Simultaneous Differential Scanning Research Articles

Preparation of Si@PVDF composite microspheres by electrostatic spraying for enhanced energetic characteristics

In this study, Si@PVDF composite microspheres are prepared by the electrostatic spraying method. The spheres are with average diameter of around 2 μm (when at ideal stoichiometry), within which Si nanopowder is uniformly distributed. The exothermic properties of samples are studied through simultaneous thermogravimetry and differential scanning calorimetry. Benefiting from the improved interfacial contact quality, Si@PVDF shows increased chemical reactivity in terms of reduced reaction onset temperature, peak temperature and apparent activation energy than those of physically mixed Si/PVDF counterpart. Si/PVDF cannot be ignited through Joule heating, either in the powder of pellet form, while self-sustained combustion propagation is observed for Si@PVDF pellets. The combustion behaviors of Si@PVDF pellets are systematically studied in open-air (where light signal is analyzed) and constant-volume (where pressure signal is analyzed) conditions. The results show that the combustion process is influenced by the equivalence ratio, porosity of the pellet and the accessibility of O2 gas in the environment. Overall, the encapsulation of Si nanopowder into PVDF microspheres using electrostatic spraying shortens the mass and heat transfer distance and thus realizes enhanced energetic characteristics.

Asymmetric anion effects of anions in ionic liquids: Crystal polymorphs and magnetic properties

In this study, the phase transitions and magnetic properties of magnetic ionic liquids (mILs) were investigated at low temperatures. The mILs were [Cnmim]2[MnCl4-mBrm] (n = 2, 3, and 4; m = 0, 1, 2, 3, and 4), where [Cnmim]+ is 1-alkyl-3-methylimidazolium. Here, simultaneous X-ray diffraction and differential scanning calorimetry were used to determine the crystal polymorphs in the mILs. The results showed that shorter alkyl chain lengths of cations and symmetric anions aided crystallization. Melting points in [C2mim]2[MnCl4-mBrm] were also found to be strongly dependent on asymmetric anionic configurational and cationic conformational entropies. Furthermore, the asymmetric anion effect contributed slightly to the paramagnetic properties of mILs.

Polypropylene film surface modification for improving its hydrophilicity for innovative applications

Organic polymeric materials, especially polyolefins, contain mainly C and H atoms and thus present serious surface problems due to low surface energy and reactive inertness. Using method developed in this work it is possible to convert the H atoms of the polypropylene (PP) film surface into polar groups by treatment with a mixture of chromic, sulphuric, and phosphoric acids in a short time at elevated temperature. Hydroxyl and carboxyl groups on the surface of materials not only determine their chemical and physical properties, but also provide reactive centers for various applications. Optical microscopy (OM) and atomic force microscopy (AFM) analyses have shown that induced surface modification of the PP film causes mainly physical changes, creating microcraters and surface roughness and hence increasing surface tension, while X-ray diffraction (XRD) analysis has confirmed the absence of phase changes. The attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy analysis has confirmed the grafting of polar groups, such as hydroxyl, carboxyl, and carbonyl onto the surface of the PP. This indicates that used mixture destroyed or at least broke down to some extent the covalent bonds of the main carbon skeletons, which were present on PP substrate surfaces and improved surface wettability and zeta potential. The simultaneous thermal analysis (thermogravimetry (TG) and differential scanning calorimetry (DSC)) results have shown that the presence of polar groups in the PP-[O] film samples affects the melting and decomposition temperatures; they are higher than those of PP film. The change in the enthalpy of melting indicated a change in the surface energy. The band gap (Eg) determined from diffuse reflectance spectra in the UV-visible region by the Kubelka-Munk method has decreased for modified PP films, and they have become more suitable for optoelectronics.

Thermodynamic characterization of LF, H, and mineral soil layers from oak forest ecosystems: Exploring the role of proximate analysis

Studying the thermodynamic properties of soil organic matter is a developing field that involves the measurement of the energy stored by the soil. Quantifying soil energy content is still challenging despite different methodological approaches are available to calculate that value. One of the options is the proximate analysis following the guidelines for the energetic characterization of biomass. However, proximate analyses are still unexplored for soils. In this paper, we investigate the potential of this analysis to contribute to study soil from a thermodynamic perspective. With that goal, 31 soil samples collected in mature oak forests following a depth transect were used for elemental, thermal and proximate analysis. Proximate analyses and energetic characterization were performed by simultaneous thermogravimetry and differential scanning calorimetry.These methods allowed fragmentation of the soil organic matter in water content, volatile matter, fixed carbon, and ash, as well as the quantification of the soil organic matter and energy content. Pearson's correlation showed significant relations among the proximate, the elemental components of soils and the energy. The equations relating all of these variables were calculated for soils from oak forests by partial least squares analysis. Equations representing the relationship between energy and the proximate fractions provide an additional alternative to calculate the heat of combustion of the soil organic matter. This value is the essential step for the thermodynamic characterization of soils.

Flujo de calor y capacidades calorífica específica en la etapa de deshidratación de la pirólisis de biomasas por análisis térmicos

This study aims to investigate the influence of the moisture of energy cane and coconut fiber on heat flow and specific heat capacity in the dehydration stage from the pyrolysis process. The experiments were carried out in a simultaneous thermogravimetry and differential scanning calorimetry analyzer using a heating rate of 20 K/min in an inert atmosphereThree decomposition stages were identified: dehydration (marked by an expressive endothermic peak), pyrolysis, and carbonization). From the analyses of the water contributions, it was observed that the heat flow from the heat capacity of remaining water (Qwc) is negligible compared to the heat flow from the water evaporation (Qwe), for both biomasses. Also, we calculated the heat flow from the heat capacity (Qb) and the experimental specific heat capacity (cp,b) of biomasses such as 686-2371 J/kg K and 1076-2113 J/kg K, respectively. Then, for the dehydration stage, third- and fourth-order theoretical polynomial equations have been proposed to predict the heat required for the biomass heating.

Personalised Esomeprazole and Ondansetron 3D Printing Formulations in Hospital Paediatric Environment: I-Pre-Formulation Studies

Individualised medicine demands the formulation of pharmacotherapy in accordance with the characteristics of each patient’s health condition, and paediatrics is one of the areas that needs this approach. The 3D printing of oral doses is one method for achieving customised medicine in paediatrics. In this work, pre-formulation studies were conducted to evaluate the viability of using specific raw materials to produce 3D printed dosage forms based on two active pharmaceutical ingredients (APIs), ondansetron and esomeprazole, which are important for therapeutic customisation in paediatrics. Pre-formulation studies were carried out by characterising the physical and chemical properties of selected raw materials, selected APIs and their mixtures, using analytical methods such as scanning electron microscopy (SEM), X-ray powder diffraction (X-RPD), simultaneous thermal analysis (STA) and differential scanning calorimetry (DSC). The flowability of powders, compatibility and stability studies were also performed. Among all the ingredients selected, the PVPs (K17, K25 and K90) had the best characteristics to incorporate both forms of Esomeprazole Mg in a formulation to produce extrudates. The results obtained validated the use of some selected raw materials for tablet manufacture by the 3D printing approach.

Preliminary Study on Characteristics of NC/HTPB-Based High-Energy Gun Propellants

This study mainly explored the characteristics of NC/HTPB-based high-energy gun propellants with RDX, CL-20 or TKX-50 by experimental method. Three series of test samples were prepared referring to the formulation of M1 single-base gun propellant (M1 SBP). The thermochemical characteristics, chemical stability, explosion heat, impact and friction sensitivities of prepared samples were determined by simultaneous differential scanning calorimetry–thermogravimetric analysis (STA DSC–TGA), vacuum stability tester (VST), bomb calorimeter (BC), BAM fallhammer and BAM friction tester, respectively, and compared with those of the reference sample M1. The experimental results indicated that the thermochemical characteristics of NC/HTPB-based high-energy gun propellants were similar to those of M1 SBP. The NC/HTPB-based high-energy gun propellants had good chemical stability and were superior to M1 SBP. The explosion heat of NC/HTPB-based high-energy gun propellants was close to and slightly larger than that of M1 SBP. In addition, the NC/HTPB-based high-energy gun propellants had lower impact and friction sensitivities than the M1 SBP. Therefore, the NC/HTPB-based high-energy gun propellants have the potential to replace the M1 SBP. The combustion performances of NC/HTPB-based high-energy gun propellants will be continuously studied and verified in the future.

Temperature-dependent compatibility study on halide solid-state electrolytes in solid-state batteries.

All-solid-state lithium batteries (ASSLBs) have attracted much attention owing to their high safety and energy density compared to conventional organic electrolytes. However, the interfaces between solid-state electrolytes and electrodes retain some knotty problems regarding compatibility. Among the various SSEs investigated in recent years, halide SSEs exhibit relatively good interfacial compatibility. The temperature-dependent interfacial compatibility of halide SSEs in solid-state batteries is investigated by thermal analysis using simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC) and X-ray diffraction (XRD). Halide SSEs, including rock-salt-type Li3InCl6 and anti-perovskite-type Li2OHCl, show good thermal stability with oxides LiCoO2, LiMn2O4, and Li4Ti5O12 up to 320 °C. Moreover, anti-perovskite-type Li2OHCl shows a chemical reactivity with other battery materials (eg., LiFePO4, LiNi0.8Co0.1Mn0.1O2, Si-C, and Li1.3Al0.3Ti1.7(PO4)3) at 320°C, which reaches the melting point of Li2OHCl. It indicated that Li2OHCl has relatively high chemical reactivity after melting. In contrast, rock-salt-type Li3InCl6 shows higher stability and interfacial compatibility. This work delivers insights into the selection of suitable battery materials with good compatibility for ASSLBs.

Sol–Gel Synthesis, Thermal Characterization, Surface Interactions, and Release Kinetics of Silica/Drug Hybrid System

AbstractControlled and local drug delivery systems of anti‐inflammatory agents are attracting increasing attention thanks to their possible pharmaceutical and biomedical applications. These systems have extended therapeutic effects and reduced side effects.The aim of this work is to synthesize a system composed of SiO2 glass and ketoprofen, an anti‐inflammatory drug, by the sol–gel process. Two different percentages (5 and 15 wt%) of drug are entrapped in the silica matrix via the sol–gel method and the dried material are analyzed via Fourier transform infrared spectroscopy (FTIR) and simultaneous Differential Scanning Calorimetery/Thermogravimetric analysis (DSC/TGA). The drug release kinetics of the amorphous bioactive materials are investigated. Molecular Mechanics and Molecular Dynamics simulations are currently in progress to investigate possible interactions between the silica‐based surface and the ketoprofen molecules both at low and high concentration for comparison with experimental data.

Reticulated porous lanthanum strontium manganite structures for solar thermochemical hydrogen production

Porous ceramic foams are utilized in various fields and applications due to their advantageous properties such as high porosity, high specific surface area, and controlled permeability. Non-stoichiometric oxide foams are of particular interest for the solar thermochemical production of hydrogen in directly irradiated solar receivers due to their enhanced heat transfer capabilities and structural integrity. We report the fabrication of lanthanum strontium manganite replica foams and their solar thermochemical water splitting performance. Highly porous (>80%) foams were produced with controlled structure and tested in a high temperature water splitting furnace to demonstrate stability and overall performance. The temperature profile of the burnout and sintering of the foam structure were altered based on simultaneous differential scanning calorimetry and thermal gravimetry analysis. Two-step sintering was used both to retain micron-sized pores (D50 = 0.4 μm) on the foam's struts and to limit grain growth to a grain size of ∼1 μm. The structural characteristics were confirmed by porosimetry and scanning electron microscopy. The foams were repeatedly cycled, producing approximately 200 μmol/g of H2 per cycle. Water splitting performance was tested for 50 cycles and approximately 35 h at 1400 °C. No statistical difference in the effective hydrogen production per cycle was observed, which is promising for long-term redox cycle stability.

Fluorosubstitution of the Molecular Core in Chiral Esters with Short Terminal Carbon Chains: Influence on Physical Properties

Comparative study of chiral liquid crystalline (S)-(1)-4’-(1-methylheptylcarbonyl) biphenyl-4-yl 4-[4-(2,2,3,3,4,4,4-heptafluorobutoxy)butyl-1-oxy] benzoate (4HH) and (S)-4’-(1-methylheptyloxycarbonyl)biphenyl-4-yl 4-[4-(2,2,3,3,4,4,4-heptafluorobutoxy) butyl-1-oxy]-2,3-difluorobenzoate (4FF) is performed by complementary methods. For 4HH melting of the low-temperature crystal phase and subsequent cold crystallization (from antiferroelectric smectic CA* phase to the high-temperature crystal phase) are reported, crystallization kinetics is examined and a monotropic hexatic SmXA* phase is observed on cooling. For 4FF rich polymorphism in the solid state is investigated mainly by simultaneous X-ray diffraction and differential scanning calorimetry measurements. Influence of fluorosubstitution on structural, electro-optic and dielectric properties of the smectic phases is reported. Unit cell parameters of crystal phases of 4HH and 4FF are determined. The reported results show that the double fluorosubstitution slows down the Goldstone mode and PH phason in the smectic phases and facilitates crystallization.

Characterization and modeling of chemical reactions taking place during the vitrification of high level nuclear waste

Several chemical reactions take place during the vitrification of high-level nuclear waste. The integration of these chemical aspects in process numerical simulation tools is one of the key points in the approach of improving the prediction capabilities of numerical tools today. In this study, based on simultaneous differential scanning calorimetry-thermogravimetry (DSC-TGA) and the run/rerun method, we propose a modeling of the kinetics of chemical reactions taking place when nuclear glass precursors are subjected to constant heating. For the mathematical modeling, a weighted sum of nth order reactions was used to describe the overall mechanism. A hybrid approach coupling the Kissinger and least squares methods was performed to identify the apparent kinetic parameters. Along with the thermal characterization, we also provide some information about the nature of the main reactions through microstructural evolution and evolved gas analyses.

Microsized aluminum/ammonium dinitramide core-shell particles to improve the combustion performance of aluminum powders

Microcomposite particles of aluminum (Al) dotted by ammonium dinitramide (ADN) ([email protected]) are successfully prepared by an in-situ crystallization growth method. The morphologies, structures and thermal behavior of [email protected] are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and simultaneous thermogravimetry and differential scanning calorimetry. The compositions and morphologies of [email protected] after heating are characterized by X-ray photoelectron spectroscopy (XPS) and SEM. A high-speed camera is used to record the combustion performances of [email protected] in a transparent quartz tube. Furthermore, the morphologies and structures of the residues are analyzed by SEM and XRD. The results show that ADN is deposited on the surface of Al to form [email protected] The decomposition of ADN increases the total oxidation degree of the Al particles. Under heating, the acids decomposed by ADN corrode the surficial alumina layer and the internal aluminum react with HNO3 to form Al(NO3)3, which makes the combustion of Al easier. Under an oxygen atmosphere, the pure Al could not be ignited. In contrast, [email protected] could be ignited and [email protected] 5:1 has a shorter ignition and burning time compared with [email protected] 10:1. After burning, the [email protected] composites are completely converted to α- and γ-Al2O3. For [email protected] 10:1, the residues show a cube-like stacking, while a ribbon-like stacking is presented for [email protected] 5:1.

Conversion of (NH4)2[ReF6] into ReO2 mixed phases: A thermal analysis study

The thermal behavior of (NH4)2[ReF6] was evaluated in an alumina crucible using simultaneous thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) in an argon atmosphere. The TGA of (NH4)2[ReF6] is characterized by a single step decomposition while the DSC exhibits two exothermic peaks. Powder X-ray diffraction (PXRD) analyses of the decomposition products show the presence of a mixed ReO2 phase. The formation of ReO2 is driven by the reaction of (NH4)2[ReF6] with Al2O3 at the grain boundary of the alumina crucible. XRD peak broadenings due to the combined effect of crystallite size and lattice strain were evaluated using both Scherrer and Williamson-Hall methods.

Nitrogen-rich energetic polymer powered aluminum particles with enhanced reactivity and energy content

Aluminum particles are of significant interest in enhancing the energy release performance of explosives. One of the major impediments to their use is that Al2O3 shell significantly decreases overall performance. To address this issue, we investigate creating aluminum particles with a glycidyl azide polymer (GAP) coating to improve their reactivity while retaining their energy content. We found that the aluminum particles were coated with a GAP layer of thickness around 8.5 nm. The coated aluminum particles were compared to non-coated powder by the corresponding reactivity parameters obtained from simultaneous differential scanning calorimetry, thermal gravimetric analysis, coupled with mass spectral and infrared spectral analyses. Besides, the comparison on the energy content was also conducted based on P–t tests and a laser-induced air shock from energetic materials (LASEM) technique. It was found that GAP shifted the oxidation onset of aluminum particles to a lower temperature by ~ 10 °C. Besides, the oxidation activation energy of aluminum particles was also reduced by ~ 15 kJ mol−1. In return, aluminum particles reduced the activation energy of the second stage decomposition of the GAP by 276 kJ mol−1. And due to the synergistic effect between aluminum and GAP, the decomposition products of GAP were prone to be oxycarbide species rather than carbonitride species. In addition, the P–t test showed the peak pressure and pressurization rate of GAP coated aluminum particles were separately 1.4 times and 1.9 times as large as those of non-coated aluminum particles. Furthermore, the LASEM experiment suggested the shock wave velocity of the GAP coated aluminum particles was larger than that of non-coated aluminum particles, and the largest velocity difference for them could be 0.6 km s−1. This study suggests after coating by GAP, the aluminum particles possess enhanced reaction performance, which shows potential application value in the fields of aluminized explosives and other energetic fields.

Evaluation of Thermal Behavior and Properties of Carbon Dots Prepared by Green Synthesis

Carbon quantum dots are highly fluorescent, non-toxic, thermally stable, and water-soluble novel carbon nanomaterials. The dominance of quantum behavior has drawn scientists’ interest due to their good biocompatibility, low toxicity, high physicochemical and photochemical stability, and ease of synthesis. Carbon dots have shown applications in optoelectronics, photovoltaics, photocatalyst, biomedical such as biosensing, bioimaging, drug delivery, and detection for heavy metal ions in food and water samples. In this paper, we reported the microwave-assisted green synthesis of carbon dots using sweet lime as a carbon source and ethyl diamine as the surface passivating agent. The change in the optical and thermal properties are studied and analyzed with a change in the concentration of EDA in carbon dots. Synthesized samples are characterized by Dynamic Light Scattering and Zeta potential particle sizer to analyze the effect of EDA concentration on the distribution of particle size in the samples and change in surface charge of as-prepared carbon dots. The optical parameters are studied with UV- Visible absorption spectroscopy. Composition and molecular bonding are confirmed by Fourier Transform Infrared Spectroscopy. Thermal behavior and kinematics are studied by simultaneous Thermogravimetric Analyzer and Differential Scanning Calorimetry.

Sensibility to chemical preparation method and thermal study of lithium zinc iodate mixture and prediction of structure, linear optical properties of αLiZn(IO3)3 polymorph from DFT

The lithium zinc iodate polymorph α-LiZn(IO3)3 has been prepared by two different chemical routes using precipitation and heat treatment methods. The optical bandgap of αLiZn(IO3)3 was found experimentally to be 4.00 eV confirming the theoretical band gap of 3.93eV as obtained by HSE06-DFT approach. The thermal study of nano mixture lithium zinc iodate has been studied by the non-isothermal simultaneous TG and differential scanning calorimetry. The theoretical and experimental mass loss data are in good agreement for the thermal decomposition. Morphological and compositional analyses were carried out by using scanning electron microscopy and energy-dispersive X-ray measurements. The various phases were studied by powder X-ray diffraction were explored. Density functional theory was used to explore structural and optical properties of two predicted Lithium Zinc iodate polymorphs (LZI-P21), and (LZI-P63). The calculated electronic band structure and density of states show that both polymorphs have an indirect band gap an optical birefringence of 0.29 respectively.

Quantitative Analysis of the Calcium Hydroxide Content of EVA-Modified Cement Paste Based on TG-DSC in a Dual Atmosphere.

The calcium hydroxide (Ca(OH)2) content is one of the main indices of cement hydration degree. In order to accurately determine the calcium hydroxide content of ethylene and vinyl acetate (EVA) copolymer-modified cement paste, a dual atmosphere thermogravimetric method (first in an oxidizing atmosphere and then in an inert atmosphere) was used to track the mass loss and change in enthalpy by TG-DSC (simultaneous thermogravimetry and differential scanning calorimetry). The results showed that using the dual atmosphere thermogravimetric method, the source of mass loss can be distinguished. The exothermic peaks in an oxidizing atmosphere show the oxidation reactions of EVA, while the endothermic peak in an inert atmosphere is due to the pyrolysis reaction of EVA and the decomposition of the calcium hydroxide. The influence of EVA on cement hydration was investigated. The results showed that the polymer powder can be dispersed in water, forming a kind of composite membrane. The test method of dual atmosphere thermogravimetry to measure the calcium hydroxide content of polymer-modified cement pastes is more accurate and convenient than those previously applied.

Investigation on the influence of AC electric filed and KCl on the structure and gel properties of Konjac glucomannan

The influence of alternating current (AC) electric field and KCl on the structure and gel properties of Konjac Glucomannan (KGM) were studied in this work by high-performance gel permeation chromatography (HPGPC), acid-base titration, solid-state nuclear magnetic resonance (NMR), X-ray diffraction (XRD), simultaneous differential scanning calorimetry/thermo gravimetric analyzer (DSC/TGA) and a rheometer. HPGPC showed KGM was degraded by AC electric field and Acid-base titration showed that under the action of AC electric field and KCl KGM removed part of acetyl groups, which were consistent with the analysis of NMR. XRD and temperature sweep measurements respectively showed that the electrotreatment time and KCl concentration had important effects on the gel formation and its three-dimensional network. Simultaneous DSC/TGA and temperature sweep measurements both demonstrated the gel had good thermal stability.

Influence of Fluorinated Polyurethane Binder on the Agglomeration Behaviors of Aluminized Propellants.

In this study, fluorinated polyurethane (FPU) was prepared from dialcohol-terminated perfluoropolyether as a soft segment; isophorone diisocyanate (IPDI) as a curing agent; 1,2,4-butanetriol (BT) as a crosslinker; and 1,4-butanediol (BDO) as a chain extender. Fourier transform infrared spectroscopy (FTIR) and 1H NMR were used to characterize the structure of the FPU. The mechanical properties of the FPUs with different BDO and BT contents were also measured. The tensile strength and breaking elongation of the optimized FPU formula were 3.7 MPa and 412%, respectively. To find out the action mechanism of FPU on Al, FPU/Al was prepared by adding Al directly to FPU. The thermal decomposition of the FPU and FPU/Al was studied and compared by simultaneous differential scanning calorimetry-thermogravimetry-mass spectrometry (DSC-TG-MS). It was found that FPU can enhance the oxidation of Al by altering the oxide-shell properties. The combustion performance of the FPU propellant, compared with the corresponding hydroxyl-terminated polyether (HTPE)-based polyurethane (HPU) propellant, was recorded by a high-speed video camera. The FPU propellants were found to produce smaller agglomerates due to the generation of AlF3 in the combustion process. These findings show that FPU may be a useful binder for tuning the agglomeration and reducing two-phase flow losses of aluminized propellants.