 and 250 °C), including combustion and pyrolysis processes, the thermogravimetric analyzer (TGA) was used to analyse thermal transformation characteristics of co-hydrothermal carbonization (co-HTC) of OS and RH, as well as the synergistic effects. Results showed that the co-HTC pretreatment had a significant effect on the thermal transformation behaviour of OS and RH. On the one hand, the co-HTC has higher volatile content than its calculated value. On the other hand, a synergistic effect was found in combustion processes, and this effect was the most obvious when the hydrothermal temperature was around 200 °C, and the characteristic peak of functional groups vibration was strong. Therefore, the co-HTC was considered suitable for combustion. The combination of co-HTC modification with subsequent thermochemical processes has positive implications for the energy production and utilization of organic waste.

The thermal transformation behavior and products of pyrite during coal gangue combustion

Pyrite is a common and important mineral in coal and coal gangue, and its thermal transformation behavior and products during combustion have an essential impact on the environment, coal combustion technology, and recycling utilization of coal ash and coal gangue. Two samples of coal gangue containing high pyrite content were studied using XRD, TG-MS, SEM-EDS, and TEM to reveal pyrite's thermal transformation behavior and products during coal gangue combustion. The results showed that pyrite was transformed into hematite nanospheres during coal gangue combustion in air and released SO2 gas in the process. The transformation proceeds in the sequence of pyrite (0 ∼ 400 °C) – nano-microspheric magnetite and jarosite (400 ∼ 500 °C) – nano-microspheric hematite (500 ∼ 1000 °C). Nano-hematite possessed the morphology of a nanospheric pseudomorph of magnetite. Nano-magnetite and jarosite as intermediates were transitional and unstable and formed in a weakly reducing–weakly oxidizing environment. The formation and thermal decomposition of jarosite was associated with the release of structural water from kaolinite dehydroxylation. During the phase transition reaction, SO2 was released twice: the first release was related to the formation of magnetite and jarosite, while the second release was related to the thermal decomposition of jarosite. Temperature was the main factor affecting the nanocrystallization of hematite, whose crystallinity improved with an increase in temperature. This research portrays a new thermal phase transformation mechanism of pyrite in coal gangue, which can provide a theoretical basis for the recycling of coal gangue.

The Thermal Transformation Behavior and Products of Pyrite During Coal Gangue Combustion

The Thermal Transformation Behavior and Products of Pyrite During Coal Gangue Combustion

Thermal Transformation of Oxide and Hydroxide Minerals in Chromite and Manganese Ores

Steelmaking industries consume the majority of chromium and manganese ferroalloys to impart several properties in steel and also for other purposes. The quality of ore governs the process kinetics as well as the process economy of the ferroalloy industry. The present study demonstrates the thermal transformation behavior of chromite and manganese ores with varying compositions. Simultaneous thermal analysis (DTA/TG) is employed for such ore samples where the transformation of mineral phases is correlated with the thermogram characteristics and quantified. Phase, microstructure, and compositional analysis results of individual ores corroborated with thermal analysis are in good agreement. Chromite samples are ferruginous with goethite and gibbsite contents, whereas manganese ores vary in composition and also exhibit multiple and/or overlapping transformations.

Electromagnetic and thermal behavior of a single-phase transformer during Ferroresonance considering hysteresis model of core

Ferroresonance leads to a high saturation of the transformer core. This causes severe rise of the amplitude of current and voltage of the transformer and leads to current and voltage non-sinusoidal waveforms. Therefore, the increase of the transformer losses and its temperature rises during Ferroresonance can overstress the transformer insulation system and elevate the chance of the transformer failure. In this paper electromagnetic and thermal behaviors of the transformer during Ferroresonance are investigated using a three dimensional finite element model. The modeling of the core is the most important challenge in the solution of the transformer electromagnetic equations during Ferroresonance. Thus, the Jiles-Atherton (JA) model is employed to model the core hysteresis loop. Based on the proposed approach, the behavior of a single-phase transformer under fundamental and sub-harmonic Ferroresonance modes are simulated and the results are compared with the experimental results. Furthermore, a thermal equivalent circuit is developed, based on the simulated transformer losses and thereby, the transformer temperature rises are estimated during Ferroresonance.

Structural, electrical, optical and morphological properties of aluminum-doped TiO2 thin films deposited by spray pyrolysis method

In this research, highly transparent thin films of pure and doped titanium dioxide (TiO2) with various amount of aluminum (0–5 mol%) were prepared by sol–gel method and were coated on a FTO substrate at 500 °C by spray pyrolysis. Thermogravimetry and differential thermal analysis were employed to study the thermal transformation behavior of the xerogel. The effects of aluminum doping on structural, morphological, optical, and electrical properties of TiO2 samples were evaluated using X-ray diffraction (XRD), field emission scanning electron microscopy, atomic force microscopy, UV–Vis absorption spectroscopy, ellipsometry and four point probe techniques. XRD results reveal that all thin films have anatase crystal structure and it can be seen that the preferred growth orientation of the TiO2 thin films depends on the Al doping levels. The results show that by increasing the amount of aluminum dopant (0 to 5 mol%), the grain size, crystalline plane distance and roughness are decreased, as well the resistivity of the TiO2 layers decreases until it reaches to a minimum value at 3 mol% of aluminum. On the other hand, the band gap rises from 3.28 to 3.39 eV. The ellipsometry measurements demonstrate that the refractive index of TiO2 thin films decrease from 1.96 to 1.89 at 632.8 nm and the extinction coefficient increase with Al doping content.

Mitigating crystallization of saturated FAMEs in biodiesel 6: The binary phase behavior of 1, 2-dioleoyl-3-stearoyl sn-glycerol – Methyl stearate

The derivatives of vegetable oils with specific chemical structures, such as TAG (triacylglycerols) having mixed straight and kinked moieties, have proven very effective in lowering the crystallization of biodiesel. SOO (1, 2-dioleoyl-3-stearoyl sn-glycerol)/MeS (methyl stearate) is part of a series of studies of TAG/FAME (fatty acid methyl ester) binary model systems conducted to establish structure–function relationships of lipid-based cold flow improvers in biodiesel with a particular attention to the effect of molecular symmetry in contrast with a previously published study of the OSO (1, 3-dioleoyl-2-stearoyl sn-glycerol)/MeS binary system. The phase behavior of several SOO/MeS mixtures were investigated at different length scales with XRD (X-ray diffraction), DSC (differential scanning calorimetry) and PLM (polarized light microscope). A complete phase diagram including the transformation lines, crystal structure and microstructure was constructed. The solubility behavior was discussed using a simple thermodynamic model based on the Hildebrand equation and pair interactions. The asymmetric position of the oleic moieties of SOO was shown to be crucial in modifying the thermal transformation behavior of MeS. The findings may be used to design effective crystallization modifiers of biodiesel based on particular structural determinants, and underscores the importance of symmetry in such designs.

Microstructural and mechanical properties of binary Ni–Si eutectic alloys

In the present work, Ni–Si eutectic alloys with nominal compositions of Ni80Si20, Ni70Si30, Ni55Si45 and Ni45Si55 (Ni and Si with the purity of 99.99%) were prepared by arc melting method under vacuum/argon atmosphere. The effects of Si/Ni ratio on the microstructural properties, thermal transformation behavior, micro-hardness and magnetic properties of the Ni–Si eutectic alloys were investigated. These alloys were characterized by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), differential thermal analysis (DTA), Vickers microhardness measurement and Vibrating Sample Magnetometer (VSM). The phases expected according to Ni–Si phase diagram for conventional solidified eutectic Ni–Si alloys are considerably consistent with phase detected by XRD in this study. The quantitative results confirm that the chemical composition of the alloys very close to eutectic compositions and the microstructures are in typical lamellar eutectic morphology. The maximum microhardness value of 1126HV obtained for Ni70Si30 alloy which has highest melting temperature amongst Ni–Si eutectics. The microhardness values decreases with increase of Si/Ni ratio. Ni80Si20 and Ni55Si45 alloys are soft ferromagnetic, Ni70Si30 and Ni45Si55 alloys are paramagnetic with no magnetic saturation.

An insight into the changes in the thermal analysis curves of boehmite with mechanical activation

This study deals with the changes in the thermal transformation behaviour of boehmite with mechanical activation (MA), carried out in planetary mill. Observed changes in the TG-DTG–DTA curves are: shifting of the desorption of physically adsorbed water to higher temperature, decrease in the γ-Al2O3 transformation temperature and its peak area, formation of α-Al2O3, not observed for unmilled boehmite upto 1,200 °C, for milling time ≥60 min. Reasons for such changes are explored on the basis of physicochemical changes occurring as a result of high energy milling. Structural degradation is found to increase with increase in milling time. As a consequence of structural changes, Al–OH bonds get stronger, whereas the hydrogen bonds get weaker. Stronger Al–OH bonding and enhanced surface energy increase water affinity and delays its removal. Decreased hydrogen bond strength, easy exit of dehydroxylation product (water) and displacement of Al to tetrahedral positions make the γ-Al2O3 transformation easier. Ease of removal of residual hydroxyls from small crystallite transition alumina from MA boehmite, as a result of shorter diffusion path, ensures α-Al2O3 transformation at lower temperature.

Thermal and Structural Analysis of Asphaltine in Heavy Oil before and after the Hydrogen Donor Catalytic Reaction of Upgrading and Viscosity Reduction under the Effect of Auxiliary Agents

This paper applies high-pressure reactor to simulate conditions of thermal recovery and uses formic acid as hydrogen donor body, self-made oil-soluble organic nickel salt as catalyst and urea as auxiliary agents to conduct the study on of heavy oil. By TG-DTA, IR and NMR spectra, it makes an analysis on thermal transformation behavior and structural changes of asphaltine in heavy oil before and after the reaction of upgrading and viscosity reduction under the effect of auxiliary agents. The results show that the stability of the asphaltine in heavy oil after aquathermolysis reaction of hydrogen donor catalyzing is decreased. Infrared spectroscopy analysis reveals that the absorption peaks of IR functional groups of asphaltine in heavy oil is unchanged and the addition of auxiliary agents basically does not change the structure of asphaltine. NMR structural analysis shows that.

Unexplored Thermal Transformation Behavior of Two‐Dimensionally Bound Gadolinium Hydroxide Layers: Fabrication of Oriented Crystalline Films of Gadolinium Oxychloride Nanosheets Suitable for the Multicolor Luminescence with Color Tunability

Unexplored Thermal Transformation Behavior of Two‐Dimensionally Bound Gadolinium Hydroxide Layers: Fabrication of Oriented Crystalline Films of Gadolinium Oxychloride Nanosheets Suitable for the Multicolor Luminescence with Color Tunability

Effect of sun radiation on the thermal behavior of distribution transformer

Abstract Performance and life of oil-immersed distribution transformers are strongly dependent on the oil temperature. Transformers, working in regions with high temperature and high solar radiation, usually suffer from excessive heat in summers which results in their early failures. In this paper, the effect of sun radiation on the transformer was investigated by using experimental and analytical methods. Transformer oil temperature was measured in two different modes, with and without sun shield. Effects of different parameters such as direct and indirect solar radiation on the thermal behavior of the transformer were mathematically modeled and the results were compared with experimental findings. Agreements between the experimental and numerical results show that the model can reasonably predict thermal behavior of the transformer. It was found that a sun shield has an important effect on the oil temperature reduction in summer which could be as high as 7 °C depending on the load ratio. The amount of temperature reduction by sun shield reduces as the load ratio of transformer increases. By installing a sun shield and reducing oil temperature, transformer life could be increased up to 24% in average.

Design of functionally graded NiTi by heat treatment

A novel design of the functionally graded near-equiatomic NiTi shape memory alloys that exhibit expanded ranges of transformation temperature and stress is developed. The approach utilises the sensitivity of the alloys' thermomechanical properties with respect to heat treatment conditions. The functionally graded properties are achieved by anneal within a temperature gradient after cold work, thus to create a continuous structural variation. The optimum annealing temperature range for the Ti–50.5 at.% Ni alloy is determined to be 630–800 K. Gradient-anneal of the alloy wire in this temperature range resulted in varying thermal transformation behaviour along its length and unique Lüders-type deformation behaviour with a positive stress gradient for both the forward and the reverse transformations. Such behaviour enhances the functionality of the alloy for actuation applications.

Low-density Mg-rich metallic glasses with bending ductility

Amorphous Mg–Cu–Ca(Y) alloys that contain more than 80 at.% magnesium and have a density as low as 1.8 g cm−3 have been prepared by melt spinning. Tension fracture strengths of ∼570 MPa are obtained for Mg85Cu5Ca10 ribbons, resulting in a specific strength of 300 MPa cm3 g−1. Scanning electron microscopy studies reveal dense river patterns on the fracture surface. The high Mg content and the thermal transformation behavior of these amorphous light alloys invite comparison to the Al-based metallic glasses.

Raman spectra and thermal transformations of ferrihydrite and schwertmannite

AbstractRaman and infrared spectra of 2‐line and 6‐line ferrihydrite and schwertmannite were recorded. The spectra of the ferrihydrites are compatible with octahedrally coordinated Fe3+. The spectra of schwertmannite are consistent with Fe(O,OH)6 octahedra in some of which an OH− ion has been replaced by a SO42− ion which acts as a bridging bidentate ligand to two Fe3+ ions. The Raman spectra show that under heating by the He–Ne laser beam 2‐line ferrihydrite and schwertmannite transform to hematite via a maghemite intermediate, whereas 6‐line ferrihydrite transforms directly to hematite. The different thermal transformation behaviour of the two ferrihydrites accords with recent reports that the two forms are structurally different and suggests that it is the disordered component of 2‐line ferrihydrite that transforms to maghemite on heating. In the case of schwertmannite the loss on heating of SO42− ions in the form of SO3 and H2O entails the simultaneous loss of OH− ions and the conversion of some OH− ions to O2−. The loss and resulting rearrangement of ligands around those Fe3+ ions originally liganded by SO42− results in a fraction of Fe3+ achieving the tetrahedral coordination that is associated with maghemite. Copyright © 2002 John Wiley & Sons, Ltd.

Preparation and investigation of sol–gel TiO 2–MnO

Sol–gel TiO 2–0.25MnO has been obtained using a colloidal solution. The thermal transformation behavior of the fresh xerogel was followed by simultaneous thermal analysis (STA) and powder X-ray diffraction (XRD). Sol–gel coatings were deposited by dipping and the successive dense films were optically characterized using UV–VIS–NIR spectrophotometry.

Ausforming of NiTi

Lattice defects are introduced into stable austenite (β) by hot rolling up to 70% (in one pass) in a temperature range between 900 > TAF > 340 °C (ausforming (AF)). The changes in microstructure, thermal transformation behavior, as well as normal and anomalous properties in stress-, strain-, and temperature-space were studied. Martensitic transformation temperatures are lowered with decreasing deformation temperature and increasing amount of deformation. A two-stage reaction is induced at TAF ≤ 400 °C. Deformation twins are the predominant microstructural feature, in addition to dislocations at TAF ≤ 700 °C. Highly elongated grains indicate that long-range recrystallization is absent at all ausforming temperatures. Semicoherent pecipitation in addition to high dislocation densities are likely to be responsible for the premartensitic anomalies of thermal transformation for TAF ≤ 400 °C. Ausforming leads to a considerable increase in conventional strength properties (yield stress, tensile strength, elongation) without loss of transformability and, consequently, shape memory or pseudo-elasticity.

Formation and crystallization of an acetate-acetylacetonate derived sol–gel BaTiO3

Abstract Sol–gel BaTiO 3 has been obtained using a colloidal solution prepared by peptization of an acetate derived gel with acetylacetone. The thermal transformation behaviour of the fresh xerogel was followed by simultaneous thermal analysis (STA) and powder X-ray diffraction (XRD). The crystallite size has been evaluated using transmission electron microscopy (TEM). A set of isothermal treatments was applied and thus the gel crystallinity was significantly affected as cubic BaTiO 3 resulted after direct heating up to 1300°C while a gradual cubic-to-tetragonal transformation of this sol–gel product occurred at the same temperatures but after a preliminary treatment at 400°C.