Simultaneous Thermal Analysis Research Articles

Influences of Sulfur-Containing Components on the Key Phases of FeS Spontaneous Combustion Dynamics

ABSTRACT In petroleum storage tanks, sulfur-containing crude oil continues to corrode equipment, generating sulfur corrosion products such as FeS. These products exhibit rapid exothermic reactions upon contact with air, thereby increasing the risk of fires and explosions. Additionally, sulfur monomers precipitated from sulfur or other compounds present in crude oil can adhere to FeS, consequently altering its spontaneous combustion characteristics. To explore the impact of associated sulfur content on the spontaneous combustion characteristics of FeS during its formation, this research synthesized FeS and its sulfur mixtures with sulfur concentrations of 5%, 10%, 15%, and 20%. These mixtures were prepared using a liquid-phase method, which involved the synthesis of self-made active FeS followed by the addition of different sulfur components. Differences in the spontaneous combustion characteristics of the five groups of samples were investigated in stages by simultaneous thermal analysis. The trends of the characteristic parameters of spontaneous combustion of FeS with different percentages of sulfur-containing components were analyzed. Finally, the apparent activation energy values of FeS with FeS and its associated sulfur were calculated by using thermodynamic analysis in the room-temperature spontaneous combustion stage (RT-75℃) and high temperature combustion stage (160–250℃). The findings indicate that the presence of sulfur components enhances the reactivity of FeS, yet reduces its oxygen absorption saturation threshold, thus advancing the oxygen absorption endpoint and facilitating entry into the high-temperature combustion stage. Moreover, FeS and its associated sulfur exhibit prolonged sustained combustion times when the sulfur component percentage is below 10%, favorably influencing the combustion behavior of FeS. As the percentage of sulfur component increases (from 10% to 20%), the combustion duration temperature rises from 60°C to 95°C. Additionally, an increase in the percentage of sulfur component (from 10% to 20%) leads to a higher combustion temperature. The activation energies of the five samples were determined using the Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) kinetic methods. During the room temperature spontaneous combustion stage, the activation energy increases from 65.05 kJ/mol to 112.44 kJ/mol as the percentage of sulfur component rises from 0% to 20%. During the high temperature combustion stage, the activation energy increased from 108.32 kJ/mol to 214.49 kJ/mol with the increase in the percentage of sulfur component. FeS and its associated sulfur necessitate energy to propel the process due to heat absorption from the melting of sulfur monomers. As the reaction progresses into the high temperature stage, the required activation energy escalates accordingly.

Studies on the Thermal Decomposition Course of Nitrogen-Rich Heterocyclic Esters as Potential Drug Candidates and Evaluation of Their Thermal Stability and Properties

Drug candidates must undergo thermal evaluation as early as possible in the preclinical phase of drug development because undesirable changes in their structure and physicochemical properties may result in decreased pharmacological activity or enhanced toxicity. Hence, the detailed evaluation of nitrogen-rich heterocyclic esters as potential drug candidates, i.e., imidazolidinoannelated triazinylformic acid ethyl esters 1–3 (where R1 = 4–CH3 or 4–OCH3 or 4–Cl, and R2 = –COOC2H5) and imidazolidinoannelated triazinylacetic acid methyl esters 4–6 (where R1 = 4–CH3 or 4–OCH3 or 4–Cl, and R2 = –CH2COOCH3)—in terms of their melting points, melting enthalpy values, thermal stabilities, pyrolysis, and oxidative decomposition course—has been carried out, using the simultaneous thermal analysis methods (TG/DTG/DSC) coupled with spectroscopic techniques (FTIR and QMS). It was found that the melting process (documented as one sharp peak related to the solid–liquid phase transition) of the investigated esters proceeded without their thermal decomposition. It was confirmed that the melting points of the tested compounds increased in relation to R1 and R2 as follows: 2 (R1 = 4–OCH3; R2 = –COOC2H5) < 6 (R1 = 4–Cl; R2 = –CH2COOCH3) < 5 (R1 = 4–OCH3; R2 = –CH2COOCH3) < 3 (R1 = 4–Cl; R2 = –COOC2H5) < 1 (R1 = 4–CH3; R2 = –COOC2H5) < 4 (R1 = 4–CH3; R2 = –CH2COOCH3). All polynitrogenated heterocyclic esters proved to be thermally stable up to 250 °C in inert and oxidising conditions, although 1–3 were characterised by higher thermal stability compared to 4–6. The results confirmed that both the pyrolysis and the oxidative decomposition of heterocyclic ethyl formates/methyl acetates with para-substitutions at the phenyl moiety proceed according to the radical mechanism. In inert conditions, the pyrolysis process of the studied molecules occurred with the homolytic breaking of the C–C, C–N, and C–O bonds. This led to the emission of alcohol (ethanol in the case of 1–3 or methanol in the case of 4–6), NH3, HCN, HNCO, aldehydes, CO2, CH4, HCl, aromatics, and H2O. In turn, in the presence of air, cleavage of the C–C, C–N, and C–O bonds connected with some oxidation and combustion processes took place. This led to the emission of the corresponding alcohol depending on the analysed class of heterocyclic esters, NH3, HCN, HNCO, aldehydes, N2, NO/NO2, CO, CO2, HCl, aromatics, and H2O. Additionally, after some biological tests, it was proven that all nitrogen-rich heterocyclic esters—as potential drug candidates—are safe for erythrocytes, and some of them are able to protect red blood cells from oxidative stress-induced damage.

Influences of the Decomposition Atmosphere and Heating Rate on the Pyrolysis Behaviors of Resin Sand

The pouring of sand casting is accompanied by severe heat conduction, and there is an urgent need to investigate the pyrolysis properties of foundry sand. The main purpose of this study was to investigate the pyrolysis behaviors of resin sand, including precoated sand (PCS), hot box sand (HBS), and warm box sand (WBS), at heating rates of 20 °C/min, 30 °C/min, and 40 °C/min in nitrogen and air atmospheres. The mass loss of the resin sand was monitored continuously with a simultaneous thermal analyzer, and the kinetic parameters of the resin sand were calculated based on the Coats–Redfern method and thermal data. The average mass loss of the resin sand during pyrolysis was 3.03%, which was much smaller than that of the other sands. The volatile release characteristic index of resin sand could not be calculated based on this concept. To solve this issue, the term Tstv/mloss was established, and its value was determined. With increasing heating rates from 20 °C/min to 30 °C/min and from 30 °C/min to 40 °C/min, the mass losses of the resin sand increased by 0.79% and 0.64%, respectively, and the volatile release characteristic indices of the resin sand increased by 3.8 × 10−10 and 1.06 × 10−9, respectively. In addition, the mass losses and volatile release characteristic indices of resin sand in an air atmosphere were greater than those in a nitrogen atmosphere. With increasing heating rate, the activation energy of the resin sand decreased in a nitrogen atmosphere. The findings concerning the thermal decomposition behaviors of resin sand provided a theoretical basis for the pouring step of the sand casting process.

Functionalized corn stalk carboxymethyl cellulose and mesoporous silica SBA-15 composite hydrogel-immobilized lipase for the resolution of racemic ibuprofen ethyl ester

ABSTRACT The immobilization of enzymes is an important strategy to improve their stability and reusability. However, it often comes with a trade off of reduced biological activity and catalytic efficiency. In this study, a composite hydrogel based on corn stalk carboxymethyl cellulose, acrylic acid, and mesoporous silica SBA-15 was developed as a support for the immobilization of lipase from Pseudomonas S.P. (PSL). The surface morphology and functional properties of the composite hydrogels were investigated by scanning electron microscopy, Fourier transform infrared, X-ray diffraction and simultaneous thermal analyzer, respectively. The composite hydrogel materials had a large number of mesopores and macropores were present in the wall of the hydrogel sheet. The hydrogel had a network structure that reduced the diffusion resistance of the substrate and improved the accessibility of the enzyme. The immobilized PSL exhibited high enantioselectivity (E value: 88.2) and enzyme activity (316.8 µmol/g/min) in the preparation of (S)-ibuprofen by enzymatic hydrolytic resolution of racemic ibuprofen ethyl ester. This prepared novel composite hydrogel is a promising supporting matrix for the immobilization of enzymes.

Enhancing the Analysis of Eu3+ Photoluminescence in Coordination Compounds in the Solid State by Determining their Refractive Index

This study is focused on determining the refractive index as a crucial parameter for evaluating the intrinsic quantum yield and the ligand sensitisation efficiency in solid‐state trivalent lanthanide coordination compounds. For this, eight trivalent europium complexes with phenyl‐terpyridine ([EuX3(ptpy)(L)], X = Cl– or NO3–, ptpy = 4'‑phenyl‑2,2':6',2''‑terpyridine, L = H2O or other molecules) were examined. Their refractive indices were determined using the Becke lines test by immersing transparent material in a series of media with known refractive indices. Using the set of media presented here, determining crystalline materials' refractive indices from 1.41 to 1.73 with a step of 0.01 is possible. Assessment of the refractive indices of the complexes mentioned above allowed a comprehensive analysis of their photophysical properties in the solid state. Moreover, this method can be extrapolated for other solid‐state materials, offering valuable insights in the broader field of photophysics. In addition to photoluminescence investigations, the compounds presented were characterised by single‐crystal X‐ray diffraction (SCXRD), powder X‐ray diffraction (PXRD), Hirschfeld surface area analysis, UV‑Vis reflectance spectroscopy, hydrolysis sensitivity analysis, and simultaneous thermogravimetry and differential thermal analysis coupled with mass‐spectrometry (STA‐MS).

Effects of WC/TiC addition on the thermodynamic behavior of TiB2-based cermet during sintering process

The heat absorption, weight change and exhaust behavior of TiB2-based cermet powder mixtures with additions of WC, TiC and WC-TiC were analyzed by a simultaneous thermal analyzer coupled with a mass spectrometer (TG/DSC-QMS). Thermodilatometry was used to investigate the densification behavior due to sintering process of cermets. During the sintering process, the order of degassing is: water vapor, CO2 released by the reduction of adsorbed oxygen in the raw material powder, CO and CO2 released by the reduction of surface oxides of Co and Ni powder, WC powder, TiB2 and TiC powder. The addition of WC, TiC and WC-TiC accelerated the reduction of oxides on the surface of Co and Ni powders, and decreased the temperature point of liquid phase formation in TiB2-based cermet. WC and TiC dissolved in liquid CoNi binder and then precipitated on the undissolved TiB2 particles to form a typical core-rim structure during the sintering. This study is expected to lay a solid foundation for the development of high-performance TiB2-based cermets based on TiB2-CoNi, TiB2-WC-CoNi, TiB2-TiC-CoNi and TiB2-WC-TiC-CoNi cermets in the future.

Study on the Properties of Belite Calcium Sulfoaluminate Cement–Ordinary Portland Cement Composite Cementitious System

Due to low early strength and high shrinkage, ordinary Portland cement (OPC) has difficulty meeting the actual needs of modern construction projects, while belite calcium sulfoaluminate cement (BCSA–OPC) composite cement provides a new solution. The mechanical and the drying shrinkage properties of the BCSA–OPC mortar were determined, the hydration heat of the BCSA–OPC was studied, and the pore size distribution of the mortar was investigated. In addition, the hydration products of the BCSA–OPC were analyzed by X-ray diffraction (XRD) and simultaneous thermal analysis (TG-DSC), and the microscopic morphology of the BCSA–OPC mortar was observed by scanning electron microscopy (SEM). The results show that with the increase in BCSA dosage in the BCSA–OPC, compared with OPC, the flexural strengths of the mortar of 50% dosage of BCSA at the hydration age of 1 d, 3 d, 7 d, and 28 d are improved by 33.3%, 36.6%, 23.6%, and 26.8%, and the compressive strengths are improved by 50.8%, 35.7%, 13.4%, and 27.7%. The drying shrinkage and total porosity of the mortar at the hydration age of 28 d are reduced by 117.4% and 21.55%, respectively. It is attributed to the filling effect of a large amount of ettringite (AFt) and intertwined with the fibrous C-S-H gel to form a network. This study will provide a theoretical basis for the application of the BCSA–OPC engineering.

Фотодеструкция полилактида с добавками терпеновых производных фенола и анилина

The article is devoted to the development of new photostabilizers of polylactide, a polymer that is an environmentally friendly alternative to fossil-based polymers. The new photostabilizers are designed to extend the life of products when exposed to ultraviolet radiation and maintain the performance of the polymer when recycled. Photostabilizers 2-isobor-nylphenol and N-para-mentenaniline were obtained while the available natural monoterpene camphene alkylation of phenol or aniline. Irradiation of polylactide samples with a photostabilizer was carried out by radiation with 253,7 nm wavelength for 4 h. The effectiveness of the photostabilizer was evaluated on the basis of IR spectrometric data, as well as by scanning electron microscopy and simultaneous thermal analysis. The introduction of each of the selected stabilizers at the concentration of 0.05% by weight resulted in the protection of ester bonds between the monomer units of the polymer. However, 2-isobornylphenol was more effective. The IR spectra analysis of the irradiated samples revealed a 15% decrease in the absorption intensity of the characteristic bands of the ester groups in the sample with 2-isobornyl-phenol, 46% in the sample with N-para-mentenaniline, and 50% in the sample without stabilizer addition. Thus, the use of 2-isobornylphenol as a photoprotective additive will extend the service life of polylactide plastic products under exposure to aggressive UV-C radiation. The protection of polylactide from UV radiation opens up prospects for expanding the areas of application of polylactide, a polymer synthesized from renewable raw materials.

Thermochemical heat storage performance of Fe-doped MgO/Mg(OH)2: Experimental and DFT investigation

MgO/Mg(OH)2 thermochemical heat storage system can realize large-scale energy storage by repetitive hydration/dehydration reactions to enhance the stability of solar energy utilization. However, slow interconversion and incomplete reactions caused by agglomeration restrict the cyclic heat storage capability of MgO/Mg(OH)2. In this work, a low-cost efficient Fe-doped MgO was prepared by a simple wet-mixing method and its energy released performance and kinetics in MgO/Mg(OH)2 heat storage progress were examined in a twin fixed-bed reactor and a simultaneous thermal analyzer. Additionally, density functional theory calculations were used to examine the impact of Fe on the mechanisms of MgO/Mg(OH)2 heat storage process. The results shows that when the molar ratio of MgO to Fe is 95:5, the energy released density of Fe-doped MgO is about 400 % higher than that of MgO after 10 heat storage cycles. In preparation process, the existence of Fe leads to the generation of MgFe2O4, which forms layered microstructure with the high specific surface area and pore volume and mitigates agglomeration behavior of MgO. It improves the cyclic stability of MgO and reduces the dehydration temperature of Mg(OH)2, and simultaneously the activation energy of the dehydration stage is reduced by 33.2 %. Fe enhances the interaction of H2O with the MgO surface and promotes the dissociation of H2O on Mg(OH)2 surface. Combined with economic analysis, Fe-doped MgO is a suitable material for MgO/Mg(OH)2 heat storage cycles.

Fluconazole Microemulsions: Preparation, Statistical Optimization by Two-Level Factorial Design, and Physicochemical Evaluation

Background:: Candida albicans is the yeast that causes the fungal infection known as candidiasis. One of the standard methods for treating candida is the application of fluconazole. The low solubility of fluconazole in aqueous media is a big problem in the use of this agent. Novel drug delivery systems, such as microemulsions, could be applied to solve this problem. The main aim of this study was to perform statistical optimization of the formulation and physicochemical characterization of fluconazole microemulsion. Methods:: Optimization of the microemulsion formulation was done by using experimental design software, and then fluconazole was loaded onto the best formulation at a concentration of 1 % w/w. The physiochemistry of the microemulsion formulation was assessed by pH measurement, rheology measurement, simultaneous thermal analysis, and Scanning Electron Microscopy (SEM). Results:: The two-level fractional factorial design application demonstrated the optimum formulation to consist of surfactant, co-surfactant, oil content, and water, comprising 58%, 27%, 10%, and 5% of the formulation, respectively. Desirable thermal mass was observed up to 150°C. The formulation was a non-Newtonian shear-thinning liquid in terms of viscosity, with a reported pH between 6.5-7. Conclusion:: Considerably stable, high-quality microemulsion formulations containing fluconazole are presented, which are applicable for antifungal skin candidiasis treatment in clinical trials.

Experimental and modeling study of the effect of confinement on the thermal decomposition of organic materials

Simultaneous Thermal Analysis is widely used to study thermal decomposition of a variety of organic materials, and the choice of experimental conditions is very important to obtain reliable mass loss and heat flow curves. In this work we investigate the effect of confinement on the thermal decomposition of organic materials. As an example, we explore high-density polyethylene (HDPE) and one of its pyrolysis products, namely eicosane (C20H42), through experiments and modeling in open crucibles and crucibles closed with a pierced lid. A new model is developed for evaporation and sublimation from open and pinhole thermal-analysis pans. It considers the kinetic resistance of evaporation at the liquid-vapor interface, inhibition of evaporation by buildup of vapor inside the pan, thermal expansion of vapor inside the pan, and diffusion of vapor from the pan. The model is validated using simultaneous heat-flow and mass-loss measurements of n-eicosane evaporation for various pinhole sizes, down to 50 µm. The importance of product evaporation inhibition for measuring polymer decomposition was demonstrated using HDPE. This study sheds light on the effect of confinement on the mass loss rate of organic materials.

Study on a novel Si3N4-based composite with the incorporation of N-GQDs produced from nano-lignin

In order to enhance the mechanical properties of ceramic materials and realize the high value utilization of lignin, the nano-lignin precursor was added into the silicon nitride matrix as the second phase to obtain a novel ceramic composite material with excellent mechanical performance in this study. During the preparation, the nano-lignin was transformed into nitrogen-doped graphene quantum dots(N-GQDs) in the ceramic matrix by the pyrolysis-hot pressing sintering coupling process. Aiming to reveal the pyrolysis conversion process of lignin, the segmented products at the different temperature gradient were prepared, and their phase composition and microstructure were deeply analyzed by various test methods. In addition, the continuous pyrolysis process of nano-lignin was further studied by simultaneous thermal analyzer. The results showed that, nano-lignin was transformed into solid products (amorphous carbon) in the temperature range of room temperature to 800 °C and produced a large number of volatiles. Subsequently, in the temperature range of 800∼1400 °C, part of amorphous carbon began to transform into N-GQDs, and part of α-Si3N4 also began to transform into β-Si3N4. When the temperature rose to the temperature of 1700 °C, all amorphous carbon was transformed into N-GQDs through carbon structure rearrangement and nitrogen doping, and meanwhile the most of α-Si3N4 was transformed into β-Si3N4. At the final stage, β-Si3N4 columnar grains were covered by an overlayer composed of N-GQDs, and a novel ceramic composite with a special “core-shell” microstructure was obtained and exhibited excellent mechanical performance. This study presents a promising approach for the preparation of high-performance ceramic materials, and can also intrigue great interests in lignin graphitization and lignin-derived carbon materials.

Mesoporous silica nanoparticles decorated with C3N4 framework as a novel electrocatalyst for the design of a selective clonazepam sensor

In this study, a new chemical modifier based on copper nitrate hydroxide-containing mesoporous silica decorated with a C3N4 framework (MSN/C3N4/CNH) was developed to design a modified sensor for the determination of clonazepam (CZP). The resulting composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), simultaneous thermal analysis (STA), Brunauer-Emmett-Teller (BET) and Barrett Joyner–Halenda (BJH) analyses. The fabricated electrochemical sensor which was designed with a new modified glassy carbon electrode (GCE) for CZP analysis, exhibits outstanding electrocatalytic activities toward the reduction of CZP. The results showed that significant sensitivity compared to existing methods improved with an excellent detection limit of 2.50 nmol L−1 for the CZP detection, and the modified electrode has high activity toward the oxidation and reduction of CZP, with an oxidation peak around 0.32 V, and a lower reduction peak around −0.78 V; at pH = 7.0. The effect of experimental and instrumental factors on the electrochemical sensor response was examined, and the cyclic voltammetric results confirmed the 4H+/4e− process in the electrochemical studies. Moreover, in differential pulse voltammetry, the reduction peak current was proportional toward the CZP concentration from 0.82 to 76.90 μmol L−1, at optimum conditions. The modified electrode showed good reproducibility, and repeatability with relative standard deviation values of 2.7% and 1.2%, respectively. The proposed method can be applied as a simple, selective, and precise method to determine CZP drug in real samples, with satisfactory results.

Bacterial Nanocellulose Hydrogel for the Green Cleaning of Copper Stains from Marble.

Cultural heritage stone materials frequently experience significant discoloration induced by copper corrosion products, especially calcareous stones associated with bronze or copper statues and architectural elements. This alteration originates from the corrosion of unprotected copper, resulting in the formation of various Cu minerals and the migration of soluble ions to adjacent stone materials. Traditional cleaning methods involve mechanical, chemical, and laser techniques, which are generally time-consuming, costly, not ecological, or can possibly damage original materials. The loading of highly effective chelating agents, such as ethylenediaminetetraacetic acid (EDTA), into hydrogels has recently been exploited. However, the preference for synthetic hydrogels has been prominent until now, although they lack renewability and biodegradability and require high costs. This study explores for the first time the potential to clean copper corrosion with bacterial nanocellulose (BC) loaded with EDTA as a biologically based, sustainable, and biodegradable hydrogel. The BC hydrogel was characterised by field emission-scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), simultaneous thermal analysis (TG-DSC), and tensile testing. It revealed a nano-fibrous structure with high crystallinity and purity and mechanical properties suitable for cultural heritage applications. The EDTA-loaded hydrogel effectively removed copper stains from marble after 120 min of application. Micro-Raman and colorimetric analyses assessed the cleaning efficacy. The study introduces bacterial nanocellulose as a green and effective alternative for heritage conservation, aligning with sustainable methodologies in stone conservation.

Feroxyhyte - from synthesis and characterization to application.

Feroxyhyte (δ-FeOOH) was synthesized and characterized using X-ray diffractometry (XRD), simultaneous thermal analysis (STA), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), and low-temperature nitrogen adsorption-desorption measurements. Its potential application as adsorbent of an anionic and cationic dyes such as C.I. Acid Violet 1 (AV1) and C.I. Basic Blue 3 (BB3) was investigated by determining the adsorption capacities based on the Langmuir (36.6 mg/g for AV1 and 187 mg/g for BB3), Freundlich and Dubinin-Radushkevich isotherm models. Adsorption of AV1 and BB3 by δ-FeOOH drops with the presence of additives such as cationic and anionic surfactants (CTAB, SDS) and ionic polymers (PAA, PEI). The surface and electrokinetic properties of examined suspensions were also described. They include determination of the solid surface charge density and the zeta potential, as well as values of point of zero charge and isoelectric point of feroxyhyte particles without and with adsorbed layers of organic substances. Their analysis made possible to propose the most probable structure of electrical double layer formed at the iron mineral/aqueous solution interface.

The Influence of Alkaline Pretreatment of Waste Nutshell for Use in Particulate Biocomposites

The aim of this work was to determine how different types of alkaline pretreatment influence the properties of waste almond and hazelnut nutshell, as well as their compatibility with model inorganic geopolymer matrixes for the formation of biocomposites with potential use in civil engineering. For alkaline pretreatment, 3, 6 and 9% NaOH water solutions and milk of lime were used under different temperature and time conditions. The rise in the crystallinity index was confirmed by X-ray powder diffraction analysis, while the corroboration of the removal of amorphous and undesirable components was demonstrated through Fourier-transform infrared spectroscopy. Furthermore, the effectiveness of the pretreatments was confirmed via simultaneous differential thermal and thermogravimetric analysis, and the positive change in the morphology of the surface of the waste nutshell (WN) and the deposition of the desired phases was established using scanning electron microscopy. Surface free energy and adhesion parameters were calculated using the Owens, Wendt, Rabel and Kaelble method for WN as fillers and geopolymers as model novel inorganic binders. This research indicates that the 6% NaOH treatment is the optimal pretreatment process for preparing WN as the filler in combination with potassium and metakaolin geopolymer that has been cured at room temperature.

Carboxymethyl Scleroglucan Synthesized via O-Alkylation Reaction with Different Degrees of Substitution: Rheology and Thermal Stability.

This paper presents the methodology for synthesizing and characterizing two carboxymethyl EOR-grade Scleroglucans (CMS-A and CMS-B). An O-Alkylation reaction was used to insert a hydrophilic group (monochloroacetic acid-MCAA) into the biopolymer's anhydroglucose subunits (AGUs). The effect of the degree of the carboxymethyl substitution on the rheology and thermal stability of the Scleroglucan (SG) was also evaluated. Simultaneous thermal analysis (STA/TGA-DSC), differential scanning calorimetry (DSC), X-ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning Electron Microscopy, and Energy Dispersive Spectroscopy (SEM/EDS) were employed to characterize both CMS products. FTIR analysis revealed characteristic peaks corresponding to the carboxymethyl functional groups, confirming the modification. Also, SEM analysis provided insights into the structural changes in the polysaccharide after the O-Alkylation reaction. TGA results showed that the carboxymethylation of SG lowered its dehydroxylation temperature but increased its thermal stability above 300 °C. The CMS products and SG exhibited a pseudoplastic behavior; however, lower shear viscosities and relaxation times were observed for the CMS products due to the breakage of the SG triple helix for the chemical modification. Despite the viscosity results, the modified Scleroglucans are promising candidates for developing new engineering materials for EOR processes.

Application of Simultaneous and Coupled Thermal Analysis Techniques in Studies on the Melting Process, Course of Pyrolysis and Oxidative Decomposition of Fused Triazinylacetohydrazides.

The effect of the structure of promising antioxidant agents with prospective medical use, i.e., unsubstituted and para-substituted annelated triazinylacetic acid hydrazides, on their melting points, thermal stabilities, pyrolysis and oxidative decomposition stages and the type of volatiles emitted under heating with the use of DSC and TG/DTG/FTIR/QMS methods was evaluated and discussed. The melting point of the investigated compounds increased with an enhanced number of electrons (directly correlated with their molecular weight). Melting enthalpy values were determined and presented for all the studied compounds. The pyrolysis and oxidative decomposition processes of the analysed molecules consisted of several poorly separated stages, which indicated a multi-step course of the decomposition reactions. It was found that the thermal stability of the tested compounds depended on the type of substituent at the para position of the phenyl moiety or its absence. In both atmospheres used (air and helium), the thermal stability increased in relation to R as follows: -CH3 ≤ -OCH3 < -H < -OC2H5. In an inert atmosphere, it was higher by approx. 8-18 °C than in an oxidative atmosphere. The pyrolysis was connected with the emission of NH3, HCN, HNCO, HCONH2, HCHO, CO2, CO and H2O in the case of all the tested compounds, regardless of the substituent attached. In the case of the derivative containing the para-CH3 group, para-toluidine was an additional emitted aromatic product. In turn, emissions of aniline and alcohol (methanol or ethanol) for compounds with the para-OCH3 and para-OC2H5 groups, respectively, were confirmed. In oxidative conditions, the release of NH3, NO, HCN, HNCO, HCONH2, CO2, H2O and cyanogen (for all the compounds) and para-toluidine (for the para-CH3 derivative), aniline (for para-OCH3, para-OC2H5 and unsubstituted derivatives) and acetaldehyde (for the para-OC2H5 derivative) were clearly observed. No alcohol emissions were recorded for either compound containing the para-OCH3- or para-OC2H5-substitututed phenyl ring. These results confirmed that the pyrolysis and oxidative decomposition of the investigated annelated triazinylacetohydrazides occurred according to the radical mechanism. Moreover, in the presence of oxygen, the reactions of volatiles and residues with oxygen (oxidation) and the combustion process additionally proceeded.

Exploring the potential of drill cuttings for reservoir characterization: A case study from the Volga-Ural basin, Russia

The research objectives are to assess the possibility of using drill cutting analysis to obtain information about the mineralogical and geochemical properties of the reservoir rocks. Drill cutting samples were collected from a vertical well that penetrated the Domanik sediments (Semiluksk Formation) in one of the oil fields in the Volga-Ural petroleum province. Thin sections from drill cuttings were examined using an optical polarizing microscope (Axio Imager A2). X-ray diffraction (XRD) analyses were performed using a Brucker D2 Phaser X-ray powder diffractometer. Thermophysical properties were studied using an STA 449 F3 Jupiter instrument. The pyrolytic studies were performed using the Rock-Eval method. Visual inspection showed that the studied sediments are alternations of carbonates and siliceous-carbonate rocks. Thin section examinations revealed that the carbonates are mainly limestone (mudstone and wackestone) and are characterized by a dense texture and up to 30 % organic residues. The siliceous-carbonate rocks are dominated by siliceous mudstones and are characterized by dark colours, layered structure, and an enrichment in organic matter. XRD analyses showed that the carbonate rocks are mainly composed of calcite, dolomite, quartz, feldspar, and mica, which are minor components. The siliceous-carbonate rocks are dominated by quartz, followed by calcite, although they also contain feldspars, mica, dolomite, and pyrite as impurities. According to the simultaneous thermal analysis, the average total hydrocarbon in the carbonate and siliceous-carbonate rocks is 13.6 % (for the core samples) and 11.5 % (for the drill cutting samples). The content of heavy hydrocarbons in the rocks is higher than the content of light hydrocarbons, indicating the immature nature of organic matter. Kerogen is found sporadically in siliceous-carbonate rocks. According to the pyrolytic studies, average S1 is 4.4 mg/g and average S2 is 19.8 mg/g (for the core samples); average S1 is 2.1 mg/g and average S2 is 17.8 mg/g (for the drill cutting samples), which indicated that the studied sediments have very good to excellent generation potential. The average Tmax of 425.7 °C (for the drill cutting samples) and 427.9 °C (for the core samples) indicate immature organic matter that generated only heavy oils. Comparing the results of the analysed drill cutting samples with the results of the analysed core analysis from the same reservoir interval in the neighbouring wells showed a good correlation, which proves that this technique is a valid tool that provides an alternative, cost-effective method to determine the rock's characteristics from drill cuttings.

Chemical synthesis, characterization and spark plasma sintering of cu and Cu/TiO2 composite powders

Pure Cu and Cu/TiO2 composite powders with 10 and %20 wt% TiO2 were synthesized via chemical precipitation method. The initial precipitates were obtained by adding ammonium hydrogen carbonate to copper nitrate and copper nitrate/TiO2 comtaining solutions drop by drop. The precipitates were calcined at 450?C according to simultaneous thermal analysis results in air. The calcined powders were reduced in hydrogen atmosphere at 500?C. The reduced powders were spark plasma sintered at 730?C. The microstructural evaluations of the sintered samples showed a nearly dense microstructure with a fine dispersion of TiO2 within the Copper matrix. The hardness value of the Cu/TiO2 composites was 90 HV higher than that of pure copper. The wear test results showed that by increasing the TiO2 content, the average coefficient of friction (COF) increased so that the lowest COF was obtained for the monolithic Cu sample. However, the wear rate of Cu/10wt% TiO2 composites was the lowest among the sintered powders which was due to the highest hardness of this group of samples.