Differential Scanning Calorimetry Thermal Analysis Research Articles

Preparation of MoO3 powder by hydrothermal method

Abstract Based on the raw material of ammonium tetramolybdate in the experiment, molybdenum trioxide was prepared by hydrothermal synthesis, and the effects of different pH, hydrothermal reaction time, filling degree, and calcination temperature on molybdenum trioxide powder were studied. Meanwhile, the molybdenum trioxide powder was characterized through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and thermal analysis differential scanning calorimetry analysis so as to study the morphology and phase changes during the experiment. As is evident from the research findings, MoO3 powders with uniform and suitable size, smooth and clear surface, good dispersibility, and no adhesion can be obtained at the conditions of pH = 1, 16 h hydrothermal reaction, 90% of filling degree, and 550°C of calcination temperature. In the calcination process, MoO3 crystal undergone crystal transformation and was completely transformed from h-MoO3 to α-MoO3 at the calcination temperature of 350°C.

Cooling Damage Characterization and Chemical-Enhanced Oil Recovery in Low-Permeable and High-Waxy Oil Reservoirs

The well productivity of high-waxy reservoirs is highly influenced by temperature changes. A decrease in temperature can cause the precipitation of wax from the crude oil, leading to a decrease in the formation’s drainage capacity and a drop in oil production. In this study, the wax precipitation of crude oil is characterized by rheological properties tests and differential scanning calorimetry (DSC) thermal analysis. The wax damage characteristics of cores and the relative permeability curves at different temperatures were investigated through coreflood experiments. Furthermore, nanoemulsion is selected as a chemical agent for injection fluid. The nuclear magnetic resonance (NMR) scanning technique is used to investigate the effects of oil recovery enhancement at different pores by increasing temperature and adding nanoemulsion. By comparing the changes in T2 spectra and the distribution pattern of residual oil before and after liquid injection, the results have shown that both increasing temperature and adding nanoemulsion have a significant effect on oil recovery. The improvement of micropores is less pronounced compared to macropores. The produced oil mainly comes from the large pores. When the temperature is lower than the crude oil dewaxing point temperature, there is a serious dewaxing plugging phenomenon in the pores. Additionally, by observing the pattern of residual oil distribution at the end of the NMR online drive, it is hereby classified into wax deposition retention type, weak water washing retention type, and immobilized type, each with its own distinct characteristics. Wettability alteration and interfacial tension reduction can help to improve the drainage capacity of high-wax oil reservoirs, which is the main mechanism of nanoemulsion for enhanced oil recovery. These findings are highly valuable for enhancing the comprehension of the impact of highly waxed crude oils on drainage capacity and the ultimate oil recovery rate, particularly in relation to wax precipitation deposition.

Waste orange seeds (Citrus sinensis seed) transformation, a viable industrial bio-oil: Oil extraction, physicochemical characterization and vital instrumental analyses studies

The processing of Petroleum-based oil has contributed to environmental challenges such as climate change. Recently, research attention has been shifted to oil extraction from different non-edible seeds as a suitable substitute. Accordingly, this study examines the physiochemical characterization, and the effect of extraction temperature on the yield of waste Citrus sinensis seed [orange seed (OS)] bio oil. Studies on the prevalent functional group, fatty acid methyl ester compositions and thermal oxidative stability were carried out using the Fourier transform infrared spectroscopy (FTIR), gas chromatography-mass spectroscopy (GCMS) and differential scanning calorimetry (DSC), respectively. The oil content of the OS bio oil was 46.26%w/w. The high iodine number (31.47 mg/100 g) and low pour point (4.50 °C) of the OS bio oil showed its high content of unsaturated fatty acid. The FTIR functional group of the OS bio oil showed predominantly alkane of CH stretching, aldehydes, esters, and carboxylic acid. The chemical composition of the OS bio oil as determined by GCMS (massHunter/library/NIST 14.1) showed the occurrence of octadecadienoic and oleic acids as poly-saturated and saturated fat found in plant glycosides and vegetable fats and oil. The DSC thermal stability analysis showed the possible existence of mixed triglycerides. Finally, the result from the physiochemical characterization compositions, and functional group the OS bio oil indicated its potential as a suitable substitute for petroleum-based oil.

Enteric-coating film effect on the delayed drug release of pantoprazole gastro-resistant generic tablets.

Background: Enteric coating films in acidic labile tablets protect the drug molecule from the acidic environment of the stomach. However, variations in the excipients used in the coating formulation may affect their ability to provide adequate protection. This study is the first to investigate the potential effects of coating materials on the protective functionality of enteric coating films for pantoprazole (PNZ) generic tablets after their recall from the market. Methods: A comparative analysis was conducted between generic and branded PNZ products, using pure drug powder for identification. The in vitro release of the drug was evaluated in different pH media. The study also utilized various analytical and thermal techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and confocal Raman microscopy. Results: The in vitro assessment results revealed significant variations in the release profile for the generic product in acidic media at 120 min. DSC and TGA thermal profile analyses showed slight variation between the two products. XRD analysis exhibited a noticeable difference in peak intensity for the generic sample, while SEM revealed smaller particle sizes in the generic product. The obtained spectra profile for the generic product displayed significant variation in peaks and band intensity, possibly due to impurities. These findings suggest that the excipients used in the enteric coating film of the generic product may have affected its protective functionality, leading to premature drug release in acidic media. Additionally, the presence of polysorbate 80 (P-80) in the brand product might improve the properties of the enteric coating film due to its multi-functionality. Conclusions: In conclusion, the excipients used in the brand product demonstrated superior functionality in effectively protecting the drug molecule from acidic media through the enteric coating film, as compared to the generic version.

Clustering evolution during low temperature aging and thermal stability during two-step aging in Al-Mg-Si alloys

The age-hardening response during two-step aging in Al-Mg-Si alloys depends on the nanoclusters formed at the early stage of phase decomposition. However, understanding of the evolution and thermal stability of the nanoclusters is still lacking. This paper discusses clustering behavior during natural aging (NA) and pre-aging (PA) at 50 ℃ through various experiments [hardness, differential scanning calorimetry (DSC), electrical resistivity and three-dimensional atom probe (3DAP)]. A rapid increase in hardness is confirmed due to the acceleration of cluster formation during PA, and a larger area of an endothermic peak is confirmed during DSC thermal analysis compared to NA specimens. Hardness and electrical resistivity were clearly decreased in the PA specimens at the initial stage of two-step aging since the formation of thermally unstable clusters, the Mg-enriched clusters identified by 3DAP, was accelerated during PA. A long aging time at 50 ℃ produces Mg-enriched clusters rather than facilitating the transition from Cluster (1) to Cluster (2). To investigate the atomic arrangement of a cluster, we conducted further analysis for chemical composition of clusters through the normalization for the different sizes of cluster. We found that the Mg-rich clusters with the core-shell structure where Mg atoms are segregated around the cluster-matrix interface, cause thermally unstable at the initial stage of two-step aging. The direct experimental evidence primarily proves that atomic arrangement inside a cluster is a more critical factor than its size for the thermal stability of a cluster in Al-Mg-Si alloys.

Unveiling the strengthening mechanisms of as-cast micro-alloyed CrMnFeCoNi high-entropy alloys

The strengthening effects introduced by the addition of 2 at% titanium, vanadium, and niobium, as the well-known micro-alloying elements, to the model CrMnFeCoNi high-entropy alloy (HEA) were studied in the present work. Accordingly, the microstructure, mechanical properties, and strengthening mechanisms of the as-cast CrMnFeCoNi, (CrMnFeCoNi)98Ti2, (CrMnFeCoNi)98V2, and (CrMnFeCoNi)98Nb2 HEAs were investigated by electron-backscattered diffraction (EBSD), tensile testing, differential scanning calorimetry (DSC) thermal analysis, and theoretical calculations and measurements. Depending on the nature of the added elements and their segregation tendency during solidification, different degrees of microstructural refinement were observed in the as-cast ingots. The segregation tendency of Ti was found to be more pronounced compared to that of V (as predicted by the Scheil-Gulliver model), leading to a more refined secondary dendrite arm spacing (SDAS) and grains (resulting from the growth restriction factor and constitutional undercooling). Moreover, Nb addition led to the formation of the (Cr,Fe,Ni)2(Nb) Laves phase at the last stages via the eutectic solidification. The effect of the Laves intermetallic compound (type C14) and twinning-induced plasticity (TWIP) effect on the strength-ductility synergy was discussed. Moreover, a detailed modeling of the strengthening mechanisms revealed that the grain boundary strengthening (represented by the Hall-Petch relationship) and solid solution hardening (due to the lattice distortion) were the primary contributors to the increase in yield strength of V- and Ti-containing HEAs. On the other hand, the formation of the Laves phase, besides solid solution and grain boundary strengthening mechanisms, could lead to a considerable increase in the yield strength of the Nb-containing sample; although it would deteriorate the ductility of the alloy, as also discussed based on its brittle fracture surface appearance and the presence of micro-cracks. Accordingly, the present study is applicable to the design of modified Cantor-based HEAs.

Thermodynamic behavior of bioactive glass in relationship with high fluorine content

Fluoride (F) is important for enhancing illogical activity of bioceramics. To increase fluoride content of derived Hench bioactive glass (BaG), bioactive fluorosilicate glasses (BaG-Fx) were synthesized by using melting method and characterized using different physico-chemical analyses. Fluoride-containing BaGs were synthesized at a temperature of 1350°C. Structural and thermal effect of calcium fluoride (CaF2) insertion into the glass network in the BaG: SiO2–CaO–Na2O–P2O5 quaternary system was studied. Indeed, the incorporated amounts of fluorine (CaF2) (from 5% to 20% by mass) induced significant physico-chemical changes. Through the structural study by X-ray diffraction (XRD), the amorphous character of our fluorosilicate glasses is proven. Infrared (IR) spectroscopy proved the incorporation of fluorine into the glass matrix. In the microstructural framework, we revealed the morphological changes of the glass powders as a function of the CaF2 content. These results were confirmed by Brunauer, Emmett and Teller (BET) measurements. Through Differential Scanning Calorimetry (DSC) thermal analysis we established the impact of fluoride ions on the structural dynamics and thermodynamic properties of these newly developed bioactive glasses. Accordingly, it was possible for the first time to incorporate as much as 20 wt% of CaF2 in BaG respecting the conditions of bioactivity and biodegradability required by Hench. After detailed analyses of the transformation entropies of BG-Fx as a function of the added CaF2 content, it can be stated that the intermolecular movements within the fluorosilicate network are more limited as a function of the added CaF2 amount. This slows down the ion exchange phenomena and subsequently the dissociation of the material in vitro, which can be anticipated to occur after implantation in vivo.

Preparation, Characterization and Evaluation of Flavonolignan Silymarin Effervescent Floating Matrix Tablets for Enhanced Oral Bioavailability.

The convenient and highly compliant route for the delivery of active pharmaceutical ingredients is the tablet. A versatile platform of tablets is available for the delivery of therapeutic agents to the gastrointestinal tract. This study aimed to prepare gastro retentive drug delivery floating tablets of silymarin to improve its oral bioavailability and solubility. Hydroxypropyl methylcellulose (HPMCK4M and HPMCK15), Carbopol 934p and sodium bicarbonate were used as a matrix, floating enhancer and gas generating agent, respectively. The prepared tablets were evaluated for physicochemical parameters such as hardness, weight variation, friability, floating properties (floating lag time, total floating time), drug content, stability study, in vitro drug release, in vivo floating behavior and in vivo pharmacokinetics. The drug-polymer interaction was studied by Differential Scanning Calorimetry (DSC) thermal analysis and Fourier transform infrared (FTIR). The floating lag time of the formulation was within the prescribed limit (<2 min). The formulation showed good matrix integrity and retarded the release of drug for >12 h. The dissolution can be described by zero-order kinetics (r2 = 0.979), with anomalous diffusion as the release mechanism (n = 0.65). An in vivo pharmacokinetic study showed that Cmax and AUC were increased by up to two times in comparison with the conventional dosage form. An in vivo imaging study showed that the tablet was present in the stomach for 12 h. It can be concluded from this study that the combined matrix system containing hydrophobic and hydrophilic polymers min imized the burst release of the drug from the tablet and achieved a drug release by zero-order kinetics, which is practically difficult with only a hydrophilic matrix. An in vivo pharmacokinetic study elaborated that the bioavailability and solubility of silymarin were improved with an increased mean residence time.

Optimizing In Situ Combustion with Manganese (II) Oxide Nanoparticle-Catalyzed Heavy Oil Oxidation

The combustion front is a crucial parameter in determining the efficiency of in situ combustion techniques during enhanced oil recovery. Nowadays, catalytic systems are widely believed to be an efficient tool to stabilize the combustion front. This study aimed to investigate the synthesis and catalytic activity of manganese (II) oxide nanoparticles in the high-temperature oxidation of heavy oils. The synthesis and catalytic activity of manganese (II) oxide nanoparticles in the high and low-temperature oxidation regions of heavy oil were investigated in this study. The obtained nanoparticles were characterized and studied by using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), thermogravimetric analysis (TG), nitrogen adsorption and desorption measurements, and differential scanning calorimetry (DSC) thermal analysis combined with the Kissinger isoconversional method. The obtained results showed that the synthesized nanoparticles had an average size of 17 ± 4 nm and a specific surface area of 38.2 ± 0.1 m2 g−1, with a pore size distribution of ~8 nm. The low and high-temperature oxidation processes’ activation energies were found to be 98.9 ± 0.7 kJ/mol and 151.9 ± 0.6 kJ/mol, respectively, in the presence of nanoparticles. However, these parameters were found to be equal to 110.1 ± 1.8 kJ/mol and 142.8 ± 8.3 kJ/mol, respectively, in the absence of nanoparticles. These data were processed further by calculating the corresponding reaction rates. The obtained results indicated that the rate of heavy oil oxidation was higher in the presence of the synthesized nanoparticles, which could play a critical role in stabilizing the combustion front in the in situ combustion process.

High porosity composite structures produced from poly(lactic acid)/hydroxyapatite microspheres using novel Dual Beam Laser Sintering method: Analysis of structural, mechanical and thermal properties

The paper discusses the applicability of the novel Dual Beam Laser Sintering (DBLS) method for processing of poly(lactic acid)/hydroxyapatite (PLA/HAp) composite powders. The composite microspheres were prepared using the solid-in-oil-in-water (S/O/W) emulsification technique. The three-dimensional structures made of composite microspheres with different filler content – 5 % and 10 % by weight of HAp were processed using DLBS that uses a new method of preheating the powder bed. The obtained results were compared to the case of pure PLA presented in our previous work.The quality of the powders was determined using Dry Laser Diffraction (DLS), X-Ray Computed Tomography (XCT), Revolution Powder Analysis (RPA) and Differential Scanning Calorimetry (DSC). The melt flow rate and the thermal conductivity of the microspheres were also determined. Conducted research shows that the morphology of the particle depends heavily on the HAp content which ultimately influences the powder flowability properties. Moreover, the properties of samples manufactured using DBLS were evaluated. The internal microstructure was reconstructed using XCT and the open porosity structures were revealed. The influence of both the porosity and the HAp reinforcement on the mechanical properties was observed. Additionally, a thermal DSC analysis was carried out, which allowed to assess how the filler and process parameters affect the degree of crystallinity of the obtained structures and the thermal degradation of the composite.In general, the presented study shows the possibility of designing part properties not only by means of the DBLS process parameters but also by influencing the powder material properties. Both raw material properties and process parameters affect the morphology of pores and therefore the mechanical properties of PBF processed material.

Preparation and Characterization of a Eutectic Mixture of Fenofibric Acid and Nicotinic Acid and Evaluatuion of In Vivo Antihyperlipidemic Activity

Fenofibric Acid (FA) is classified under Biopharmaceutical Classification System (BCS) class II due to its poorly soluble in water and high permeability. The present study aimed to prepare the eutectic mixture of FA with nicotinic acid (NA) and characterize its solid state properties and in vitro dissolution rate, along with its in vivo antihyperlipidemic activity. Solvent drop grinding was the method chosen to prepare the eutectic mixture of FA and NA. Solid-state properties were evaluated using thermal analysis Differential Scanning Calorimetry (DSC), crystallographic analysis Powder X-Ray Diffraction (PXRD), FT-IR spectroscopic analysis, and Scanning Electron Microscopy (SEM). To examine in vivo antihyperlipidemic activity, 16 male Swiss Webster rats were injected with 1% hyperlipidemia-inducing solution, followed by the oral administration of 9.45 mg/kg FA and NA (equivalent to 9.45 mg/kg FA), after which the decrease in cholesterol levels was measured. Two-way ANOVA was used to evaluate the data, followed by Duncan’s multiple range test (95% confidence interval). The results proved that FA formed the eutectic mixture with NA at a molar ratio of 6:4. The eutectic mixture of FA-NA had a better solubility and in vitro dissolution rate compared to intact FA, which also led to notably improved antihyperlipidemic activity.

Study on the Change Behavior of Fluorosilicone Rubber in RP-3 Kerosene

Fluorosilicone rubber has excellent high temperature oil resistance and has been widely used in high temperature oil media. The performance of fluorosilicone rubber will degrade with the length of oil immersion time. In this paper, through oil resistance test, hardness test, tensile test, infrared analysis, differential scanning calorimetry analysis and thermal weight loss analysis, the performance, structure and composition changes of fluorosilicone rubber FS6265 at 150°C and RP3 kerosene soaking process are studied. The results show that in 150°C, RP3 kerosene, the mass and volume of fluorosilicone rubber FS 6265 first increase and then decrease. The hardness and tensile strength gradually decrease with the increase of immersion time, the elongation at break tends to increase slightly and then decrease. The performance changes are mainly caused by swelling, filler migration, side chain rupture and cross-linking damage. The swelling in the early stage of immersion plays a major role, and the filler migration, side chain and cross-linking failure play a major role in the later stage.

Preparation, Encapsulation, and Performance Evaluation of Ternary Phase Change Materials for Building Envelope

Background. In order to make up for the defect that a single phase change material cannot meet the phase change temperature in a specific application field, three kinds of materials with higher phase change temperature are selected in this paper. Through the phase change material composite method, it was adopted to carry out step cooling curve test and differential scanning calorimetry (DSC) test, based on the second law of thermodynamics and the theory of phase equilibrium. DSC thermal analysis and Fourier transform infrared spectroscopy (FT‐IR) characterization were carried out. The phase change diatomite was used for packaging materials and durability evaluation. The results show that when TD‐MA : LA = 6.2 : 3.8, the phase transition temperature of the experimental ternary composite phase change material is 20.1°C. The adsorption of diatomite to phase change material (PCM) is only physical adsorption, and the thermal stability is good after 100 phase change cycles. The maximum mass loss rate of phase change diatomite encapsulated by phenylpropene emulsion and cement powder is only 0.65%, at last, this phase change diatomite is suitable for building envelope structure.

Electromagnetic evaluation of radar absorbing materials based on conducting polypyrrole and organic–inorganic nanocomposite of polypyrrole/kaolinite

AbstractThis paper presents a study of radar absorbing materials (RAM), based on conducting polymer polypyrrole (PPy) and organic–inorganic nanocomposite of PPy filled with lamellar structure kaolinite clay (PPy/Kao) for X‐band frequency range application. PPy was obtained via a chemical synthesis using doping agent chloride acid, lauric acid, and sodium dodecyl sulfate. The nanocomposites were produced via in situ polymerization, where the same experimental conditions were applied for PPy synthesis. The radar absorbing composite was obtained by mechanically mixing an epoxy resin matrix with the synthesized materials. The characterization was done using infrared spectroscopy, scanning electron microscopy (SEM), thermogravimetric analyses, and differential scanning calorimetry thermal analysis, and electromagnetic measurements. Kao in the nanocomposite was used to promote polymer anchoring, behaving as a host agent. SEM demonstrated that the synthesized nanocomposites produced growth morphology of interconnected nanoparticles in an almost spherical shape and mostly globular in a cauliflower shape, with homogeneous sizes and packaged structure. Results showed that the RAM obtained presented a good performance as an electromagnetic wave absorber, with thermal stability above 120°C and incident wave attenuation ranging from −10 to −33 dB (90%–99.9%) in the X‐band.

Halogen‐free flame‐retardant cable compounds: Influence of magnesium‐di‐hydroxide filler and coupling agent on EVA/LLDPE blend system morphology

AbstractObjective of this work was to deeper understand the influence of a grafted coupling agent in EVA/LLDPE based blends containing mineral filler acting as a flame‐retardant. EVA/LLDPE blends (50:50 phr) containing magnesium‐di‐hydroxide (MDH) were compounded. For comparison, parts (4%–5%) of LLDPE were substituted with MAA‐g‐LLDPE copolymer as a coupling agent. No influence of the coupling agent was observed by differential scanning calorimetry (DSC) thermal analysis. A strong influence of different filler ratios (0%–60%) was detected by rheological investigations. Morphological studies revealed significant differences in blend morphology and filler location caused by phase transition which is close to the 50:50 composition. The coupling agent improved the compatibility of the blend in that a reduced phase size could be observed. The addition of the coupling agent relocated the mineral filler from being mainly located in the EVA phase into the interphase and created a connection between both polymeric phases which resulted in improved thermo‐mechanical performance.

Hydration investigation of negative temperature concrete at early age based on low-field nuclear magnetic resonance

Few control indexes and detection methods have considered the microstructure properties of negative temperature concrete. As such, construction-focused quality control of negative temperature concrete is still a problem that needs to be solved. In this paper, low-field nuclear magnetic resonance (LF-NMR) was used to monitor the in-situ distribution and dynamical variation of liquid water content in cement paste at both thawed (20 °C) and frozen (−15 °C) states. Results showed that LF-NMR could determine the optimal antifreeze dosage and pre-curing time. LF-NMR was also able to evaluate the properties of negative temperature concrete at early stages, and these properties coincided with the results of compressive strength test. Both LF-NMR and differential scanning calorimetry thermal gravimetric analysis (DSC-TGA) revealed that the main positive effect of the antifreeze on negative temperature concrete is the alleviation of frost heave stress, and not the promotion of hydration. Additionally, a theoretical hypothesis was proposed to explain the reason why concrete with low water/binder ratio is more sensitive to freezing damage at the early stages.

Thermodynamic and kinetic interpretation of the glass-forming ability of Y-containing Cu-Zr-Al bulk metallic glasses

In the present study, the glass-forming ability (GFA) of (Cu50Zr43Al7)100-xYx (x = 0, 2, 4 and 6 at.%) bulk metallic glasses (BMGs) was investigated from thermodynamic and kinetic viewpoints. The amorphous structure of the alloys was confirmed using several techniques including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and differential scanning calorimetry (DSC). The thermal characteristics obtained through DSC and differential thermal analysis (DTA) were employed to establish a correlation between the GFA and thermodynamics/kinetics factors. The (Cu50Zr43Al7)98Y2 BMG has a promising GFA of 15 mm diameter, i.e. a 50% increase in GFA compared to the base alloy. Several GFA indicators (ΔTx, Trg, γ and K) confirm the excellent glass-forming capability of 2 at.% Y-doped BMG. The role of the optimum yttrium content in improving the GFA was scrutinized considering atomic, topological, and thermodynamics concepts. The interpretations imply that Y enhances the GFA through two main ways including promoting a more densely packed atomic configuration and also through scavenging oxygen as an undesirable element in glass-forming systems.

Analysis of DSC (differential scanning calorimetry) thermograms of milk fat

The object of current research is the oxidation and melting properties of milk fat samples in different heating rates. One of the most problematic issues is the evaluation dependence of temperature and oxidation time regarding to heat flow, and the estimation of attitude of enthalpy values to heating rates. In order to gain a comprehensive assessment of oxidation and melting properties of milk fat samples on differential scanning calorimeter in various heating rates, it is necessary to conduct experimental studies. The analysis was performed using the dynamic option of the differential scanning calorimetry (DSC) with the following sample heating rates: 2.5, 4, 5, 7.5, 10, 12.5, 15 °C⋅min–1. Analyses were performed on 14 samples of milk fat, thus, for each heating rate were intended to two milk fat samples. As a result of the analysis, in the proper heating rates increased, it was found, that the oxidation properties of milk fat depend on the heating rates on DSC examination. In the thermal DSC analysis, the start temperature (Ts) (inlet), the onset temperature (Ton), and the maximum heat flow-peak temperatures (Tp) of oxidation were rising gradually. All the value of oxidation increased gradually with increasing heating rate, only in the Tend values were chainable among all heating rates. However, the oxidation time of milk fat is inversely proportional to the various heating rates in DSC. The oxidation enthalpy was calculated according to the heating rates too. The masses of the samples differ from each other, albeit slightly, which the individuality in the value of enthalpy could be explained through this ratio and duration of exothermic. The melting point considers the important indicator to explain the purity of samples. Melting curves of extracted milk fat samples on DSC were characterized by endothermic behavior and observed with the mild peaks, the first and the second distinct peaks due to the low-melting triacylglycerols (with high unsaturated fatty acids content) and high-melting fats, which present in milk fat. In concluded results, the characteristics of DSC oxidation curves are melting point due to the chemical structure of the fatty acids which milk fat samples contain.

Amorphization, mechano-crystallization, and crystallization kinetics of mechanically alloyed AlFeCuZnTi high-entropy alloys

Equiatomic and non-equiatomic AlFeCuZnTi high-entropy alloys (HEAs) were prepared by high energy ball milling of elemental powders. For the equiatomic HEA with chemical composition at the boundary of solid solution and amorphous phase regions, an amorphous phase was obtained at moderate milling times, which was mechano-crystallized into a BCC solid solution by continued milling. For the non-equiatomic HEA with chemical composition well within the solid solution region, the same BCC solid solution was obtained during mechanical alloying. The crystallization kinetics of the amorphous HEA was studied by differential scanning calorimetry (DSC) thermal analysis. The crystallization activation energy (calculated based on the Kissinger equation) was correlated to the mean self-diffusion activation energy of the constituting elements, which was related to the multi-component nature of HEAs.

Thermally Activated Al(OH)3 Part II—Effect of Different Thermal Treatments

In this paper, the thermal decomposition of crystalline Al(OH)3 was studied over the temperature range of 260–400 °C for particles with a size between 10 and 150 µm. The weight losses and thermal effects occurring in each of the dehydration process were assessed using thermogravimetry (TG) and differential scanning calorimetry (DSC) thermal analysis. X-ray diffraction (XRD) patterns, refined by the Rietveld method, were used for mineral phase identification, phase composition analysis, and crystallinity degree determination. Moreover, the particle size distributions and their corresponding D10, D50, and D90 numeric values were determined with a laser analyzer. We observed a strong relationship between the calcination temperature, the initial gibbsite grade particle size, and the crystallinity of the resulting powders. Hence, for all endothermic effects identified by DSC, the associated temperature values significantly decreased insofar as the particle dimensions decreased. When the gibbsite was calcined at a low temperature, we identified small amounts of boehmite phase along with amorphous new phases and unconverted gibbsite, while the powders calcined at 400 °C gradually yielded a mixture of boehmite and crystalized γ-Al2O3. The crystallinity % of all phase transition products declined with the increase in particle size or temperature for all the samples.