Simultaneous Thermogravimetric Analysis Research Articles

Flammability and mechanical properties of composites fabricated with CaCO3-filled pine flakes and Phenol Formaldehyde resin

Flammability of wood composites has always been of a concern. To investigate whether CaCO3 particles are efficient fire-retardant fillers for wood composites, wood composites were prepared with Phenol Formaldehyde (PF) resin and pine flakes that were deposited with CaCO3 by the treatments of Na2CO3 and CaCl2. The flammable performance, Limiting Oxygen Index (LOI), simultaneous Thermogravimetric Analysis and Differential Scanning Calorimetry (TGA–DSC), mechanical properties, and water resistance of wood-flake composites deposited with CaCO3 were evaluated. Furthermore, the Scanning Electron Microscopy (SEM) was used to observe the surface morphology of the treated wood flakes, showing that CaCO3 microparticle crystals grew onto the wood flake surfaces. The increase of reactant concentrations from 0.5 M to 1.0 M resulted in an increase in LOI and improvements of the flame-retardant performance of the composites. The TGA–DTG examination showed that the decomposition peak of the treated wood flakes shifted to a lower temperature range. The TGA also demonstrated that the treatment contributed to the accumulation of char layer, which benefited the flame retardancy of the composites. The growth of energy consumed during the sample pyrolysis could be attributed to the insulation of CaCO3 and thicker char layers. After the treatment with reactants (concentration of 0.5 M), although the internal bonding (IB) slightly decreased by 8.3%, the modulus of elasticity (MOE) and the modulus of rupture (MOR) of the composites significantly increased by 182.9% and 63.5%, respectively.

Investigations of geopolymeric mixtures based on phosphate washing waste

The extraction of the phosphate ore produces a high amount of waste causing serious environmental problems. This waste, termed as phosphate washing waste, was filtered and dried at 105°C for 24h to remove the water. The dried waste was milled and then sieved in a 100μm sieve. The resulting phosphates washing waste (PWW) particles size are below 70μm. The phosphate washing waste was calcined at 700°C and 900°C. Both calcined and uncalcined waste were investigated with X-ray fluorescence (XRF), X-ray powder diffraction (DRX), Fourier transform infrared (FTIR), simultaneous differential thermal and thermogravimetric analyses (DTA-TG) and particle size analysis. This waste was activated with sodium hydroxide (NaOH) and sodium silicate in order to produce geopolymeric materials. The influence of replacing PWW by 15% of metakaolin was also study. The results show that the highest compressive strength is obtained with metakaolin. The results also showed that compressive strength decreased with the increase of NaOH concentration.

Exploring the solid-state interfacial reaction of Al/Fe2O3 nanothermites by thermal analysis

In this study, we use simultaneous differential scanning calorimetry and thermogravimetric analysis to analyze the solid-state reaction characteristics of Al/Fe2O3 nanothermites before n-Al melts. Different experimental setups for thermal analysis are compared, and the heat-release characteristics are studied on Al/Fe2O3 nanothermites in the form of powder and pellet, respectively. It is found that protection provided by mere argon flow is far from enough for thermal analysis of Al/Fe2O3 nanothermites. The experimental setup must be free of oxygen; otherwise, the determined exothermic peak is mostly the oxidation of n-Al by the residue oxygen molecules in the furnace body, due to the high reactivity and moderate accessibility of free oxygen molecules. Under proper experimental setup, it is found that besides the redox reaction between n-Al and n-Fe2O3, intermetallic reaction also occurs to form Fe4Al13. Moreover, the intermetallic reaction is more noticeable for nanothermite pellet than for nanothermite powder, and the eutectic reaction of Fe4Al13 and n-Al leads to melting peaks below 655 °C. The results indicate that instrument configuration and sample status affect the testing results to a large extent, and one should be prudent to derive reaction characteristics of nanothermites.

Thermal behavior and thermal stabilization of guanidine hydrochloride-modified acrylic fiber for preparation of low-cost carbon fiber

A commercial textile-grade acrylic fiber was modified with guanidine hydrochloride for the preparation of low-cost carbon fibers. Thermal behavior of the modified acrylic fiber was studied by simultaneous differential scanning calorimetry and thermogravimetric analysis, and the effect of guanidine hydrochloride on the thermal stabilization of acrylic fiber was investigated by Fourier transform infrared spectrometry and densimetry. The results indicated that guanidine hydrochloride could initiate the cyclization reaction of nitrile groups at lower temperature and promote the thermal stabilization of acrylic fiber. Compared with the carbon fibers prepared from the original acrylic fiber, the tensile strength and tensile modulus of the carbon fibers prepared from the modified acrylic fiber had been increased by about 72% and 34%, respectively. The guanidine hydrochloride-modified acrylic fiber was expected to be a practical low-cost carbon fiber precursor.

Kinetic Analysis of Overlapping Multistep Thermal Decomposition of 2,6-Diamino-3,5-dinitropyrazine-1-oxide (LLM-105)

Thermal decomposition kinetic behavior of energetic materials is of substantial importance for safety enhancement in manufacturing, usage, and storage. The thermal decomposition kinetic behavior of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was studied by simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC–TG). The thermal decomposition of LLM-105 is a two-step process in which the overall reaction was deconvoluted into two reaction steps for better analysis through different physical meanings consideration of the kinetic data derived from DSC and TG. Kinetic parameters of the two individual reaction steps were characterized through isoconversional and combined kinetic analysis methods. It was found that the activation energy of the first reaction step was 222.2 ± 0.5 kJ mol–1, whereas that of the second reaction step was 244.5 ± 0.5 kJ mol–1. Both steps mostly obeyed the nucleation and growth models (Avrami–Erofeev (A3)). The validity of the obtained kinetic paramete...

Structure elucidation, biological evaluation and molecular docking studies on a new organic salt: 2-Aminobenzimidazolium 5-nitro-2-hydroxybenzoate

An organic salt, 2-aminobenzimidazolium 5-nitro-2-hydroxybenzoate was synthesized and crystals were successfully grown from methanol using slow evaporation solution growth technique and recrystallization was done further to increase the purity of the crystal. The density of the grown crystals was evaluated by flotation method using carbon tetrachloride and xylene as solvents. Single crystal X-ray diffraction showed that the crystal is monoclinic system with P21/n space group and molecular structure was stabilized via three dimensional hydrogen bonding interactions. For the present crystal structure, Hirshfeld surface and fingerprint plots were drawn and analysed for the intermolecular interactions. The title compound AB5N2HB was characterized by 1H and 13C NMR spectroscopy to predict hydrogen and carbon bonded network. FT-IR and Raman spectral studies confirmed the presence of functional groups and their modes of vibrations. In the UV–Vis absorption spectrum the band at 313 nm confirmed that the proton was transferred from cation to anion. Simultaneous thermogravimetric and differential thermal analyses revealed the thermal stability and decomposition point of compound and it was stable up to 289 °C. The synthesized compound exhibited significant anti-bacterial and anti-fungal activity against different pathogens. Among them it showed good antibacterial and anti-fungal activity against Escherichia Coli and Candida albicans when compared to standard drug Penicilin G and Ketaconazole respectively. A molecular docking interaction of compound was also studied.

Al2O3/chitosan nanocomposite: Preparation, characterization and kinetic study of its thermal degradation

The 10%Al2O3/Chitosan nanocomposite (10%Al2O3/CS) was prepared and characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Brunauer, Emmett and Teller method (BET). These techniques showed the formation of 10%Al2O3/CS by the interaction between functional groups of CS such as NH2, OH and CO and Al2O3. The non-isothermal degradation process of 10%Al2O3/CS under an air atmosphere was investigated by Simultaneous ThermoGravimetric and Differential Thermal Analysis (TGA/DTA) and Differential Scanning Calorimetry (DSC) at different heating rates (β = 5, 10, 15 and 20 K/min). The kinetic parameters of thermal degradation were calculated using Kissinger-Akahira-Sunose (KAS) and Kissinger (KIS) methods, and it was found that the average values of activation energies were Ea = (110 ± 5) kJ/mol from Kissinger method, but the KIS method give three conversion domains in which Ea exhibits practically constant values, namely (0.15 – 0.30), (0.35 – 0.50) and (0.60 – 0.68) with average values of (131 ± 3) kJ/mol, (190 ± 10) kJ/mol and (71 ± 7) kJ/mol, respectively. At last, the value of range (0.15 – 0.30) was used to match the experimental and simulated Y(α) and Z(α) master plots. Indeed, it was found that the modified Sestak-Berggren f(α)=c(1−α)nαm does not correctly describe the kinetics of 10%Al2O3/CS degradation process, even if this model allowed reproducing qualitatively the Y(α) curves, giving the same maximums, αm, for each value of β in rang of α (0.15–0.3), which are consistent with the thermal degradation mechanisms of 10%Al2O3/CS. Finally, the estimated temperature of degradation is 565 K with a rate constant of 0.172 min−1.

Reactivity of magnesium borohydride – Metal hydride composites, γ-Mg(BH4)2-MHx, M = Li, Na, Mg, Ca

The reactivity and thermal decomposition of γ-Mg(BH4)2-MHx, M = Li, Na, Mg, and Ca composites has been examined with the objective of studying the hydrogen storage capability of the composites. The samples were prepared by manual grinding γ-Mg(BH4)2 with a metal hydride to obtain homogenous mixtures. In-situ synchrotron radiation powder X-ray diffraction (SR-PXD) and simultaneous thermogravimetric analysis, differential scanning calorimetry, and mass spectrometry was performed to analyse the decomposition mechanism, whereas solid-state 11B nuclear magnetic resonance spectroscopy and SR-PXD was used to investigate the decomposition products. Interestingly, substitution reactions take place between magnesium borohydride and lithium, sodium and calcium hydride forming the more stable metal borohydrides, M(BH4)x, M = Li, Na or Ca. The composite γ-Mg(BH4)2-LiH has a hydrogen release at T ∼380–420 °C, which indicates the formation of amorphous LiBH4 during decomposition. For the composites γ-Mg(BH4)2-NaH, formation of crystalline NaBH4 is observed by SR-PXD from T = 150–450 °C, and hydrogen release ascribed to NaBH4 is observed in MS data at T = 460–480 °C. γ-Mg(BH4)2-MgH2 composite decomposes as the individual constituents. β-Ca(BH4)2 is formed at T = 175–375 °C in the composites of γ-Mg(BH4)2-CaH2. Bragg diffraction from CaB6 at T > 370 °C is detected by SR-PXD for γ-Mg(BH4)2-CaH2 (1:0.5) but not for samples richer in CaH2. Release of diborane was not observed for any of the magnesium borohydride metal hydride composites.

Influence of solution composition on sprayed ZnO nanorods properties and formation process: Thermoanalytical study of the precursors

ZnO is an important inorganic material for numerous applications. Different physical and chemical methods have been applied to deposit ZnO. Spray pyrolysis method being simple, rapid and low-cost is amongst the many options and has been chosen for this study. Fabrication of ZnO nanorods crystals by chemical spray pyrolysis was performed using an acidic solution of ZnCl21 or a basic ammonia-containing solution of ZnCl22. All layers were studied using X-ray diffractometry and Scanning Electron Microscopy. The formation of ZnO nanorods from 2 appeared at 450 °C, whereas spraying acidic solution 1 yielded ZnO nanorods like morphology at 550 °C.Thermal decomposition of precursors for ZnO layers prepared by de-watering of acidic aqueous solution of ZnCl2 with pH = 3 (1) and basic solution of ZnCl2 and NH4OH with pH = 10 (2) was monitored by simultaneous thermogravimetric and differential thermal analysis (TG/DTA) in air coupled online with evolved gas analyses by Fourier transformed infrared spectroscopy (FTIR).The precursor (1) is ZnCl2 *nH2O; the precursor (2) is a mixture of (NH4)3(ZnCl4)Cl, Zn(NH3)2Cl2, NH4Cl(NH3)3 and Zn(OH)2 phases. The thermal decomposition of (1) and (2) in the temperature range of 30–700 °C consists of two steps with total mass losses of 86.2% and 93.8%, respectively. The main evolved gases from (1) are H2O and HCl, whereas the main evolved gases from (2) are H2O, NOx and NH3. Degradation of (1) and (2) is completed by 670 and 620 °C, respectively. The final decomposition product of (1) and (2) at 700 °C is ZnO.This study shows that the use of basic solutions enables to decrease the temperature of ZnO formation and the deposition temperature of ZnO nanorods layers.

Fabrication and Characterization of Multiscale PLA Structures Using Integrated Rapid Prototyping and Gas Foaming Technologies.

Multiscale structured polymers have been considered as a promising category of functional materials with unique properties. We combined rapid prototyping and gas foaming technologies to fabricate multiscale functional materials of superior mechanical and thermal insulation properties. Through scanning electron microscope based morphological characterization, formation of multiscale porous structure with nanoscale cellular pores was confirmed. Improvement in mechanical strength is attributed to rearrangement of crystals within CO2 saturated grid sample. It is also shown that a post-foaming temperature higher than the glass transition temperature deteriorates mechanical strength, providing process guidelines. Thermal decomposition of filament material sets the upper limit of temperature for 3D printed features, characterized by simultaneous differential scanning calorimetry and thermogravimetric analysis. Porosity of the fabricated 3D structured polylactic acid (PLA) foam is controllable by suitable tuning of foaming conditions. The fabricated multiscale 3D structures have potential for thermal insulation applications with lightweight and reasonable mechanical strength.

Insight into the dehydration behaviour of scandium-substituted barium titanate perovskites via simultaneous in situ neutron powder thermodiffractometry and thermogravimetric analysis

Hydration-dehydration cycles are critical to the mechanical performance of ceramic proton conductors. The development of in situ methods is desirable in order to study their structural response under conditions that mimic the operating ones. Neutron powder diffraction studies combined with simultaneous thermogravimetric analysis were performed on the hydrated forms of two members of the oxygen deficient perovskite BaTi1−xScxO3−δ series, with x = 0.5 and x = 0.7. Rietveld analyses agreed with in situ gravimetric data, allowing correlation of occupancy factors of the oxygen site to hydration levels and other structural data. Dehydration is an activated process that impacts on structural parameters and the level of Sc substitution was found to control the structural response during in situ dehydration, with higher Sc content leading to significantly greater volume contraction. This was rationalised by the chemical expansion due to hydration of oxygen vacancies within the x = 0.5 sample being anomalously small. Furthermore, the behaviour of the x = 0.5 system revealed an unexpected cell expansion during the early stages of dehydration, suggesting the hydration level may influence the thermal expansion coefficient (TEC).

Effect of the calcinations temperatures of phosphate washing waste on the structural and mechanical properties of geopolymeric mortar

The phosphate industry is facing serious environmental problems. This issue is caused by the waste after the extraction of the phosphate ore. The waste termed as phosphate washing waste (PWW) was filtered and dried at 105 °C for 24 h to remove the water. The dried PWW was milled, sieved in a 100 µm sieve and characterized by X-ray fluorescence (XRF). The resulting waste was calcined at 600, 700 and 800 °C, the calcined and uncalcined waste were investigated by X-ray powder diffraction (DRX), Fourier transform infrared (FTIR), simultaneous differential thermal and thermogravimetric analyses (DSC-TG) and scanning electron microscope (SEM). The PWW was activated with sodium hydroxide (NaOH) and sodium silicate to produce geopolymeric materials. It was found that the calcination temperature and the extra water added to the mixture to assure the good workability play an important role on the development of the system’s workability and compressive strength.

Study of thermal analysis and kinetic decomposition of polybutadiene acrylonitrile acrylic acid (PBAN)

This paper describes thermochemical properties and decomposition characteristics of polybutadiene acrylonitrile acrylic acid (PBAN). The thermal behavior of PBAN samples containing various amounts of nitrile groups was determined by simultaneous thermogravimetric analysis and differential scanning calorimetry (TG/DSC). The results indicate that nitrile content in PBAN affects thermal behavior markedly. The influence of heating rate on the DSC behavior of the PBAN was investigated, while thermal decomposition of these compounds followed the first-order law. The kinetic parameters such as activation energy and frequency factor for these compounds were obtained from the DSC data by non-isothermal methods. Also the impact of different ratio of nitrile content in PBAN on glass transition temperature (Tg) of this terpolymer was measured.

Thermal Study of Polyols for the Technological Application as Plasticizers in Food Industry.

In this work is presented the complete thermal analysis of polyols by direct methods such as simultaneous thermogravimetric and differential thermal analyzer (TGA-DTA), differential scanning calorimetry (DSC), modulated DSC (MDSC), and supercooling MDSC. The different thermal events in the temperature range of 113–553 K were identified for glycerol (GL), ethylene glycol (EG), and propylene glycol (PG). Boiling temperature (TB) decreased as GL > EG > PG, but increased with the heating rate. GL showed a complex thermal event at 191–199 K, identified as the glass transition temperature (Tg) and devitrification temperature (Tdv), and a liquid–liquid transition (TL-L) at 215–221 K was identified as the supercooling temperature. EG showed several thermal events such as Tg and Tdv at 154 K, crystallization temperature (Tc) at 175 K, and melting temperature (Tm) at 255 K. PG also showed a complex thermal event (Tg and Tdv) at 167 K, a second devitrification at 193 K, and TL-L at 245 K. For PG, crystallization was not observed, indicating that, during the cooling, the liquid remained as an amorphous solid.

Investigation of thermoplastic powder synergizing polymorphic foam to inhibit coal oxidation at low temperature

An innovative method involving thermoplastic powder synergizing polymorphic foam (TPPF) is proposed to inhibit the self-heating of coal. The TPPF is synthesized by polycaprolactone, polyethylene, sodium silicate solution, sodium dodecyl sulfate, organic acid and water. It exhibits excellent performance in improving the thermal stability of coal, suppressing the coal self-heating process and extinguishing coal fire. This study includes the preparation process of the TPPF, and differential scanning calorimetry measurements, and a polarizing microscope linked to a thermal station, and simultaneous differential thermogravimetric scanning calorimetric analyzer linked to a mass spectrometer and electron paramagnetic resonance. A preparation device of the TPPF with gas as the sole power source and an optimal working pressure of 0.45 MPa was designed. The TPPF could absorb the heat generated by coal self-heating and was fused simultaneously into a colloid to wrap the coal surface to prevent oxygen ingress, resulting in that the initial reaction of carbon free radicals and methyne reacting with oxygen was controlled; the colloid could maintain extra water vapor to form a multilayer at the surface of coal pores and increase the diffusion resistance for the access of oxygen, leading to the peroxygen content decrease; it could also prevent bridge bonds and branched chain breakage to generate new active hydroxyl and alkyl groups, and consume alkoxy and peroxy radicals generated in the coal low-temperature oxidation process by the hydrogen ions. Therefore, The TPPF could decrease the free radicals concentration of coal and cut off the chain reactions of coal self-heating. The TPPT also decomposed large amounts of water, carbon dioxide and a weight of 80.8% non-flammable residue, mainly consisting of Na2CO3 and SiO2, to choke coal self-heating.

Kinetic Study and Thermal Decomposition Behavior of Magnesium-Sodium Nitrate Based on Hydroxyl-Terminated Polybutadiene

This paper has been utilizing the simultaneous ThermoGravimetric analysis and Differential Scanning Calorimetry (TG–DSC) to investigate the thermal decomposition of magnesium-sodium nitrate pyrotechnic composition based HTPB resin. The thermal behaviors of different samples with various fuel-oxidizer ratio contents were determined. Decomposition kinetic was investigated by evaluating the influence of DSC heating rate (4, 7, 10, 13 oC/min) on the behavior of the illumination flares. The results as expected showed that the decomposition temperature of the illumination flares decreases with the increase in the DSC heating rate, while thermal decomposition of the sample followed the first-order law. Furthermore, Magnesium-sodium nitrate illumination flares with HTPB resin have been studied for luminous efficiency by varying fuel/oxidizer ratio. The kinetic and thermodynamic parameters of the illumination flares decomposition under ambient pressure were obtained from the resulted DSC data via non-isothermal methods proposed by ASTM E698 and Flynn-Wall-Ozawa. Also, the critical temperature of ignition temperature was estimated at about 455 oC.

Low-Temperature Oxidation of Fine UO2 Powders: Thermochemistry and Kinetics.

The thermochemical behavior of low-temperature oxidation in fine UO2 powders has been investigated by simultaneous thermogravimetric analysis and differential scanning calorimetry. The evaluation of the thermochemical and kinetic data reveals a complex interplay between different mechanisms. The initial reaction concerns the rapid chemisorption of oxygen gas onto the surface of UO2 grains, having an activation energy of only 13.1 ± 0.6 kJ mol-1. The subsequent oxidation at temperatures between 40 and 100 °C occurs first at the surface via a field-assisted mechanism, which progresses via domain growth into the bulk. At more elevated temperatures, thermally activated diffusion becomes the dominant mechanism.

English

The search for sources of animal feed has been well-regarded for farmers. In spite of this, the objective of this study was to show the thermal, physical and chemical properties of earthworms flour from Eisenia andrei for supplementary food for animals. The species was studied by simultaneous thermogravimetric analysis, differential scanning calorimetry, combustion calorimetry, moisture, ash, fat, protein, carbohydrate and fibre analysis. The samples were dried, ground, screened and stored in suitable vials. After the analysis of physical and chemical characterization, it was possible to verify that E. andrei flour presents higher calorific power and levels of protein, fiber, carbohydrate, essential metals and low fat. It can be a promising product as an ideal alternative protein source for better growth performance of animals. Key words: Earthworm, vermicomposting, physical and chemical analysis.

Microporosity and CO₂ Capture Properties of Amorphous Silicon Oxynitride Derived from Novel Polyalkoxysilsesquiazanes.

Polyalkoxysilsesquiazanes ([ROSi(NH)1.5]n, ROSZ, R = Et, nPr, iPr, nBu, sBu, nHex, sHex, cHex, decahydronaphthyl (DHNp)) were synthesized by ammonolysis at −78 °C of alkoxytrichlorosilane (ROSiCl3), which was isolated by distillation as a reaction product of SiCl4 and ROH. The simultaneous thermogravimetric and mass spectrometry analyses of the ROSZs under helium revealed a common decomposition reaction, the cleavage of the oxygen–carbon bond of the RO group to evolve alkene as a main gaseous species formed in-situ, leading to the formation of microporous amorphous Si–O–N at 550 °C to 800 °C. The microporosity in terms of the peak of the pore size distribution curve located within the micropore size range (<2 nm) and the total micropore volume, as well as the specific surface area (SSA) of the Si–O–N, increased consistently with the molecular size estimated for the alkene formed in-situ during the pyrolysis. The CO2 capture capacity at 0 °C of the Si–O–N material increased consistently with its SSA, and an excellent CO2 capture capacity of 3.9 mmol·g−1 at 0 °C and CO2 1 atm was achieved for the Si–O–N derived from DHNpOSZ having an SSA of 750 m2·g−1. The CO2 capture properties were further discussed based on their temperature dependency, and a surface functional group of the Si–O–N formed in-situ during the polymer/ceramics thermal conversion.

Experimental and Theoretical Investigation of Structures, Stoichiometric Diversity, and Bench Stability of Cocrystals with a Volatile Halogen Bond Donor

We present a combined experimental and theoretical study of the structures and bench stability of halogen-bonded cocrystals involving the volatile halogen bond donor octafluoro-1,4-diiodobutane, with phenazine and acridine as acceptors. Cocrystallization experiments using mechanochemistry and solution crystallization revealed three chemically and structurally distinct cocrystals. Whereas only one cocrystal form has been observed with acridine, cocrystallization with phenazine led to two stoichiometrically different cocrystals, in which phenazine employs either one or two nitrogen atoms per molecule as halogen bond acceptor sites. Cocrystal stability was evaluated experimentally by simultaneous thermogravimetric analysis and differential thermal analysis or differential scanning calorimetry, real-time powder X-ray diffraction monitoring of cocrystals upon storage in open air, and theoretically by using dispersion-corrected periodic density functional theory. The use of real-time powder X-ray diffraction en...