Thermal Analysis Research Articles

An Experimental Study on Deuterium Production from Titanium Hydride Powders Subjected to Thermal Cycles

An extensive multi-year experimental study was conducted to investigate the potential production of deuterium from titanium hydride TiHx powders subjected to specific thermal cycles. Mass spectrometry was performed, focusing on the variation in signal intensities at m/z = 2, 3, 4, 18, 19, 20, and 21, corresponding to fragments primarily involving deuterium, during the degassing of titanium hydride powders as the sample temperature was raised from room temperature to approximately 1100 °C. The results reveal an anomaly in the deuterium-to-hydrogen ratios, with the analysis indicating an increase in deuterium concentration by a factor of approximately 280 compared to its natural concentration on Earth. Three independent methods confirmed the excess deuterium. Simultaneously, flow calorimetry was performed during the degassing process, which did not show any measurable excess heat produced in the configuration used. This study was motivated by our novel theoretical predictions, based on the standard electroweak theory with gauge symmetry, suggesting the generation of slow neutrons within metal hydrides when exposed to coherent excitations. Our findings align with direct measurements of neutron emission by TiHx powders under cavitation in liquid water, as recently published by Fomitchev-Zamilov.

Exploring the Mechanical and Thermal Impact of Natural Fillers on Thermoplastic Polyurethane and Styrene–Butadiene Rubber Footwear Sole Materials

The increasing concern for sustainability in the footwear industry has spurred the exploration of eco-friendly alternatives for materials commonly used in sole manufacturing. This study examined the effect of incorporating rice straw and cellulose as fillers into soles made from either styrene–butadiene rubber (SBR) or thermoplastic polyurethane (TPU). Both fillers were used as a substitute in mass percentages ranging from 5 to 20% in the original SBR and TPU formulas, and their impact on mechanical properties such as abrasion and tear resistance, as well as thermal properties, was thoroughly evaluated. The results demonstrated that the inclusion of fillers affects the overall performance of the soles, with the optimal balance of mechanical and thermal properties observed at a 10% filler content. At this level, improvements in durability were achieved without significantly compromising flexibility or abrasion resistance. Thermal analysis revealed increased thermal stability at moderate filler contents. This research not only offers a sustainable alternative to traditional materials but also enhances sole performance by improving the composition. Furthermore, this study paves the way for future research on the feasibility of incorporating eco-friendly materials into other consumer product applications, highlighting a commitment to innovation and sustainability in product design.

Synthesis and Characterization of Cobalt–Organic Framework as an Electrocatalyst for Water Splitting Application

ABSTRACTClimate change is seen as a crucial environmental dilemma that humanity will confront in the upcoming decade. For this purpose, the solvothermal‐assisted technique is used to create metal–organic frameworks (MOFs), which are porous materials characterized by strong connections between organic ligands and metal ions. The MOF discussed here contains cobalt as the metal node and a linker derived from 2‐aminobenzoic acid and terephthalaldehyde. The prepared powder underwent analysis using various techniques including Fourier‐transform infrared spectroscopy (FT‐IR), powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area measurement, and thermal analysis. BET analysis revealed a surface area of 1587.06 m2/g, a total pore volume of 0.86394 cc/g, and an average pore size of 1.088 nm. The RGO@Co‐MOF prepared was utilized to evaluate water splitting efficiency, demonstrating favorable catalytic activity like most reported modified MOF catalysts under low current density conditions of 10 mA/cm2.

EVALUATION OF THE ANTIOXIDATIVE EFFICACY OF FULLERENE SOOT DOPED BY C60/C70 (85/15) FOR LOW-DENSITY/HIGH PRESSURE POLYETHYLENE NANOCOMPOSITES

Fullerenes (C60-70) although effective stabilizers-antioxidants for polymeric materials they have not yet found widespread practical application because of their high cost. As such, polymer manufacturers prefer to use classical stabilizers. In order to try to overcome this situation for some useful applications here the evaluation of relatively cheap fullerene soot (FS) doped additionally by C60/C70(85/15) is undertaken. Solution kinetic studies on the inhibition of model cumene oxidation combined with the thermal and mechanical analysis of the FS+C60/C70 integrated in a low-density/high pressure polyethylene (LDPE) matrix demonstrates the obvious advantage of a such an approach. The kinetic analysis made on the model reaction of initiated oxidation of cumene showed that the antioxidant activity of samples of fullerene carbon black doped with fullerenes C60-70 exhibits inhibition rate constants with high enough values comparable to those of strong industrial antioxidants such as Irganox 1010/1076. The additional portions of C60-70 fullerenes slightly increase the commercial cost of the FS itself, while the higher efficiency of the modified fullerene samples shown by thermal and mechanical analysis prevails more and allows us to recommend them for the industrial use at a measured optimal concentration of 1%w/w in the polymer

Self-sufficient power plant prototype composed by cascaded disruptive power units doing work by isothermal contraction and expansion

This research work aims at the design and development of a disruptive prototype for a Self-sufficient power plant (SSPP) prototype composed by cascaded disruptive power units (PUs) doing work by isothermal contraction-expansion processes. The innovative design integrates thermo-hydraulic actuators enabled to drive hydraulic pumps connected to a hydraulic motor-generator. The prototype's cascaded PUs operates on a double closed processes-based isochoric-isothermal-isochoric-isothermal (VTVT) thermal cycle, enabled to do useful work by contraction and expansion of a thermal working fluid (TWF), which is notable for its high specific work output and high thermal efficiency. This is due to a disruptive cascaded heat recovering technique associated to a heat upgrading strategy. Among the most relevant Key Features are its self-sufficient operation modes that challenge traditional limitations of second-kind perpetual motion machines (PMMs) The expected capabilities on the basis of the consistency of empirical analysis are summarized as: - Design based on the optimal number of cascaded power units, - Efficient generation of useful mechanical work through expansion and contraction of the TWF, - High specific useful work (kJ/kg of TWF), such as helium, - Low ratio of actuator volume and weight to specific work. Preliminary tentative validation: The prototype design model was validated through case studies using air and helium as real TWFs. Empirical results demonstrate the SSPP's exceptional performance under certain conditional restrictions. - The optimal SSPP completed with nine cascaded PUs each operating on a double-VTVT cycle per PU. - Helium: RIT value of 0.9 and 9 PUs coupled in cascade to give an SSI of 156.72and a SSEP yield of 922.23 kJ/kg.cy. - Air: RIT value of 0.9 and 9 PUs coupled in a shell to give an SSI of 27.41 and a SSEP production of 37.67 kJ/kg.cy. These findings highlight the prototype's potential to significantly advance energy production efficiency and self-sufficiency in power generation systems.

Effects of Al Substitution for Fe in Na₅FeSi₄O₁₂ (5.1.8) Glasses: Structure and Crystallization

In this study, the effects of substituting Al for Fe in 5Na2O∙(Al2O3)x∙(Fe2O3)1-x∙8SiO2 glass, x=0 to 1, and Na5AlxFe1-xSi4O12 (5.1.8) crystal, were investigated using thermal analysis, Fe K-edge X-ray absorption, X-ray diffraction, Raman spectroscopy, and Electron Probe Microanalysis. In both glass and crystallized glass, nearly all the Fe was tetrahedrally coordinated Fe3+, as expected from the high concentration of Na2O. The substitution of Al for Fe in the glasses caused the glass transition temperature to increase as polymerization increased, as evidenced by Raman, likely due to both field strength differences of Al vs Fe and a small amount of Fe2+ network modifier present with Fe. After heat treatment at 700 °C for 24 hours, the glasses had crystallized, forming Na2SiO3 and NaAlSiO4 in compositions with high Al concentrations and the 5.1.8 crystal in compositions with high Fe concentrations. Through electron microprobe, it was determined that <0.04 formula unit Al incorporated into the 5.1.8 crystal, i.e. Na5Fe0.96Al0.04Si4O12. The 5.1.8 crystal only formed when Fe concentration was higher than Al in the starting glass.

Ferroelectric, Switchable Dielectric and Nonlinear Optical Properties in Inorganic-Organic Lead-Free 1D Hybrids Based on Bi(III) and Azetidine: (C3NH8)2[BiCl5], (C3NH8)2[BiBr5

This study investigates lead-free organic-inorganic hybrids (C3NH8)2[BiCl5] (ABC) and (C3NH8)2[BiBr5] (ABB), focusing on their structural, dielectric, ferroelectric, and optical properties. Both compounds exhibit paraelectric (I) to ferroelectric (II) phase transitions (PTs) at 230/233 K and 228/229 K, respectively, transitioning from orthorhombic (Pnma) to monoclinic (P21) phases, with distorted [BiX6]3- octahedra forming 1D chains. Quasielastic neutron scattering and solid-state 1H NMR studies reveal the localized motion of azetidinium cations. Dielectric measurements of ABC and ABB show step-like permittivity changes by 11-12 units post-transition I → II, demonstrating reversible switching behavior. Absorption studies reveal band gaps of 3.24 eV for ABC and 2.76 eV for ABB, classifying them as insulators. Luminescence spectra at 77K display 578 nm (ABC) and 708 nm (ABB) emissions, attributed to 3P1,0 → 1S0 transitions. Both compounds demonstrate stable second harmonic generation (SHG) switching of the on-off type. The switching performance is evaluated over multiple thermal cycles using the treq metric, which decreases with increasing temperature change rate and indicates that ABB's SHG switching is approximately 30% faster than that of ABC.

A compact X-ray source via fast microparticle streams.

The spatiotemporal resolution of diagnostic X-ray images is limited by the erosion and rupture of conventional stationary and rotating anodes of X-ray tubes from extreme density of input power and thermal cycling of the anode material. Conversely, detector technology has developed rapidly. Finer detector pixels demand improved output from brilliant keV-type X-ray sources with smaller X-ray focal spots than today and would be available to improve the efficacy of medical imaging. In addition, novel cancer therapy demands for greatly improved output from X-ray sources. However, since its advent in 1929, the technology of high-output compact X-ray tubes has relied upon focused electrons hitting a spinning rigid rotating anode; a technology that, despite of substantial investment in material technology, has become the primary bottleneck of further improvement. In the current study, an alternative target concept employing a stream of fast discrete metallic microparticles that intersect with the electron beam is explored by simulations that cover the most critical uncertainties. The concept is expected to have far-reaching impact in diagnostic imaging, radiation cancer therapy and non-destructive testing. We outline technical implementations that may become the basis of future X-ray source developments based on the suggested paradigm shift.

Influence of Different Cements on Bonding Efficiency Between Implant Abutment and Standard Restoration.

This study aimed to investigate the efficiency of different cements for luting implant restorations. Standard restorations were bonded with different cements, including a zincoxide-based temporary cement (ZOE), a resin-modified glass ionomer cement (GIC) and a resin-based, eugenol-free cement (RBEFC). The restorations were stored under moist conditions and were subsequently subjected to thermal cycling and mechanical loading (TCML). Retention forces were determined with an axial tensile test and removabilty of the restorations was analyzed with a pneumatic crown remover. GIC provided significantly higher retention forces than RBEFC, which provided significantly higher values than ZOE. After storage, retention forces were significantly higher than after TCML. With regard to removability, no significant differences were identified between ZOE and RBEFC, but a significantly higher number of applications was required to remove restorations luted with RBEFC. All cements provided sufficient retention forces, yet removal of restoration might be more demanding if luted with RBEFC.

Thermoanalytical and Kinetic Studies for the Thermal Stability of Emerging Pharmaceutical Pollutants Under Different Heating Rates

Emerging pharmaceutical pollutants like ciprofloxacin (CIP) and ibuprofen (IBU) are frequently detected in aquatic environments, posing risks to ecosystems and human health. Since pollutants rarely exist alone in the environment, understanding the thermal stability and degradation kinetics of these compounds, especially in mixtures, is crucial for developing effective removal strategies. This study therefore investigates the thermal stability and degradation kinetics of CIP and IBU, under different heating rates. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were employed to examine the thermal behavior of these compounds individually and in mixture (CIP + IBU) at heating rates of 10, 20, and 30 °C/min. The kinetics of thermal degradation were analyzed using both model-fitting (Coats–Redfern (CR)) and model-free (Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Friedman (FR)) methods. The results showed distinct degradation patterns, with CIP decomposing between 280 and 550 °C and IBU between 152 and 350 °C, while the mixture exhibited multistep decomposition in the 157–500 °C range. The CR model indicated first-order kinetics as a better fit for the degradation (except for IBU). Furthermore, CIP exhibits higher thermal stability and activation energy compared to IBU, with the KAS model yielding activation energies of 58.09 kJ/mol for CIP, 11.37 kJ/mol for IBU, and 41.09 kJ/mol for CIP + IBU mixture. The CIP + IBU mixture generally showed intermediate thermal properties, suggesting synergistic and antagonistic interactions between the compounds. Thermodynamic parameters (ΔH°, ΔG°, ΔS°) were calculated, revealing non-spontaneous, endothermic processes for all samples (except in the FWO method) with a decrease in molecular disorder and positive ΔG° values across all models and heating rates. The study found that higher heating rates led to less thermodynamically favorable conditions for degradation. These findings provide important information concerning the thermal behavior of these pharmaceutical pollutants, which can inform strategies for their removal from the environment and the development of more effective waste-treatment processes.

Thermal and Luminescent Properties of Multi-Ligand Complexes of Europium(III) with Pyrazine-2-carboxylic Acid

Eu(III) compounds with pyrazine-2-carboxylic acid and nitrogen- and phosphorus-containing neutral ligands were synthesized. Using the methods of chemical elemental and thermal analysis and IR spectroscopy, the composition of the complexes and the method of coordination of carboxylate ions were established. The most thermally stable compounds have been identified. The luminescent characteristics of complex compounds have been studied. It was found that the maximum luminescence intensity is characteristic of europium(III) pyrazinate with triphenylphosphine oxide. The morphological structure and dispersion of the complexes were determined.

A Perspective on the Use of Hydroxyapatites to Improve the Dissolution Behavior of Poorly Water-Soluble Piretanide

Background/Objectives: Interest in drug delivery systems (DDS) based on inorganic substrates has increased in parallel with the increase in the number of poorly water-soluble drugs. Hydroxyapatite is one of the ideal matrices for DDS due to its biocompatibility, low cost, and ease of preparation. Methods: We propose two doped hydroxyapatites, one with Ba on Ca sites another with Si on P sites, with the aim of improving the dissolution rate of piretanide, a diuretic, poorly water-soluble drug. The hybrids were characterized by different physical–chemical techniques, and their formation was demonstrated by infrared spectroscopy, thermal analysis, and electron microanalysis, as well as by comparing the results with those obtained on physical mixtures of HAPs and properly prepared piretanide. Results: Both the hybrids improved the piretanide dissolution rate compared with the physical mixtures and the drug alone. The dose was completely solubilized from the Si-doped hybrid in about 5 min in the three fluids considered. This remarkable improvement can be explained by an increase in the wettability and solubility of the drug loaded in the drug-carrier systems. Conclusions: Different experimental techniques, in particular spectroscopy and electronic microanalysis, proved the successful loading of piretanide onto doped HAP. Pharmaceutical measurements demonstrated rapid drug release in different fluids simulating gastrointestinal conditions after oral administration. These hybrid systems could be a very promising platform for drug delivery.

Development and In Vitro Characterization of Azadirachta Indica Gum Grafted Polyacrylamide Based pH-Sensitive Hydrogels to Improve the Bioavailability of Lansoprazole.

The present study intended to develop a pH-responsive hydrogel based on Neem gum (Ng) to improve Lansoprazole (LSP) oral bioavailability. Azadirachta Indica seed extract was used to obtain Ng. pH-responsive hydrogel formulations (F1-F9) were prepared using different Ng ratios, Acrylamide (AAm), and methylene-bis-acrylamide (MBA). The formulated hydrogels were characterized through FTIR, thermal analysis, swelling ratio, SEM, sol-gel ratios, In-Vitro drug release, and cytotoxicity analysis. Azadirachta Indica was extracted to produce a powder containing 21.5 % Ng. Prepared hydrogels showed maximum swelling at pH 7.4, whereas the swelling at an acidic pH was insignificant. LSP-loaded hydrogel demonstrated a regulated release of LSP for up to 24 h and indicated a Super Case II transport release mechanism. During the cytotoxic evaluation, the delivery system showed minimal cytotoxicity towards normal cells, while percent cytotoxicity was carried out for a longer duration (up to 96 h). The present study revealed Azadirachta indica gum-based pH-responsive hydrogel as a promising technique for precisely delivering LSP.

Comparative Analysis of Modern 3D-Printed Hybrid Resin-Ceramic Materials for Indirect Restorations: An In Vitro Study

The study investigated the impact of aging on surface roughness, color stability, and biocompatibility of hybrid resin-ceramic materials. A total of 225 specimens were produced from three three-dimensional (3D)-printed (HarzLabs Dental Sand Pro (HL), BEGO VarseoSmile Crown plus (BV), Voco V-Print c&b temp (VV)) and one milled material (Voco Grandio Blocs (VG)). Specimens were grouped into untreated, polished, and glazed surfaces. 5000 thermal cycles simulated aging. Surface roughness and color stability were analyzed, and surface topography was observed using scanning electron microscopy (SEM). Biocompatibility was evaluated with L929 cells. Surface roughness differed significantly between untreated and other groups, with no changes before and after artificial aging. Untreated milled samples were significantly smoother than 3D-printed ones. SEM analysis revealed roughest surfaces in untreated 3D-printed specimens. Polished and glazed specimens were smoother than untreated ones. Color values showed significant differences between untreated and treated/aged groups. No material showed cytotoxicity. In summary, untreated VG was smoother than 3D-printed materials, but polishing and glazing reduced roughness to levels comparable to VG. Surface treatments induced color changes, with glazing causing more changes than polishing. Aging affected color stability and biocompatibility but not surface roughness. All materials showed acceptable color changes and good biocompatibility.

An Investigation on the High-Temperature Stability and Tribological Properties of Impregnated Graphite

Impregnated graphite is a common material for friction pairs in aeroengine seals, especially at high temperatures. For the convenience of the application of graphite materials in aeroengines, an SRV-4 tribometer and a synchronous thermal analyzer are employed to study the tribological properties and thermal stability of pure, resin-impregnated, metal-impregnated, and phosphate-impregnated graphite against stainless steel from room temperature to 500 °C. The results indicate that impregnations can improve the wear resistance and thermal stability of graphite at high temperatures. Compared with other impregnated graphite materials, the resin-impregnated graphite shows a good friction coefficient and poor wear rate and thermal stability over 300 °C, due to the degradation and oxidation of the resin-and-graphite matrix. The metal- and phosphate-impregnated graphite materials exhibit excellent wear resistance and thermal stability under 500 °C as a result of the protection of the impregnations, while the average friction coefficient of the metal-impregnated graphite is much greater than the phosphate-impregnated graphite, and even reaches 2.14-fold at 300 °C. The wear rates for the graphite impregnated with resin, metal, and phosphate are 235 × 10−7, 7 × 10−7, and 16 × 10−7 mm3N−1m−1 at 500 °C, respectively. Considering all aspects, the phosphate-impregnated graphite exhibits excellent tribological properties and thermal stability.

Study of the residual stress distribution in SiCp/Al composites under thermal cycling conditions

In this study, a three-dimensional random representative volume element model was constructed using the finite element method combined with Python script to investigate the residual stress distribution in SiCp/Al composites with varying volume fractions, particle shapes, and particle size under thermal cycling conditions. The model has two different particle morphologies: spheres and irregular polygons. The results show that the irregular polygonal SiC particles exhibit higher residual stresses than spherical particles before and after thermal cycling due to their complex load transfer pathways and higher stress concentration at particle corners, which makes them more consistent with the characterization of SiCp/Al composites under practical application conditions. As the volume fraction of SiC particles increases, the particle spacing decreases, hindering the release of thermal stresses through plastic deformation. Notably, the relief rate of residual stress reached 53% in the 12 vol% SiCp/Al composites, with the stress decreasing from 698 MPa to 328 MPa after 50 thermal cycles. In contrast, the reduction rate for 18 vol% composites is only 13% after thermal cycling. Furthermore, compared to larger particles (7.3 µm, 8.9 µm), the smaller particles (4.3 µm, 5.9 µm) exhibit a more uniform stress distribution and lower thermal stresses before and after thermal cycling. Consequently, our work provides a significant theoretical basis for the design and application of SiCp/Al composites, especially for the application of materials under extreme temperature changes.

Effects of primer components of silane and 10-methacryloyloxydecyl dihydrogen phosphate on resin bonding to tribochemical silica-coated highly translucent zirconia.

To assess the influence of different primer compositions-silane (S), 10-methacryloyloxydecyl dihydrogen phosphate (MDP), and the combination of silane and MDP (S + MDP)-on the bonding performance of MDP-free and MDP-containing resin cements to highly translucent zirconia. Tribochemical silica-coated zirconia plates were pretreated with one of three experimental primers, S, MDP, or S + MDP, with untreated specimens serving as controls. Subsequently, these plates were bonded to stainless-steel rods using either two MDP-free or two MDP-containing resin cements. Tensile bond strength was measured after 24h (TC0) and following thermal cycling (4-60°C for 10,000 cycles; TC10,000). Data were analyzed using a three-way analysis of variance (ANOVA), followed by one-way ANOVA and Tukey-Kramer post hoc tests (α = 0.05). X-ray photoelectron spectroscopy (XPS) assessed the elemental mass concentrations on the zirconia surfaces. For MDP-free resin cements, MDP-treated specimens exhibited significantly greater bond strengths than controls, regardless of the aging conditions. However, a significant reduction in bond strength was observed between TC0 and TC10,000 in most of the MDP-free resin cement groups, except for one S + MDP group. Conversely, for MDP-containing resin cements, the S + MDP group exhibited no statistically significant differences between aging conditions. Notably, XPS analysis detected silicon, zirconium, and aluminum on the zirconia surfaces. No significant difference in tensile bond strength was observed between aging conditions for MDP-containing resin cements bonded to tribochemical silica-coated zirconia primed with S + MDP. The combination of MDP-containing primers and resin cements demonstrated superior bonding performance to tribochemical silica-coated zirconia.

Material Flow Behavior and Thermal Cycle during Friction Stir Welding of AA5083/AZ91 Dissimilar Metals

Material Flow Behavior and Thermal Cycle during Friction Stir Welding of AA5083/AZ91 Dissimilar Metals

Effect of trace oxygen on smelter off‐gas reduction desulphurization process over FeSx/γ‐Al2O3 catalysts

AbstractEffects of trace oxygen on iron sulphides‐supported catalysts (FeSx/γ‐Al2O3) were evaluated through smelter off‐gas reduction process for sulphur synthesis. Catalytic performance was evaluated under different oxygen content conditions. The properties of fresh and used catalysts were investigated by means of X‐ray diffraction (XRD), thermogravimetry‐differential thermal analysis (TG‐DTA), X‐ray photoelectron spectroscopy (XPS), and elemental analysis and relationships of active phases and activity were analyzed. The relationship between different active crystal crystals (FeSx, FeS2, Fe, FeO, γ‐Fe2O3) and SO2/O2 adsorption and conversion was investigated. The mechanism of oxygen influence on the FeSx/γ‐Al2O3 surface was given and the lifetime of the catalyst in the reaction atmosphere close to real smelter off‐gas after dust and oxygen removal steps containing trace oxygen (0.5 O2 v/v.%) was explored.

DECOMPOSITION MECHANISM OF ALKYLIDENE BRIDGED TETRAZOLES WITH DIFFERENT CARBON CHAIN LENGTHS.

Nitrogen-rich heterocycles, particularly tetrazole-based high-energy density materials (HEDMs) offer high performance, low sensitivity, and are eco-friendly. Despite the diversity of nitrogen-rich energetic heterocycles, many are sensitive to external stimuli, and the introduction of a methylene, ethylene, or C-C linkage between nitrogen-rich heterocycles is a successful strategy to improve mechanical sensitivity and thermal stability. Understanding the potential anomalous thermal or kinetic behavior of such molecules is crucial for the design of new HEDMs and practical applications of these molecules. We have investigated the influence of introducing an alkylidene bridge between the energetic nitrogen heterocycles on the decomposition mechanism and pathway of different bridged tetrazoles, namely 5,5'-Bis-1H-tetrazole, 1,2-Bis(5-tetrazolo)methane, and 1,2-Bis(5-tetrazolo)ethane, using thermal experiments, mass spectrometry, and computational analysis. Kinetic parameters were evaluated using a non-linear integral method, and decomposition pathways were proposed based on mass fragmentation data. Stability comparisons were made using HOMO-LUMO gap and electrostatic potential (ESP) values from computational calculations.