Thermal Decomposition Activation Research Articles

Facile synthesis of CuO nanobricks for high combustion characteristics with nanoaluminum and catalytic thermal decomposition of lithium perchlorate

Reactive metal/metal-oxide based nanoenergetic materials find tremendous applications in propellants, explosives, and pyrotechnics. This paper reports on the synthesis of CuO nanobricks (CuOnb) using simple and rapid solid-state methods and investigation of the combustion reactivity (combustion propagation speed, peak pressure and pressurization rate) of as-synthesized copper oxide nanobricks with nano-aluminum and catalytic activity of copper oxide nanobricks in thermal decomposition of lithium perchlorate (LiClO4). The X-ray diffractometry (XRD) and transmission electron microscopy revealed the fabrication of CuO nanobricks (length of sub-150 nm with square cross-section of size of sub-25 nm). The CuOnb based nano-aluminum energetic composites (Al/CuOnb) exhibited excellent combustion characteristics with combustion propagation speed of 1,760 ± 25 m/s, peak pressure of 61.2 MPa, pressurization rate of 1.02 MPa/µs and heat of reaction of 750 J/g respectively. The copper oxide nanobricks expressed high catalytic activity in thermal decomposition of LiClO4 by accelerating the thermal decomposition to start and accomplish at lower temperature than the pure lithium perchlorate.

MnCo2O4 nanoparticles with excellent catalytic activity in thermal decomposition of ammonium perchlorate

MnCo2O4 spinel nanoparticles (NPs) have been prepared using Aloe vera gel solution. The characterization of prepared spinel was performed applying Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron spectroscope, scanning electron microscope and dynamic light scattering. The results manifested that the prepared nanoparticles were mainly spherical plus minor agglomeration with average size distribution between 35 and 60 nm. The catalytic activity of the prepared nanoparticles upon thermal degradation of ammonium perchlorate (AP) was evaluated applying differential scanning calorimetry and thermogravimetry instruments. MnCo2O4 nanoparticles increased the released heat of AP from 450 to 1480 J g−1 and decreased the decomposition temperature from 420 to 293 °C. The kinetic parameters obtained from Kissinger methods showed that the activation energy of AP thermal decomposition in the presence of MnCo2O4 NPs considerably decreased. Also, a mechanism has been proposed in the presence of catalyst for the process of thermal decomposition of AP.

Thermogravimetric analysis and structure change of lime-pretreated Spartina alterniflora

ABSTRACTThe thermal behavior and structure change of Spartina alterniflora pretreated with lime were investigated with raw and water-soaked samples for comparisons. Pretreatment significantly changed thermal decomposition behavior and activation energy. The activation energy of S. alterniflora ranged from 100.7 to 128 kJ/mol at the main decomposition stage. FTIR and solid-state 13C NMR analyses revealed that pretreatment disrupted the carboxyl carbons attached to the lignin side chain. Compared with water soaking, lime pretreatment resulted in more modifications of structure and composition. Furthermore, structure breakage and composition removal change the pyrolysis characteristics of pretreated samples.

Synthesis, characterization, migration and catalytic effects of energetic ionic ferrocene compounds on thermal decomposition of main components of solid propellants

Sixteen new energetic ionic ferrocene compounds, [FcCH2N(CH3)2(CnH2n+1]+X− (Fc=ferrocenyl; X−=nitrate or picrate anion; n=3–10), were synthesized in high yields and characterized by 1H NMR, 13C NMR, UV–Vis, elementary analysis, TG and DSC methods. All the compounds show high thermal stability. Cyclic voltammetry investigations revealed that the ionic compounds exhibit redox waves for ferrocenyl groups and are considered as irreversible redox systems. Migration studies disclosed that their migration tendency increases with elongation of alkyl chain length in the cations of the compounds, and much slower than that of neutral n-butylferrocene (NBF). The sensitivities tests towards impact and friction revealed that all picrates are sensitive compounds, while the nitrates are less sensitive analogs. Their catalytic performances for thermal degradation of main components of solid propellants such as ammonium perchlorate (AP), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), 1,2,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) and hydroxyl-terminated polybutadiene (HTPB) as well as 1:1 mixture of HTPB and AP, were evaluated by DSC and/or TG techniques. All the ionic compounds can efficiently catalyze the thermal degradation of AP, HTPB and their 1:1 mixture. Compounds 1–8, 11 and 16 exhibit catalytic activity in thermal decomposition of RDX. None of them display distinct catalytic effect on the thermal degradation of HMX. These low-migration ferrocene derivatives may be used as alternatives to NBF in HTPB/AP composite solid propellants.

Thermal decomposition and biological activity studies of some transition metal complexes derived from mixed ligands sparfloxacin and glycine

The synthetic method of novel ternary M(II)/(III)/(IV) complexes, with fluoroquinolone drug sparfloxacin (HSFX) and glycine (HGly) containing nitrogen and oxygen donor ligand have been synthesized and characterized. The prepared complexes fall into stoichiometric formulae of [M(SFX)(Gly)(H2O)2]Cl (M = Cr(III) and Fe(III), [M(SFX)(Gly)(H2O)2] (M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and UO2(II) and [Th(SFX)(Gly)(H2O)2]Cl2. The chelate rings are six-membered and six coordinate with 1:1:1 [M]:[SFX]:[Gly]. The important bands in the IR Spectra and main 1H NMR signals are tentatively assigned and discussed in relation to the predicted molecular structure. The IR data of the HSFX and HGly ligands suggested the existing of a bidentate binding involving carboxylate O and carbonyl O for HSFX ligand and amino N and carboxylate O atoms for HGly ligand. The coordination geometries and electronic structures are determined from the diffused reflectance spectra and magnetic moment measurements. The complexes exist in octahedral form. The complexes decomposed in four to six steps within the temperature range 30–1,000 °C with metal oxides as residues of decomposition. The decomposition steps are accompanied by endothermic or exothermic peaks in the DTA. The HSFX drug, HGly and metal complexes have been screened for their in vitro antibacterial activities against Staphylococcus aureus and Escherichia coli, and antifungal activities against Aspergillus niger and Candida albicans by MIC method. The metal complexes were found to have higher antimicrobial activity than the HSFX drug and HGly ligand and their activity are comparable with the antibacterial and antifungal standards.

Nitrated graphene oxide and its catalytic activity in thermal decomposition of ammonium perchlorate

Nitrated graphene oxide (NGO) was synthesized by nitrifying homemade GO with nitro-sulfuric acid. Fourier transform infrared spectroscopy (FTIR), laser Raman spectroscopy, CP/MAS 13C NMR spectra and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure of NGO. The thickness and the compositions of GO and NGO were analyzed by atomic force microscopy (AFM) and elemental analysis (EA), respectively. The catalytic effect of the NGO for the thermal decomposition of ammonium perchlorate (AP) was investigated by differential scanning calorimetry (DSC). Adding 10% of NGO to AP decreases the decomposition temperature by 106°C and increases the apparent decomposition heat from 875 to 3236J/g.

Synthesis, Spectral and Thermal Studies on Cobalt(II), Copper(II), Nickel(II) and Zinc(II) Chelates with p-tolylsalicylaldimine and Some Amino Acids

New cobalt(II), copper(II), nickel(II) and zinc(II) complexes of the p-tolyIsalicylaIdimine Schiff base (sal-TH) and some amino acids have been prepared. The complexes have the general formula [M(sal-T)(aa)].nH2O where M = Co(II), Cu(II), Ni(II) and Zn(II); sal-T = monoanion of the Schiff base p-tolylsalicylaldimine; aa = monoanion of the amino acids phenylalanine (Phala), tyrosine (tyr) or methionine (met); n = 0 for M = Co(II), Cu(II) or Ni(II) and n = 2 for M = Zn(II). The complexes have been characterized and studied by elemental analyses, conductivity, IR and UV-V1S spectroscopy as well as thermogravimetry. The Cu(II) complexes have been proposed to possess a square-planar structure while the Co(II), Ni(II) and Zn(II) complexes have an octahedral structure attained by mutual intermolecular interactions among the adjacent mixed amino acid-Schiff base molecules. The thermal decomposition reaction order and activation energy have been computed by means of the Coats-Redfern and Horowitz-Metzger methods. The biological activity of selected complexes against some bacteria and fungi have been tested.