Thermogravimetric Differential Thermal Analysis Research Articles

Investigation of Molding Conditions for CNT Composite Phenolic Resin Bond by Solvent Casting Method

In this paper, we propose a new fabrication method of high concentration carbon nanotube (CNT) composite phenolic resin bond for grinding tools and investigate the molding conditions by solvent casting method. CNT/diamond composite phenolic resin grinding tools with 12.5 vol% Ni-coated diamond grains and 20 vol% CNTs were prepared by the solvent casting method. The novolac phenolic resin with Hexamethylenetetramine as a hardener was used in this study. Partial curing of this resin occurs in the range of 40°C–90°C and harden completely at 180°C. The proposed solvent casting method involves two steps: desolvation and hot press for molding. Methanol or butanol was used as the solvent. When methanol solvent was used, desolvation was performed below 90°C before partial curing of phenol was completed. When butanol solvent was used, desolvation was performed at 100°C after partial curing of phenol. The effect of solvent and desolvation temperature on mechanical strength was determined from four-point bending tests. The porosity of the grinding tools was estimated by X-ray CT analysis, and the relationship between the porosity and mechanical strength was clarified. The effect of addition of CNTs on the phenolic curing process was also clarified by thermogravimetric-differential thermal analysis and Fourier-transform infrared spectroscopy. The mechanical strength of the grinding tools fabricated using methanol solvent and desolvated at room temperature and 40°C was approximately 70 MPa, and twice as high as that desolvated at 70°C. The mechanical strength of the grinding tools fabricated using butanol solvent and desolvated at 100°C was also 70 MPa. There was no difference in the dispersibility of diamond abrasive grains between the methanol and butanol samples; however, the porosity tended to be less in the butanol solvent. This study confirmed that the mechanical strength of CNT/diamond composite phenolic resin is affected by the amount and size of the voids. In particular, it was shown that better strength can be obtained by desolvation to avoid partial curing. The addition of CNTs may inhibit the curing reaction of phenol and hexamine owing to the glycidyl groups, which are functional groups of CNTs.

Design of LaMnO3/rGO composite electrode materials for high-performance energy storage devices

Design of LaMnO3/rGO composite electrode materials for high-performance energy storage devices

Enhanced performance in SOFC cathodes via B‐site co‐dopant switching in PBSCF0.25 and PBSFC0.25 layered perovskites

AbstractTwo cathodes, PrBa0.5Sr0.5Fe1.75Co0.25O5+δ (PBSFC0.25) and PrBa0.5Sr0.5Co1.75Fe0.25O5+δ (PBSCF0.25), were synthesized by a wet chemistry route through complexing agent's process. Thermogravimetric analysis and differential thermal analysis were done for the uncalcined powders to observe the thermal behavior. Pure single‐phase structures of the compounds were obtained after a final sintering temperature of 1100°C for 5 h. Samples were crystallized in the orthorhombic structure in the space group (Pmmm). Scanning electron microscope and EDS analysis show the crystalline composites with excellent porosity percentages. The porosity was higher in PBSFC2.5 than PBSCF0.25. Conductivities of two cathodes were examined in air environment from 500 to 800°C with an interval of 50°C. It has found that PBSFC0.25 is higher in conductivity of 3.0068 S/cm with less polarization resistance of 0.05 Ω than PBSCF0.25 with conductivity of 2.306 S/cm and polarization resistance of 0.066 Ω. PBSFC0.25 has shown a reasonable enhancement in performance of 0.699 W/cm2 at 800°C, higher than PBSCF0.25 (0.608 W/cm2) at the same temperature. Even at 600°C, the power density of PBSFC0.25 was 0.245 W/cm2, higher than the PBSFC0.25, which was found to be 0.220 W/cm2. Thereby, PBSFC2.5 is recommended to be a good candidate for air electrode at the intermediate range temperature.

A novel 2D nickel coordination polymer based on Trimesic acid with glyphosate coordination capabilities

This work presents the synthesis and characterization of a novel coordination polymer entitled Ni-BTC, using nickel as metallic centers and Trimesic Acid (H₃BTC) as linkers. This new structure was characterized using Single Crystal X-ray Diffraction (SCXRD), exhibiting a MOF (metal–organic framework) structure, with a minimal formula of {[Ni(HBTC)(DMF)₂]·xDMF}. The structure exhibits a 2D network expanding in the equatorial direction, where the Ni(II) center is hexacoordinated and N,N'-dimethylformamide (DMF) solvent molecules are coordinated along the axial axis. Additionally, a Co-BTC coordination polymer was synthesized, with an already known structure similar to Ni-BTC, given the coordination modes of the BTC and DMF ligands. The structure of Ni-BTC is also a pseudo-polymorph of the previously published MOF [Ni(HBTC)(DMF)₂·(guest)] (3). The crystallographic data illustrate the structural differences. Ni-BTC was also analyzed by Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (FESEM-EDS), revealing two different phases, one containing chloride anions originating from the precursor salt NiCl₂∙6H₂O. Upon substitution of this precursor with Ni(NO₃)₂∙6H₂O, only one phase was observed, indicating the influence of the counter-ion in modulating new phases during synthesis. Ni-BTC was further characterized by thermal methods such as Thermogravimetric Analysis and Differential Thermal Analysis (TGA and DTA), showing moderate thermal resistance. The Magnetic Susceptibility data indicated a + 2 state for both metal centers. Finally, the bidentate molecule Glyphosate (GLY), widely used as a pesticide and recognized as an environmental pollutant, was employed for coordination with Ni-BTC, as in this structure, the axial DMF ligands are labile and can be replaced by glyphosate molecules. This coordination capability was demonstrated by Powder X-ray Diffraction (PXRD) and Infrared Spectroscopy (FTIR), along with electrochemical techniques such as Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV), thus confirming glyphosate coordination in Ni-BTC, with potential applications in detection and removal systems.Graphical

Synthesis and properties of carbon black (CB)-added polyacrylonitrile (PAN)/nickel foam (NF) flexible electrodes by electrospinning, and their supercapacitive performance

This research study presents the successful preparation of polyacrylonitrile/nickel foam (PAN/NF) and carbon black (CB)-added polyacrylonitrile/nickel foam (CB:PAN/NF) electrodes using an electrospinning method, along with a comprehensive discussion of their remarkable supercapacitive performances. Scanning electron microscope (SEM) investigations demonstrate a robust adhesion between polyacrylonitrile fibers and nickel foam, attributable to the application of an annealing process. Energy dispersive X-ray spectrometry (EDS) studies validate the elemental composition of the electrodes. To further characterize the structural properties, additional analyses are conducted utilizing X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Structural characterizations indicate that both the incorporation of carbon black and the carbonization process yield beneficial contributions to the overall material properties. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are employed to evaluate the thermal stability of the electrodes. Electrochemical investigations are performed using various techniques such as cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS), and Mott-Schottky (MS), all in a 1 M aqueous KOH solution. The addition of carbon black (CB) significantly improves the performance of the PAN/NF electrode, increasing the specific capacitance from 76.5 to 226.9 F g−1. This study also examines the reaction kinetics that characterize the energy storage mechanisms of the electrodes. The enhancement of the electroactive surface area in PAN/NF due to CB loading is also confirmed by EIS analysis. In the existing literature, many studies focus on the direct use of PAN and its derivatives as electrode materials. However, this study is the first to investigate the energy storage capabilities of PAN in combination with a current collector, specifically nickel foam (NF). The results of this study provide strong evidence for CB:PAN/NF as a promising electrode material in flexible supercapacitors.

Removal of Primamycin La from Milk Sample Using ZnCl2-Activated Biochar Prepared from Bean Plant as Adsorbent: Kinetic and Equilibrium Calculations

In this study, porous biochar (PvBC) was obtained by the pyrolysis of bean (phaseolus vulgaris) plant at 600 °C, and then activated biochar (PvBCZn) was synthesized by ZnCl2 activation at an equal biomass ratio (1.0:1.0). Some analytical techniques (SEM-EDX (scanning electron microscopy–energy dispersive X-ray spectroscopy), TGA/DTA (Thermogravimetric/Differential Thermal Analysis), BET (Brunauer–Emmett–Teller), FTIR (Fourier Transform Infrared Spectroscopy) and XRD (X-ray diffraction)) were used to characterize both PvBC and PvBCZn. In addition, their antibiotic sensitivity, water solubility, moisture content and swelling behavior were investigated in detail. Furthermore, both PvBC and PvBCZn were used for the adsorption of primamycin la, an anti-inflammatory drug used in veterinary medicine whose active ingredient is oxytetracycline, in a milk sample. The effect of both pH and adsorbent dosage on the adsorption capacity was investigated. Based on adsorption studies, while the maximum adsorption capacity (qmax) of PvBCZn was found to be 188.48 mg/g, that of PvBC was found to be 122.49 mg/g. According to these results, PvBCZn is an excellent adsorbent for the removal of primamycin la from milk samples. The Langmuir isotherm model and the pseudo-second-order kinetic model were more suitable to describe the adsorption behavior of primamycin la. The PvBCZn adsorbent exhibited rapid removal exceeding 75% in the first 20 min and reached equilibrium after about 50 min. In addition, studies on the desorption and reusability of PvBCZn were carried out under the same optimum experimental conditions. The qmax value of PvBCZn was found to be 171.40 mg/g even in the fifth cycle, confirming the idea that it is a potential adsorbent for the removal of primamycin la. At the same time, the antimicrobial activity of PvBCZn against Escherichia coli bacteria increases its potential to be used in both purification systems and hygiene products.

Quantitative Estimation of Effective Brønsted Acid Sites of Silica-Supported H4SiW12O40 Heteropoly Acid for Adsorption of Various Molecules.

The amount of incorporation of linear alcohols and ethers in H4SiW12O40·6H2O (HSiW·6H2O, 50 wt %) supported on silica (SiO2) was estimated by a conventional volumetric method and infrared (IR) spectroscopy, and the state of involved molecules was elucidated. First, the attribution of the key IR band at 2200 cm-1, which was observed for the water of crystallization of HSiW·6H2O, to H5O2+ species (protons) was verified by coincident observation of thermogravimetric-differential thermal analysis, X-ray diffraction (XRD), and IR spectroscopy during thermal treatment in addition to the isotope exchange with D2O. The 2200 cm-1 band was gradually decreased in intensity by increasing the amount of adsorption of pyridine and was totally consumed at saturation, while the volumetric method provided the accurate number of included pyridine molecules. Thus, the decrease of the integrated intensity of the 2200 cm-1 band was employed to evaluate the extent of interaction of linear alcohols and ethers with H5O2+ species in equilibrium and irreversible conditions at room temperature. Linear alcohols (C1-C5) consumed almost all protons in equilibrium and about 50% in evacuation at room temperature, while about a half of protons were interacted in equilibrium and a quarter in evacuation in the case of dimethyl and diethyl ethers. Knowing the number of molecules incorporated and the amount of H5O2+ species consumed, the ratio of interacted molecules and H5O2+ species was estimated as H5O2+:molecules = 1:2-3. XRD patterns indicated the copresence of molecule-incorporated and molecule-free domains under irreversible conditions. Therefore, the incorporated molecules were concentrated around the H5O2+ species in HSiW·6H2O crystals. The state of absorbed molecules in HSiW·6H2O crystals was presumed by IR spectra: the presence of Fermi resonance of the hydrogen-bonded OH stretching band of H5O2+ species with CH deformation bands of interacted molecules implied the equilibrium state of as-interacted molecules and protonated species (transition state) at room temperature.

Electrochemical Sensor Based on CoMgFe-Trimetallic Layered Double Hydroxides for Flubendiamide Detection in Water Samples

Abstract Flubendiamide (FBD) is a widely used insecticide in agriculture, known for its effectiveness in controlling crop pests. However, its use presents significant risks to both the environment and human health. In this study, a novel pencil graphite electrode (PGE) was successfully modified with CoMgFe trimetallic layered double hydroxides (CoMgFe-TLDHs) to achieve sensitive and selective electrochemical detection of 20% FBD, a toxic insecticide posing ecological and health concerns. The CoMgFe-TLDHs were synthesized using a simple co-precipitation method and characterized by thermogravimetric differential thermal analysis, X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. These materials were then applied to the PGE surface, significantly enhancing its electrochemical performance, as demonstrated by differential pulse voltammetry and cyclic voltammetry. Under optimized conditions, PGE/ionic liquid/CoMgFe-TLDHs electrode exhibited excellent analytical properties toward FBD determination. A calibration curve was well-established from 0.8 to 100 µM for FBD with a detection limit of 0.36 μM. The proposed sensor enabled the practical application of sensitive FBD detection in tape and river water with good recovery rates.

Characteristics of naturally woven Waru bark fiber for eco-friendly composite reinforcement.

Characteristics of naturally woven Waru bark fiber for eco-friendly composite reinforcement.

Exploring a new Portland cement-free calcium silicate cement -Part 1: Synthesis of dicalcium and tricalcium silicate.

Mineral trioxide aggregate cement is an excellent pulp-capping material; however, its base Portland cement contains highly toxic elements and is expensive. This study aimed to explore the possibility of using calcium silicate cement without Portland cement. Synthesis was attempted via firing using calcium silicate (CS), as the base material, and calcium oxide (CA). According to the chemical reaction, they were weighed and sintered in an electric furnace at a sintering temperature of 1,300ºC based on the results of thermogravimetric differential thermal analysis. The powder composition after firing was examined by X-ray diffraction analyses. Compressive tests were performed using a universal testing machine. The sintered powders were confirmed as dicalcium silicate (CS2) and tricalcium silicate (CS3); however, some peaks were detected and their compressive strengths were lower than that of CS. These results suggest that CS2 and CS3 were successfully synthesized from a mixture of CA and CS.

Enhancing the protective performance of organic coatings for marine applications with nepheline-epoxy resin composites

PurposeThe marine environment presents a great challenge to the anticorrosion properties of organic coatings applied on equipment. Since the compactness of coatings is critical in marine environments, a novel nepheline-epoxy resin (N-EP) composite was introduced into organic coatings to improve the interfacial compatibility between the pigments and the binder. The purpose of this study is to evaluate the effectiveness of the N-EP composite in enhancing the corrosion resistance of the coatings in marine conditions.Design/methodology/approachThese composite particles were prepared via the mechanical ball milling method at thermofield-assisted, leading to chemical bonding between inorganic nepheline and epoxy resin, the agglomeration of particles was avoided by this method. Fourier transform infrared spectroscopy, transmission electron microscope, particle size distribution, sedimentation and thermogravimetric-differential thermal analysis were used to verify the feasibility of thermal field-assisted mechanochemistry for achieving a direct reaction between epoxy resin and nepheline powder, as well as to determine the optimal reaction conditions. Additionally, water absorption tests, Electrochemical impedance spectroscopy and scanning electron microscope were conducted to assess the anticorrosive properties of the modified nepheline coatings.FindingsThe results further indicated that N-EP improved the barrier performance and mechanical properties of the coating. For example, after modified, the tensile strength of coating had increased from 41.96 ± 0.05–63.14 ± 0.05 MPa. This can be attributed to the less defective N-EP/binder interface and the uniform dispersion of N-EP in the coating. The optimal preparation conditions (500 r/min of ball grinding speed and 6 h of ball grinding time) for the composites were also studied for a superior corrosion resistance of the coating.Originality/valueThermofield-assisted mechanochemistry enables direct reactions between epoxy resin and nepheline powder, enhancing the dispersion stability and interfacial compatibility of N-EP. This modification improves coating compactness, reduces porosity and enhances corrosion resistance by strengthening the labyrinth effect on water diffusion.

Ammoxidation of Benzaldehyde Under Atmospheric Molecular Oxygen by Use of Mn-Al Mixed Oxide Catalyst Derived from Nitrate-Intercalated Mn2+-Al3+ Layered Double Hydroxide

ABSTRACT The nitrate-intercalated Mn2+-Al3+ layered double hydroxide, denoted as NO3 −/Mn2Al LDH (Mn2+/Al3+ = 2/1 at preparation) was successfully synthesized through the coprecipitation method. Upon calcination of the NO3 −/Mn2Al LDH at 473 K under air, the LDH structure collapsed, as evidenced by in-situ temperature-programmed synchrotron X-ray diffractrion (tp-SXRD) and thermogravimetric-differential thermal (TG-DTA) analysis. The collapse of the hydroxide nanosheet containing Mn2+ decomposed into generated Mn-Al mixed oxide (Mn2AlO), which mainly contained nanosized Mn3O4, as indicated by in-situ Mn K-edge X-ray absorption near-edge structure (XANES) spectra. The Mn2AlO_773, obtained via calcination of the NO3 −/Mn2Al LDH at 773 K, acted as an efficient catalyst in the ammoxidation of benzaldehyde with ammonium acetate as a nitrogen donor under atmospheric molecular oxygen. The main component of Mn oxide species in the Mn2AlO_773 matrix was Mn3O4, confirmed by the linear combination fitting (LCF) calculation of Mn K-edge XANES spectrum. The synthesized Mn2AlO_773 catalyst was reusable without any loss of its activity and selectivity.

Effects of Rock Water with Different Alkalinity and Pre-Oxidation on Re-Ignition Characteristics of Residual Coal

ABSTRACT To investigate the impact of alkaline rock water (pH = 8, 9) combined with pre-oxidation on changes in pore structure and functional groups of residual coal in goaf, and consequently, on the secondary oxidation and spontaneous combustion characteristics of coal samples, an analysis was conducted. This analysis focused on examining changes in pore morphology and functional group content of pre-oxidized coal (OI0) and water-immersed oxidized coal (OI) through experiments utilizing low-temperature nitrogen adsorption and in-situ diffuse reflectance infrared spectroscopy. Secondary oxidation and spontaneous combustion characteristics of coal samples were analyzed using thermogravimetric differential thermal analysis incorporating oxidation kinetic theory. The findings indicated that after the combined effect of pre-oxidation and alkali leaching, the mesopore volume of the coal decreased, pore complexity increased, oxygen storage capacity was enhanced, and the apparent activation energy of the coal samples was significantly reduced. This reduction in activation energy was pronounced at lower temperatures but less so at higher temperatures. Specifically, the methyl and methylene contents of OI9 were significantly higher than those of other coal samples within the temperature range of 80–160°C. Meanwhile, the heat release of the low-temperature oxidation stages of OI0, OI8, and OI9 increased by 70.82%, 190.25%, and 75.05%, respectively, compared with RC. The study indicates an elevated risk of spontaneous coal combustion following the combined treatment of alkaline leaching and pre-oxidation. This research elucidates the mechanism of spontaneous combustion of water-immersed coal by alkaline rock water and pre-oxidation, providing valuable insights for the control of coal fires in alkaline mine-water environments.

Synthesis and characterization of multi-responsive iron oxide nanoparticles: Evaluation of antibacterial properties and photocatalytic activity

Synthesis and characterization of multi-responsive iron oxide nanoparticles: Evaluation of antibacterial properties and photocatalytic activity

Synthesis and characterization of thermal properties of poly(p-cumylphenyl methacrylate-co-methoxyethyl methacrylate) copolymers

Synthesis and characterization of thermal properties of poly(p-cumylphenyl methacrylate-co-methoxyethyl methacrylate) copolymers

Green Synthesis of Al-ZnO Nanoparticles Using Cucumis maderaspatanus Plant Extracts: Analysis of Structural, Antioxidant, and Antibacterial Activities.

Nanoparticles derived from biological sources are currently garnering significant interest due to their diverse range of potential applications. The purpose of the study was to synthesize Al-doped nanoparticles of zinc oxide (ZnO) from leaf extracts of Cucumis maderaspatanus and assess their antioxidant and antimicrobial activity using some bacterial and fungal strains. These nanoparticles were analyzed using X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and thermogravimetric analysis/differential thermal analysis (TG-DTA). The average crystalline size was determined to be 25 nm, as evidenced by the XRD analysis. In the UV-vis spectrum, the absorption band was observed around 351 nm. It was discovered that the Al-ZnO nanoparticles had a bandgap of 3.25 eV using the Tauc relation. Furthermore, by FTIR measurement, the presence of the OH group, C=C bending of the alkene group, and C=O stretching was confirmed. The SEM analysis revealed that the nanoparticles were distributed uniformly throughout the sample. The EDAX spectrum clearly confirmed the presence of Zn, Al, and O elements in the Al-ZnO nanoparticles. The TEM results also indicated that the green synthesized Al-ZnO nanoparticles displayed hexagonal shapes with an average size of 25 nm. The doping of aluminum may enhance the thermal stability of the ZnO by altering the crystal structure or phase composition. The observed changes in TG, DTA, and DTG curves reflect the impact of aluminum doping on the structural and thermal properties of ZnO nanoparticles. The antibacterial activity of the Al-ZnO nanoparticles using the agar diffusion method showed that the maximum zone of inhibition has been noticed against organisms of Gram-positive S. aureus compared with Gram-negative E. coli. Moreover, antifungal activity using the agar cup method showed that the maximum zone of inhibition was observed on Aspergilus flavus, followed by Candida albicans. Al-doping nanoparticles increases the number of charge carriers, which can enhance the generation of reactive oxygen species (ROS) under UV light exposure. These ROS are known to possess strong antimicrobial properties. Al-doping can improve the crystallinity of ZnO, resulting in a larger surface area that facilitates more interaction with microbial cells. The structural and biological characteristics of Al-ZnO nanoparticles might be responsible for the enhanced antibacterial activity exhibited in the antibacterial studies. Al-ZnO nanoparticles with Cucumis maderaspatanus leaf extract produced via the green synthesis methods have remarkable antioxidant activity by scavenging free radicals against DPPH radicals, according to these results.

Efficient Catalytic Reduction of Organic Pollutants Using Nanostructured CuO/TiO2 Catalysts: Synthesis, Characterization, and Reusability

The catalytic reduction of organic pollutants in water is a critical environmental challenge due to the persistent and hazardous nature of compounds like azo dyes and nitrophenols. In this study, we synthesized nanostructured CuO/TiO2 catalysts via a combustion technique, followed by calcination at 700 °C to achieve a rutile-phase TiO2 structure with varying copper loadings (5–40 wt.%). The catalysts were characterized using X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR–FTIR) spectroscopy, thermogravimetric analysis-differential thermal analysis (TGA–DTA), UV-visible diffuse reflectance spectroscopy (DRS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS). The XRD results confirmed the presence of the crystalline rutile phase in the CuO/TiO2 catalysts, with additional peaks indicating successful copper oxide loading onto TiO2. The FTIR spectra confirmed the presence of all the functional groups in the prepared samples. SEM images revealed irregularly shaped copper oxide and agglomerated TiO2 particles. The DRS results revealed improved optical properties and a decreased bandgap with increased Cu content, and 4-Nitrophenol (4-NP) and methyl orange (MO), which were chosen for their carcinogenic, mutagenic, and nonbiodegradable properties, were used as model organic pollutants. Catalytic activities were tested by reducing 4-NP and MO with sodium borohydride (NaBH4) in the presence of a CuO/TiO2 catalyst. Following the in situ reduction of CuO/TiO2, Cu (NPs)/TiO2 was formed, achieving 98% reduction of 4-NP in 480 s and 98% reduction of MO in 420 s. The effects of the NaBH4 concentration and catalyst mass were investigated. The catalysts exhibited high stability over 10 reuse cycles, maintaining over 96% efficiency for MO and 94% efficiency for 4-NP. These findings demonstrate the potential of nanostructured CuO/TiO2 catalysts for environmental remediation through efficient catalytic reduction of organic pollutants.

The effects of filling method on silicone rubber composites filled with SiO2 and TiO2

Silica (SiO₂) serves as a reinforcing filler, while titanium dioxide (TiO₂) functions as a functional filler, imparting exceptional mechanical strength and UV resistance to silicone rubber. However, compatibility issues may arise when both fillers are incorporated into silicone rubber. This study explores potential solutions through processing methods, specifically by comparing the effects of graded filling and mixed filling on the properties of silicone rubber. Field emission scanning electron microscopy reveals that the mixed filling method promotes a more uniform dispersion of fillers, leading to enhanced performance. Curing tests indicate that the effect of the filling method on the curing processing performance of silicone rubber is negligible. Tensile test results reveal that, compared to the graded filling system, the mixed filling system improves the tensile strength and elongation at break of the silicone rubber composites by 13% and 13.4%, respectively, while simultaneously reducing the Mullins effect, thereby enhancing material stability. Thermogravimetric analysis (TGA) and differential thermal analysis (DTG) results indicate that the uniform dispersion achieved through mixed filling optimizes thermal transfer pathways, resulting in superior thermal stability compared to graded filling. Ultraviolet (UV) spectroscopy results demonstrate that composites containing added TiO₂ exhibit almost zero transmittance in the UV range of 200-400 nm, underscoring their excellent UV resistance; the mixed filling method provides superior UV protection compared to the graded fill method. In summary, for the dual-filler system of SiO₂ and TiO₂, the mixed filling approach enhances filler compatibility by improving dispersion, thereby elevating material performance and broadening potential applications.

Low-cost preparation and characterization of new CuO/ZnO and Cu3N/ZnO nanocomposites

Low-cost preparation and characterization of new CuO/ZnO and Cu3N/ZnO nanocomposites

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.