Differential Thermal Calorimetry Research Articles

A comprehensive investigation on CdO-SnO2 system: Structure, thermal expansion and energetics

An extensive investigation into the thermochemical stability of two ternary oxides, ilmenite-type CdSnO3(s) and orthorhombic Cd2SnO4(s), in the Cd-Sn-O system was reported for the first time using high temperature oxide melt solution calorimetry in conjunction with differential scanning calorimetry and thermal relaxation calorimetry. The values of standard molar enthalpy of formation (∆fH298.15°), standard molar entropy (S298.15°), molar heat capacity and Debye temperature (θD) for ilmenite-type CdSnO3(s) and orthorhombic Cd2SnO4(s) were determined. Using the experimentally obtained thermochemical data, the standard molar Gibbs energy of formation of these compounds were derived and the corresponding expressions are given as follows:∆fGm°<CdSnO3>±1.3kJmol−1=−847.9+0.2781(T/K)(T:298.15−1000K)∆fGm°<Cd2SnO4>±3.6kJmol−1=−1138.1+0.3831(T/K)(T:298.15−1000K)Moreover, high temperature XRD experiments were conducted to evaluate their thermal expansion behaviour as well as for the in-situ identification of phase evolution resulting from decomposition of cadmium stannates.

Rheological Characteristics of Starch-Based Biodegradable Blends.

Thermoplastic starch was blended with commercially available biodegradable polyesters of poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) for its improved performance and processability. The morphology and elemental composition of these biodegradable polymer blends were observed by scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively, while their thermal properties were analyzed using thermogravimetric analysis and differential thermal calorimetry. For rheological analysis, the steady shear and dynamic oscillation tests of three samples at various temperatures were investigated using a rotational rheometer. All three samples exhibited significant shear thinning at all measured temperatures, and their shear viscosity behavior was plotted using the Carreau model. The frequency sweep tests showed that the thermoplastic starch sample exhibited a solid state at all temperatures tested, whereas both starch/PBAT and starch/PBAT/PLA blend samples exhibited viscoelastic liquid behavior after the melting temperature such that their loss modulus at low frequencies was greater than the storage modulus, and inversion occurred at high frequencies (storage modulus > loss modulus).

Preparation and Performance of Biodegradable Poly(butylene adipate-co-terephthalate) Composites Reinforced with Novel AgSnO2 Microparticles for Application in Food Packaging.

Biodegradable composites with antimicrobial properties were prepared with microparticles of silver stannate (AgSnO2) and poly(butylene adipate-co-terephthalate) (PBAT) and tested for applications in food packaging. The PBAT matrix was synthesized and confirmed by 1H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction (XRD). Ultrasonic and coprecipitation methods were used to synthesize AgSnO2. A two-step mixing method and a solvent cast technique were utilized to fabricate the PBAT composites (different weight % of AgSnO2) for packaging foods. Attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, XRD, and scanning electron microscopy were used to investigate the formation, structure, and size of the composites. Thermogravimetric analysis and differential thermal calorimetry were used to examine the PBAT/AgSnO2 composites. The best characteristics are exhibited in 5.0 wt. % AgSnO2 loaded PBAT composite. The tensile strength, elongation at break, water vapor transmission rate, and oxygen transmission rate were 22.82 MPa, 237.00%, 125.20 g/m2/day, and 1104.62 cc/m2/day.atm, respectively. Incorporating AgSnO2 enhanced the hydrophobicity of the PBAT materials as evaluated by the water contact angle. The 5.0 wt. % AgSnO2/PBAT film shows a favorable zone of inhibition against the bacteria pathogens S. aureus and E. coli, according to an evaluation of its antimicrobial activity. The weight loss of 5% AgSnO2/PBAT film was 78.4% after eight weeks in the natural soil environments. In addition, the results of food quality studies recommend that AgSnO2/PBAT (5.0 wt. %) film had a longer food shelf life than the neat PBAT and commercial, increasing it from one to 14 days for carrot vegetables.

Incorporation of Bentonite Mining Waste in Ceramic Formulations for the Manufacturing of Porcelain Stoneware

Mining processes produce a massive amount of waste which, if not treated properly, can cause significant environmental and social impacts. Recently, some studies have focused on the use of mining waste as an alternative raw material. This work developed new sustainable ceramic formulations based on bentonite mining waste (BMW) for applications in porcelain stoneware. The BMW was incorporated into the ceramic masses in different percentages (0, 2.5, 5, 10, 15, 20, 25, and 40 wt.%), in partial replacement to feldspar and total to quartz. X-ray diffraction (XRD), differential thermal calorimetry (DTA), and thermogravimetry analysis (TGA) techniques were used to characterize bentonite waste. Samples (50 mm × 20 mm × 5 mm) were obtained by uniaxial pressing. Such samples were dried and sintered at 1150, 1200, and 1250 °C. The physical–mechanical properties (apparent porosity, water absorption, linear shrinkage, apparent density, and flexural strength) were evaluated for sintered samples. The phases formed after sintering treatments were characterized by XDR and scanning electron microscopy (SEM). The BMW presented a mineralogical composition suitable for use as ceramic raw material. In summary, our results presented that the new sustainable ceramic formulations sintered at 1250 °C have the potential for use in stoneware and porcelain stoneware.

Experimental studies of the quasi-binary system Na2SO4–NiSO4 by differential thermal analysis, calorimetry and X-ray diffraction

This work is dedicated to experimental studies of the quasi-binary sub-system Na2SO4–NiSO4 with Differential Thermal Analysis (DTA) with simultaneous Thermal Gravimetry (TG), Differential Scanning Calorimetry (DSC), and X-ray Diffraction (XRD) to obtain the transition temperatures, the phase compositions, and thermodynamic data of Na2Ni(SO4)2, (Fp: 982 ± 3 K, ΔHfus = 59 ± 3 kJ mol−1), compound in this sulfate system. A compound Na6Ni(SO4)4) with the decomposition temperature 682 ± 3 K was confirmed. The lack in the data of the NiSO4-rich region was clarified. The entire composition range could be measured and the structure change at 1243 ± 3 K (“dkostruct”) that enables to describes corrosion processes on Ni-containing alloys in a sulphatic-rich environmental, as well as the melting point of NiSO4 at 1483 ± 3 K could be confirmed in this work. A new and complete phase diagram was determined.

Thermal Preprocessing of Rapidly Solidified Al 6061 Feedstock for Tunable Cold Spray Additive Manufacturing

In this work, the influence of thermal pre-processing upon the microstructure and hardness of Al 6061 feedstock powder is considered through the lens of cold spray processing and additive manufacturing. Since solid-state cold spray processes refine and retain microstructural constituents following impact-driven and high-strain rate severe plastic deformation and bonding, thermal pre-processing enables application-driven tuning of the resultant consolidation achieved via microstructural and, therefore, mechanical manipulation of the feedstock prior to use. Microstructural analysis was achieved via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, energy dispersive spectroscopy, and differential thermal calorimetry. On the other hand, nanoindentation testing and analysis were relied upon to quantify pre-processing effects and microstructural evolution influences on the resultant hardness as a function of time at 540 °C. In the case of the as-atomized powder, β-Mg2Si-, Al-Fe-, and Mg-Si-type phases were observed along polycrystalline grain boundaries. Furthermore, after a 60 min hold time at 540 °C, Al-Fe-Si-Cr-Mn- and Mg-Si-type intermetallic phases were also observed along grain boundaries. Furthermore, the as-atomized hardness at 250 nm of indentation depth was 1.26 GPa and continuously decreased as a function of hold time until reaching 0.88 GPa after 240 min at 540 °C. Finally, contextualization of the observations with tuning cold spray additive manufacturing part performance via powder pre-processing is presented for through-process and application-minded design.

Poloxamer188 composite electrospun poly L-lactic acid fibrous nonwoven: Sustained in vitro and in vivo release letrozole as a subcutaneous implant

Poloxamer188 composite poly L-lactic acid (PLLA) electrospun fibrous nonwovens (EFNW) were prepared by simple letrozole-poloxamer188-PLLA co-solution electrospinning and used as subcutaneous implants to sustained release letrozole. Contents of poloxamer188 and letrozole were varied to investigate the effect of the two compounds’ amounts on drug release behavior. Materials’ combination and drug incorporation in fibers were investigated by X-ray diffraction and differential thermal calorimetry. Letrozole contents in vitro and in vivo were all determined by high-performance liquid chromatography-ultraviolet spectrometry. Meanwhile, in order to analyze the mechanism of drug release behavior and show modulated drug release by electrospun fibers, letrozole-poloxamer188 solid dispersions (SDs) and letrozole-poloxamer188poly L-lactic acid-dichloromethane solution cast films (CFs) were also studied. Plasma letrozole concentration curves of subcutaneous implanting EFNW and daily oral administration of poloxamer188-letrozole SD on female rabbits were investigated and compared. Fibers of desirable morphology were obtained. During the whole release process of all EFNWs, water-insoluble letrozole could be released in the form of being dissolved. Letrozole release rates increased with increasing poloxamer188 content and decreased with increasing letrozole content. When letrozole and poloxamer188 content in fibers was 30% and 150% (EFNW-30-150%), respectively (with respect to PLLA in mass ratio), the release curve presented a desirable profile. After subcutaneous implant of EFNW-30-150%, the plasma concentration curve presented a later peak time and lower maximum value, and a comparable bioavailability with daily oral administration of poloxamer188-letrozole SD solution within 15 days. The research provided primary and encouraging information to use EFNW as a novel subcutaneous implant for sustained delivery of water-insoluble drugs.

Dual responsive tamarind gum-co-poly(N-isopropyl acrylamide-co-ethylene glycol vinyl ether) hydrogel: A promising device for colon specific anti-cancer drug delivery

In this study, pH and temperature-sensitive tamarind gum (TM)-based hydrogels were synthesized by free radical polymerization using a combination of acrylamide (AM), N-isopropyl acrylamide (NIPAM), and ethylene glycol vinyl ether (EGVE) monomers with bis (2-(methacryloyloxy) ethyl phosphate (BMEP) as a crosslinker (TANEB hydrogel). The prepared TANEB hydrogels were characterized by Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy to confirm the formation of functional group interactions and morphology. 5-Fluorouracil (5-FU) as a model drug was loaded into the TANEB hydrogels. Differential thermal calorimetry and XRD confirmed the molecularly loaded 5-FU into TANEB hydrogels. Swelling studies revealed the dual responsive nature of the TANEB hydrogels. An in vitro drug release study was performed at pH 1.2 and 7.4 and at 25 and 37 °C. The release time of 5-FU from the hydrogels was extended up to 12 h. Also, 5FU encapsulated hydrogels showed remarkable cytotoxicity against human colorectal adenocarcinoma cancer cells (HCT116 cells) along with good cell cycle ability. Thus, the TANEB hydrogel formulations could be used as potential delivery system for anticancer drugs.

TGA-DSC Combined Coal Analysis as a Tool for QC (Quality Control) and Reactivity Patterns of Coals.

Coal is at present a major fuel source for power generation worldwide and will remain as such in the near future. The most important property of coal that determines its price is its calorific value. However, volatiles, ash, and moisture content are also very important properties needed for the quality control (QC) of the coal used to maintain an optimal operation of coal combustion in a boiler. The determination of these properties is carried out via well-established ASTM/DIN methods, which are slow and time-consuming. This study uses combined thermogravimetric analysis (TGA)/differential thermal calorimetry (DSC) instrumentation as a tool to evaluate the reactivity patterns of the aliphatic versus aromatic content of coals, which is correlated to the volatile content of coals. Two coals, bituminous (American Baily Pittsburgh No. 6) used in Israeli utilities and lignite (brown coal Hambach) used in German power plants, have been investigated in this study. The results show that the combined TG/DSC method can provide a much better understanding of the chemical reactivity of coals in the combustion process.

Physicochemical Study of the Self-Disintegration of Calcium Orthosilicate (β→γ) in the Presence of the C12A7 Aluminate Phase.

The β-γ polymorphic transition of calcium orthosilicate (C2S) is a key phenomenon in cement chemistry. During this transition, the compound expands due to structural changes and a significant reduction in its density is observed, leading to its disintegration into a powder with a very high specific surface area. Owing to this tendency of the C2S material to “self-disintegrate”, its production is energy-efficient and thus environmentally friendly. A physicochemical study of the self-disintegration process was conducted with the aim of determining how the amount of dodecacalcium hepta-aluminate (C12A7) in calcium orthosilicate (C2S) affects the temperature at which the polymorphic transi-tions from α’L-C2S to β-C2S and from β-C2S to γ-C2S undergo stabilization. The applied techniques included differential thermal analysis (DTA), calorimetry and X-ray diffraction (XRD), and they made it possible to determine what C2S/C12A7 phase ratio in the samples and what cooling rate constitute the optimal conditions of the self-disintegration process. The optimal cooling rate for C2S materials with a C12A7 content of up to 60 wt% was determined to be 5 K·min−1. The optimal mass ratio of C2S/C12A7 was found to be 70/30, which ensures both efficient self-disintegration and desirable grain size distribution.

The effects of tantalum addition on the glass forming ability, thermal stability, and mechanical properties of Ni-Co-W-B bulk metallic glasses

The effects of Ta substitution for Ni and Co on the glass forming ability (GFA), thermal stability, and mechanical properties of (Ni0.592Co0.408)61.3-xTaxW23.7B15 (x=0-10) bulk metallic glasses were studied by differential thermal calorimetry (DSC), X-ray diffractometry (XRD), microhardness and compressive tests. Tantalum additions up to 8 at.% increases the GFA. The alloy containing 8 at.% Ta has the highest GFA and its critical thickness was determined to be 1.5 mm. It is also determined that the thermal and mechanical properties of the alloys improve with tantalum additions. The glass transition temperature increases from 854 K in (Ni0.592Co0.408)61.3W23.7B15 alloy to 971 K in (Ni0.592Co0.408)51.3Ta10W23.7B15 alloy. Also, microhardness increases from 1151 Hv for (Ni0.592Co0.408)61.3W23.7B15 alloy to 1262 Hv for (Ni0.592Co0.408)51.3Ta10W23.7B15 alloy. The compressive strength and elastic modulus of 8 at.% Ta containing alloy are 4.2 GPa and 204 GPa, respectively.

Transformation of non-firing technology issues for construction composite production from particulates using phosphogypsum

This paper presents the research results of the structure formation process of construction composites with the simultaneous extraction of a non-radioactive rare-earth metals concentrate in a non-fired technological process from a chemical production waste, phosphogypsum, which is being accumulated in dumps for years and causing damage to the environment. The article provides the results of the initial material studies by the X-ray fluorescence method, differential thermal calorimetry, and spectrometry on such aspects as radioactivity, chemical composition, dehydration energy. A flow chart of the energy-saving non-firing technology for the direct production of wall materials with a simultaneous extraction of the rare-earth metal concentrate from phosphogypsum is presented. When leaching the phosphogypsum, the concentrate, containing non-radioactive rare-earth metals, was obtained. It has been shown that phosphogypsum can be used as a construction material without restrictions on radioactivity. Laboratory research and verified technology proved the phosphogypsum exhibits astringent properties that provide the production of wall materials by non-firing method with the simultaneous extraction of the rare-earth metal concentrate. The developed technology makes it possible to separate strategically important rare-earth metals from the phosphogypsum while reducing the cost of production of wall materials by 2 … 3 times.

The effect of rare earth element (Er, Yb) doping and heat treatment on suspension stability of Y2O3 nanoparticles elaborated by sol-gel method

Sol–gel processing was used to fabricate undoped and rare-earth (Er, Yb) doped very fine Y2O3 nanoparticles under supercritical drying conditions of ethanol using an autoclave and annealed at 500 °C and 800 °C for 2 h. The Er and/or Yb concentration is fixed at 5 mol % for doped and co-doped nanoparticles. The as-synthesized Y2O3 nanopowder was characterized by the X-ray diffraction, scanning electron microscopy and thermogravimetric analysis (TGA) coupled with differential thermal calorimetry (DTA). The effects of solvent, heat treatment and the doping on the suspension stability of yttrium oxide (Y2O3) nanoparticles doped rare-earth elements (Er and Yb) were evaluated by UV-Visible spectroscopy, zeta potential measurement and particle size in suspension, thus, Hamaker 2 software. During this work, the particle analysis showed that the resulting nanoparticles had a pure cubic structure and nano-sized crystallites of about 8–38 nm. The heat treatment of the nanopowders causes a rapid decantation of the suspensions and the Er doped nanoparticles suspension had a good stability.

Peculiarities of foam glass synthesis from natural silica-containing raw materials

The production of foamed silicate materials using foam glass technology promotes using of environmentally friendly fire-resistant heat-insulating materials. At the same time, it is urgent to search for different silicate materials, which could be used instead of common glass powder. A new promising way to produce foamed silicate materials is “hydrate” foaming. It is based on an interaction between SiO2 and alkali solution with a formation of sodium hydrosilicate mixture. Further heating leads to a water vapor release that forms the softened silicate mass. This study describes the technology of preparation and heat treatment of initial raw mixtures, their synthesis, the properties of the synthesized samples (density, porosity) and their internal structure. A comparative analysis of the processes occurring during the heat treatment of the initial diatomite and the developed compositions was performed. The processes occurring during foaming of foam glass using a “waterglass–glycerol” mixture were considered using differential thermal calorimetry. The role of each component of the mixture was revealed, and the perspective of their introduction was justified, as it allows obtaining a material with a density of 190 kg m−3.

Investigation of long-term ageing effect on the thermal properties of chicken feather fibre/poly(lactic acid) biocomposites

In this study, the effects of long-term natural atmospheric ageing on the thermal properties of chicken feather fibre reinforced poly(lactic acid) biocomposite materials having chicken feather fibre mass content of 2, 5, and 10% were investigated. Chicken feather fibres, which are bio-based reinforcement material, and poly(lactic acid), which is bio-based matrix material, are compounded with a twin-screw extruder and injection-moulded; hence, the biocomposite material is produced. The effect of long-term natural atmospheric ageing on the thermal stability, crystallization, and melting behaviour of the biocomposite materials were analysed by thermogravimetric, derivative thermogravimetry, differential thermal, and differential scanning calorimetry analyses. In addition, the fracture surface of the samples was examined in depth by scanning electron microscopy analysis. The experimental results show that the long-term natural ageing process decreases the thermal stability values of the biocomposite materials and increases the glass transition temperatures and degree of crystallinities.

Effect of firing temperature waste from water treatment on sorption characteristics of petroleum products

The article reflects the results of research on the influence of roast temperature of water treatment waste obtained from drinking water generation (at the water treatment plant in Nizhnekamsk, Republic of Tatarstan) for sorption characteristics for native and used oil products - oils 5W40, 15W40 and И-20А. The methods of instrumental and computational means of research are presented. Differential thermal analysis and differential scanning calorimetry of water treatment waste were performed. The graphs of the influence of roast temperature on the aqueous extract pH value, maximum oil capacity and water absorption were constructed. It was found that at high temperatures, the decomposition of organic compounds with formation of carbon black occurs. It increases the maximum oil capacity in dynamic and static conditions in water and water absorption. It is determined that the best adsorption indicators are achieved for a sample of water treatment waste subjected to heat treatment at 600 C.

Structure-forming role and properties of phosphogypsum in unburned technology of wall materials and rare-earth metals concentrate simultaneous production

The paper presents the theoretical aspects of the processes of structure formation of composites in the non-fired technology for producing building wall materials with the simultaneous extraction of a concentrate of non-radioactive rare-earth metals from phosphogypsum. The object of research is phosphogypsum – an environmentally-adverse chemical waste that accumulates in dumps over the years. The research results are illustrated with the X-ray fluorescence method, differential thermal calorimetry and spectrometry of the properties of phosphogypsum: radioactivity, chemical composition, dehydration energy, content of non-radioactive rare-earth metals. The effect of dehydration energy and pressure on the strength of the resulting building material is established. A flow chart of energy-saving non-firing technology for the direct production of wall materials with the simultaneous extraction of a rare-earth metal concentrate from phosphogypsum is presented. It has been shown that phosphogypsum can be used as a building material without radioactivity restrictions. It is proved that phosphogypsum exhibits astringent properties that provide annealing-free production of wall materials with the simultaneous extraction of a rare-earth metal concentrate. This technology allows for the selection of strategically important rare-earth metals from phosphogypsum while reducing the cost of production of wall materials by 2 - 3 times.

Investigation of microstructural, mechanical and corrosion properties of graphene nanoplatelets reinforced Al matrix composites

Graphene nanoplatelets (GNP) were utilized as reinforcement for Al matrix with the aim of exploiting its extremely high mechanical properties. GNP reinforced composites were prepared via powder metallurgical processing route based on mechanical alloying, cold pressing and pressureless sintering. 0.5 to 2 wt% of GNP were incorporated into the aluminum via mechanical alloying up to 8 h in a high-energy ball mill. The mechanically milled powders were compacted by two different methods as uniaxial cold pressing and cold isostatic pressing. The prepared powders and bulk samples were characterized by differential thermal calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX), optical microscopy (OM), and Archimedes density, microhardness and dry sliding wear tests. Additionally, corrosion properties of the Al-GNP composites were determined by the Tafel exploration method. The results showed that the optimum GNP amount could be expected as 0.5 wt%, which enhanced the microhardness and wear resistance values of the Al from 84.5 ± 1.98 HV and 0.7384 mm3 to 199.4 ± 1.88 HV and 0.4476 mm3, respectively. However, this amount of graphene addition tended to slightly deteriorate the corrosion resistance of Al.

Potential application of fish scales as feedstock in thermochemical processes for the clean energy generation

The replacement of fossil fuels by renewable sources has been discussed globally, because fossil fuels account for a large portion of the pollutant emissions into the atmosphere. Several cities along the Brazilian coast produce a variety of fish types, generating a large amount of waste, including viscera and fish scales, which are already used in several industrial processes. However, these cities still face a large environmental problem, i.e., residue disposal from commercial establishments, e.g., fishmongers, which are often discarded in a disordered and/or unplanned manner in inappropriate places. Within this scenario, the energy utilization of an animal biomass supplied by a fishery in the city of São Luís was investigated, submitting samples to combustion (synthetic air) and pyrolysis (100% N2) processes for the bioenergy generation. Physicochemical properties from fish scales were evaluated by proximate and ultimate analyzes, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and inductively coupled plasma - optical emission spectroscopy (ICP-OES). The thermal behavior of samples was evaluated by thermogravimetry/derivative thermogravimetry (TG/DTG), differential thermal analysis (DTA) and calorimetry (HHV/LHV). It was verified that the fish scales have carbon and oxygen the major elements, and insignificant amounts of sulfur and heavy metals (lead, copper, chromium, lithium, zinc). This material also presented a large amorphous region (89%), in addition to the presence of collagen fibers and hydroxyapatite crystals. The thermal and physicochemical characteristics of this material were evaluated and compare it to other biomasses already in use, predicting its use for the bioenergy generation.

Nickel selenate: a deep and efficient characterization

This work aims to determine the nickel selenate hexahydrate thermal behavior by simultaneous thermogravimetry–differential thermal analysis and differential scanning calorimetry and characterize its thermal intermediates decomposition. Moreover, at 25 °C, this material is a green-colored compound; however, with the temperature increase (until 420 °C), a color change from yellowish green to yellowish orange and finally to yellow was observed. This characteristic is due to the water molecules release, changing the ultraviolet–visible/near-infrared spectroscopy analysis absorption spectra and consequently modifying the crystal structure, as confirmed by X-ray powder diffraction, and resulting in visual changes in photo-DSC. The new data are essential to determine the better conditions to use this material as a precursor in synthesis and also to use it in future applications.