Showing papers on "Thermal decomposition published in 2014"
TL;DR: The results showed that higher extractive contents associated with lower crystallinity and lower cellulose crystallite size can accelerate the degradation process and reduce the thermal stability of the lignocellulosic fibers studied.
Abstract: In this work, the relationship between cellulose crystallinity, the influence of extractive content on lignocellulosic fiber degradation, the correlation between chemical composition and the physical properties of ten types of natural fibers were investigated by FTIR spectroscopy, X-ray diffraction and thermogravimetry techniques. The results showed that higher extractive contents associated with lower crystallinity and lower cellulose crystallite size can accelerate the degradation process and reduce the thermal stability of the lignocellulosic fibers studied. On the other hand, the thermal decomposition of natural fibers is shifted to higher temperatures with increasing the cellulose crystallinity and crystallite size. These results indicated that the cellulose crystallite size affects the thermal degradation temperature of natural fibers. This study showed that through the methods used, previous information about the structure and properties of lignocellulosic fibers can be obtained before use in composite formulations.
664 citations
TL;DR: This systematic study provides insight into the rational design of NMC-based cathode materials with a desired balance between thermal stability and high energy density.
Abstract: Thermal stability of charged LiNixMnyCozO2 (NMC, with x + y + z = 1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time-resolved X-ray diffraction and mass spectroscopy (TR-XRD/MS) techniques upon heating up to 600 °C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and the larger amount of oxygen release. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability, comparable to the low-nickel-content materials (e.g., NMC333 and NMC433), while having a high capacity close to the high-nickel-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes ...
653 citations
TL;DR: In this article, the thermal stability of 66 ionic liquids (ILs) was investigated using the thermogravimetric analysis (TGA) method, and the thermal decomposition kinetics of ILs were analyzed using pseudo-zero-order rate expression and their activation energy was obtained.
Abstract: The thermal stabilities of 66 ionic liquids (ILs) were investigated using the thermogravimetric analysis (TGA) method. Isothermal TGA studies on the ILs showed that ILs exhibit decomposition at temperatures lower than the onset decomposition temperature (Tonset), which is determined from ramped temperature TGA experiments. Thermal decomposition kinetics of ILs was analyzed using pseudo-zero-order rate expression and their activation energy was obtained. Parameter T0.01/10h, the temperature at which 1% mass loss occurs in 10 h, was used to evaluate the long-term thermal stability of ILs. The thermal stability of the ILs was classified to five levels according to Tonset. The ILs thermal stability is dependent on the structure of ILs, i.e., cation modification, cation and anion type. The correlations between the stability and the hydrophilicity of ILs were discussed. Finally, the thermal stabilities of acetate-based ILs, amino acid ILs, and dicyanamide ILs were analyzed.
556 citations
TL;DR: This article used commercially available xylan as a model compound representing hemicelluloses, not taking in account the heterogeneous nature of that group of carbohydrate groups, and used it for decomposition of biomass.
306 citations
TL;DR: In this paper, a modified thermal decomposition sol-gel method with low-cost and low-toxicity for CZTS thin film preparation is presented, and the detailed formation mechanism of the thin film is investigated to obtain an optimized process.
Abstract: Earth-abundant Cu2ZnSnS4 (CZTS) has been confirmed as a promising semiconductor material for thin film solar cells. To meet the requirements of high-efficiency and low-cost for photovoltaic technologies, a modified thermal decomposition sol–gel method with low-cost and low-toxicity for CZTS thin film preparation is presented, and the detailed formation mechanism of the thin film is investigated to obtain an optimized process. By introducing non-aqueous thiourea–metal–oxygen sol–gel processing, as well as applying extrinsic dopants and chemical etching, high-quality and phase-controlled CZTS thin films with homogeneous elemental distribution and a low impurity content have been synthesized. Based on the modified sol–gel method, solar cells with a structure of Ni:Al/ZAO/i-ZnO/CdS/CZTS/Mo/glass have been fabricated, and a power conversion efficiency of 5.10% is obtained, indicating its potential for high-throughput and high power conversion efficiency photovoltaic devices.
242 citations
TL;DR: It is found that MACl functions as a glue or soft template to control the initial formation of a solid solution with the main MAPbI2Br precursor components (i.e., PbI 2 and MABr) and strongly affects the device characteristics.
Abstract: Hybrid organometallic halide perovskite CH3NH3PbI2Br (or MAPbI2Br) nanosheets with a 1.8 eV band gap were prepared via a thermal decomposition process from a precursor containing PbI2, MABr, and MACl. The planar solar cell based on the compact layer of MAPbI2Br nanosheets exhibited 10% efficiency and a single-wavelength conversion efficiency of up to 86%. The crystal phase, optical absorption, film morphology, and thermogravimetric analysis studies indicate that the thermal decomposition process strongly depends on the composition of precursors. We find that MACl functions as a glue or soft template to control the initial formation of a solid solution with the main MAPbI2Br precursor components (i.e., PbI2 and MABr). The subsequent thermal decomposition process controls the morphology/surface coverage of perovskite films on the planar substrate and strongly affects the device characteristics.
213 citations
TL;DR: The pyrolysis and co-pyrolytic behaviors of polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) under N2 atmosphere were analyzed by Thermal gravimetric/Fourier transform infrared (TG/FTIR) to investigate the interaction of the plastic blends during the thermal decomposition process.
175 citations
TL;DR: In this article, the photo-catalytic decomposition mechanism is discussed through the detection of hydroxyl radical (OH ) by terephthalic acid photo-luminescence probing technique.
159 citations
TL;DR: In this article, CaO nanoparticles were prepared via direct thermal decomposition method using Ca(OH) 2 as a wet chemically synthesized precursor, which can be used for production of CaO nano-particles on large scale as a cheap and convenient way, without using any surfactant, organic medium or complicated equipment.
151 citations
TL;DR: In this paper, the thermal behavior of plastics and their blends with biomass (bamboo, empty fruit bunch and sawdust) was investigated and the results of the analyses suggested that the co-pyrolysis characteristics of the blends are quite different to the combination of the individual materials and therefore the possible synergic effect points to the existence of chemical interactions between the plastic and biomass fractions.
149 citations
TL;DR: The results show that the reaction mechanism of whole process can be kinetically characterized by two successive reactions, a diffusion reaction followed by a third order rate equation, and the results derived are useful for development and optimization of biomass thermochemical conversion systems.
TL;DR: Copper nanoparticles were synthesized by thermal decomposition using copper chloride, sodiumoleate, and phenyl ether as solvent agents as discussed by the authors, and the formation of nanoparticles was evidenced by the X-ray diffraction and transmission electron microscopy.
Abstract: Copper nanoparticles were synthesized by thermal decomposition using copper chloride, sodiumoleate, and phenyl ether as solvent agents The formation of nanoparticles was evidenced by the X-ray diffraction and transmission electron microscopy The peaks in the XRD pattern correspond to the standard values of the face centered cubic (fcc) structure of metallic copper and no peaks of other impurity crystalline phases were detected TEM analysis showed spherical nanoparticles with sizes in the range of 4 to 18 nm The antibacterial properties of copper nanoparticles were evaluated in vitro against strains of Staphylococcus aureus and Pseudomonas aeruginosa The antibacterial activity of copper nanoparticles synthesized by thermal decomposition showed significant inhibitory effect against these highly multidrug-resistant bacterial strains
TL;DR: In this article, a new MoS2/CoOOH hybrid material was successfully synthesized by a facile wet chemical method, and its structure was confirmed by X-ray diffraction and Raman spectroscopy.
Abstract: In this work, a new MoS2/CoOOH hybrid material was successfully synthesized by a facile wet chemical method, and its structure was confirmed by X-ray diffraction and Raman spectroscopy. A morphological study showed that, due to the different sizes of the two components, the resulting MoS2/CoOOH hybrid displayed a disordered structure in which large MoS2 sheets had many independent and separate CoOOH nanoplatelets on the surface. The catalytic oxidation effect of MoS2/CoOOH hybrids on the thermal decomposition of epoxy resin was studied by thermogravimetric analysis-infrared spectrometry. It was found that the amount of organic volatiles of epoxy resin significantly decreased and non-flammable CO2 was generated after incorporating MoS2/CoOOH hybrids, which implied the reduced toxicity of the volatiles and obvious smoke suppression. Meanwhile, the incorporation of MoS2/CoOOH hybrids also resulted in a remarkable increase in the char residue of the epoxy composite, indicating the efficient catalytic carbonization of MoS2/CoOOH hybrids. Based on the X-ray diffraction and Fourier transform infrared results of the char residue, the possible mechanism of the reduced fire hazards and high char formation of the epoxy composites was proposed as the combination of the adsorption and synergistic catalytic effect of the MoS2/CoOOH catalyst, which would provide promising applications in the development of fire safety polymer materials.
TL;DR: In this article, solid-state thermal decomposition route was applied for synthesis of Ag and Ag2O nanoparticles of new precursor [Ag(Hsal)] for the first time, and the results showed that pure cubic Ag and hexagonal Ag 2O could be obtained after annealing at 400°C for 3h in an Ar gas and in an air, respectively.
TL;DR: Thermal and physicochemical characterization results of corncob and its derived biochars were analyzed and differentiated from sawdust and cornstalk and the weight active energy of the CC was the lowest value compared to those of CS and SD.
TL;DR: This study elucidates the origin of the difference between the activation energies in the gas phase and the condensed phase of TNT and identifies the corresponding universal principle and the different reactivities of nitro-based organic explosives are rationalized as an interplay between uni- and bimolecular processes.
Abstract: Activation energy for the decomposition of explosives is a crucial parameter of performance. The dramatic suppression of activation energy in condensed phase decomposition of nitroaromatic explosives has been an unresolved issue for over a decade. We rationalize the reduction in activation energy as a result of a mechanistic change from unimolecular decomposition in the gas phase to a series of radical bimolecular reactions in the condensed phase. This is in contrast to other classes of explosives, such as nitramines and nitrate esters, whose decomposition proceeds via unimolecular reactions both in the gas and in the condensed phase. The thermal decomposition of a model nitroaromatic explosive, 2,4,6-trinitrotoluene (TNT), is presented as a prime example. Electronic structure and reactive molecular dynamics (ReaxFF-lg) calculations enable to directly probe the condensed phase chemistry under extreme conditions of temperature and pressure, identifying the key bimolecular radical reactions responsible for ...
TL;DR: In this article, β-cyclodextrin-modified CNC@Fe3O4@SiO2 superparamagnetic nanorods for the removal of two model compounds were synthesized.
Abstract: This paper reports on the synthesis of β-cyclodextrin-modified CNC@Fe3O4@SiO2 superparamagnetic nanorods for the removal of two model compounds: procaine hydrochloride and imipramine hydrochloride. During the synthetic process, sustainable natural materials and low-cost chemicals were used, and mild reaction conditions were adopted. TEM and SEM images indicated good dispersion of Fe3O4 nanoparticles with uniform silica coating on CNCs. The thickness of the silica coating was controlled by manipulating the amounts of precursor solution used. TGA data confirmed that the silica coating significantly enhanced the thermal stability of CNCs. The onset decomposition temperature of CNC@Fe3O4@SiO2 hybrids increased by 60 °C compared to pure CNCs. XRD, EDS, and FT-IR analyses confirmed the structure of CNC@Fe3O4@SiO2 and the successful grafting of β-cyclodextrin. The CNC@Fe3O4@SiO2@β-CD hybrids displayed good adsorption toward the model pharmaceutical residues: procaine hydrochloride and imipramine hydrochloride.
TL;DR: In this paper, the performance of the synthesized material on the thermal decomposition of ammonium perchlorate (AP) was investigated creatively by differential scanning calorimetry (DSC).
TL;DR: In this article, the ReaxFF reactive force field was used to perform pyrolysis simulations on a large-scale (>50,000 atoms) molecular model for Illinois no. 6 coal.
TL;DR: In this article, the tensile properties of composites of poly(lactic acid) (PLA) containing up to 40% of kenaf fiber and up to 10% of thymol were studied to evaluate mechanical and thermal properties.
TL;DR: A simple oleylamine-based thermal decomposition process using different time steps for precursor injection was used to obtain bimetallic Ag-Cu nanoparticles with a narrow size distribution as discussed by the authors.
Abstract: A simple oleylamine-based thermal decomposition process using different time steps for precursor injection was used to obtain bimetallic Ag–Cu nanoparticles with a narrow size distribution. Experim...
TL;DR: In this paper, a binuclear zinc (II) curcumin (ZnO) nanoparticles were generated by thermal decomposition of a single source precursor with a maximum weight loss rate of 14%/min.
TL;DR: In this article, an aryl boron-containing phenolic resin (PR) exhibiting an extremely high thermal decomposition temperature and char yield was formed by reacting phenylboronic acid (PBA) with PR.
TL;DR: In this article, a potential compatibilizer for PLA/BF composites, PLA-g-glycidyl methacrylate (GMA), was synthesized by grafting GMA onto PLA using benzoyl peroxide and tert-butyl peroxy benzoate as initiators.
TL;DR: In this article, bimetallic Ni-Fe, Ni-Co and Fe-Co supported on MgO catalysts with a total metals content of 50wt.% were evaluated for decomposition of methane to CO/CO2 free hydrogen and carbon nanomaterials.
TL;DR: The potential energy surfaces for the pyrolysis relevant reactions of the biofuel candidate 2-methylfuran have been characterized using quantum chemical methods using Canonical transition state theory and Rice-Ramsperger-Kassel-Marcus theory to determine the high-pressure limiting kinetics of elementary reactions.
Abstract: Due to the rapidly growing interest in the use of biomass derived furanic compounds as potential platform chemicals and fossil fuel replacements, there is a simultaneous need to understand the pyrolysis and combustion properties of such molecules. To this end, the potential energy surfaces for the pyrolysis relevant reactions of the biofuel candidate 2-methylfuran have been characterized using quantum chemical methods (CBS-QB3, CBS-APNO and G3). Canonical transition state theory is employed to determine the high-pressure limiting kinetics, k(T), of elementary reactions. Rice–Ramsperger–Kassel–Marcus theory with an energy grained master equation is used to compute pressure-dependent rate constants, k(T,p), and product branching fractions for the multiple-well, multiple-channel reaction pathways which typify the pyrolysis reactions of the title species. The unimolecular decomposition of 2-methylfuran is shown to proceed via hydrogen atom transfer reactions through singlet carbene intermediates which readily undergo ring opening to form collisionally stabilised acyclic C5H6O isomers before further decomposition to C1–C4 species. Rate constants for abstraction by the hydrogen atom and methyl radical are reported, with abstraction from the alkyl side chain calculated to dominate. The fate of the primary abstraction product, 2-furanylmethyl radical, is shown to be thermal decomposition to the n-butadienyl radical and carbon monoxide through a series of ring opening and hydrogen atom transfer reactions. The dominant bimolecular products of hydrogen atom addition reactions are found to be furan and methyl radical, 1-butene-1-yl radical and carbon monoxide and vinyl ketene and methyl radical. A kinetic mechanism is assembled with computer simulations in good agreement with shock tube speciation profiles taken from the literature. The kinetic mechanism developed herein can be used in future chemical kinetic modelling studies on the pyrolysis and oxidation of 2-methylfuran, or the larger molecular structures for which it is a known pyrolysis/combustion intermediate (e.g. cellulose, coals, 2,5-dimethylfuran).
TL;DR: In this paper, a kinetic reaction model for thermal decomposition of urea is presented, which matches all performed thermogravimetric analyses and is also able to reproduce changes in measurement conditions, such as differences in crucibles geometry or variations of the initial sample mass.
TL;DR: In this paper, the thermal decomposition behavior of three common biowastes in Taiwan (cedar sawdust, coffee bean residue, and rice straw) upon fast pyrolysis was studied.
TL;DR: In this paper, TGA and DSC data were used to study the changes occurring during, and differences between materials after, the annealing step of mixed-halide methylammonium lead halide perovskites.
Abstract: Thermal analysis (TGA and DSC), coupled with evolved gas FTIR spectroscopy, has been used to study the changes occurring during, and differences between materials after, the annealing step of mixed-halide methylammonium lead halide perovskites. This is important because, to date, the material is the most efficient light harvester in highly efficient, 3rd generation perovskite photovoltaic devices, and processing plays a significant role in device performance. TGA-FTIR data show only solvent evolution during the annealing step, whilst post-annealing analysis shows that the resulting material still contains a significant amount of residual solvent; however, efficient DMF removal was possible using a silica gel desiccant for a period of 3 days. The data also show that methylammonium halide decomposition does not occur until temperatures well above those used for perovskite processing, suggesting that this is not a significant issue for device manufacture. The absence of a well-defined, reversible tetragonal – cubic phase change around 55 °C in the DSC data of the annealed material, and the presence of HCl in evolved gas analysed following thermal decomposition, demonstrates that CH3NH3I3−xClx does retain some Cl after annealing and does not simply form stoichiometric CH3NH3PbI3 as has been suggested by some workers.
TL;DR: Thermal decompositions of three components of biomass were studied using nonisothermal thermogravimetric analysis (TGA) under both oxidative and inert atmospheres and showed that the presence of CO₂ enhanced the thermal decomposition behaviors of three component in high temperature range, but made little difference in low temperature range.