The thermal decomposition behavior of RDX-base propellants

In this paper, the thermal decomposition of cyclotrimethylenetri-nitramine (RDX)-base propellants involving many components has been investigated by differential scanning calorimeter (DSC). The decomposition characters at different heating rates and the activation energies are determined by DSC measurement. The results show that the decomposition of RDX is accelerated obviously during the decomposition of nitroglycerin (NG). Though the content of dibutyl-benzene-dicarbonate (DBP) ingredient in the propellants is less, it has a remarkable effect on the initial decomposition temperature of the propellants. The azido-nitromine compound (DIANP) brings about the shift of the peak of decomposition of RDX and nitrocellulose (NC) to lower temperature due to its liquefying or dissolving.     

Synthesis,characterization and acceptor behavior of n-butyltin(IV)-2,4-dimethylphenoxides

The n-butyltin(IV) complexes, n-BuSnCl_3?x(OC₆H₃(CH₃)₂-2,4) _x (where x?=?1–3), have been synthesized in quantitative yields by employing the reaction of n-BuSnCl₃ with 2,4-dimethylphenol and sodium acetate in methanol and benzene solvents at room temperature. The complexes have been characterized by elemental analysis, molar conductivity, and FT-IR, ¹H- and ¹³C-NMR, and mass spectral studies. Thermal behavior has been studied by TG–DTA techniques. Lewis acid character of n-BuSn(OC₆H₃(CH₃)₂-2,4)₃ has been investigated by reacting it with bases such as 2,2′-bipyridine and 1,10-phenanthroline (B), Ph₃PO and Ph₃AsO (LO) and phosphorus and arsenic donors Ph₃P, Ph₃As, and As(SPh)₃ (L). The formation of 1?:?1 and 1?:?2 (metal?:?base) coordination compounds [n-BuSn(OC₆H₃(CH₃)₂-2,4)₃·B] and n-[BuSn(OC₆H₃(CH₃)₂-2,4)₃·2LO/2L] has been authenticated by physicochemical and IR spectral studies. In order to infer the biological relevance of newly synthesized complexes, the antibacterial activity has been assayed against six bacterial strains Klebsiella pneumoniae, Staphylococcus epidermidis, Staphylococcus aureus, Salmonella typhi, Salmonella paratyphi, and Escherichia coli. In this study, n-BuSnCl₂(OC₆H₃(CH₃)₂-2,4) and n-BuSnCl(OC₆H₃(CH₃)₂-2,4)₂ showed better activity than precursor and ligand, while n-BuSn(OC₆H₃(CH₃)₂-2,4)₃ did not exhibit improved activity.     

Synthesis of a bio-based plasticizer from oleic acid and its evaluation in PVC formulations

The bio-based plasticizers have been extensively developed due to their high compatibility and low toxicity. In this study, the bio-based plasticizers of methyl 10-(2-methoxy-2-oxoethansulfonyl) octadecanoate (MDA) and ethyl 10-(2-ethoxy-2-oxoethanesulfonyl) octadecanoate (EDA) were synthesized from the oleic acid and thioglycolic acid and characterized by ¹HNMR and FT-IR. The prepared materials were applied as plasticizers in Poly(vinyl chloride) (PVC) and their properties were compared with the commercial plasticizer, Bis(2-ethylhexyl) phthalate (DOP). The viscosities of prepared plastisols from novel designed plasticizers were lower than DOP. The results of mechanical properties showed that the synthesized plasticizers of MDA and EDA have the ability of plasticizing effects similar to DOP on PVC. Thermogravimetric analysis (TGA) indicated that both MDA and EDA have higher thermal stability than DOP. Two polar ester as well as polar sulfone groups in the chemical structure of MDA and EDA led to lower migration, volatility and exudation than DOP.     

Synthesis,characterization and thermal behavior on solid tartrates of light trivalent lanthanides

Solid state Ln–L compounds, where Ln stands for light trivalent lanthanides (L–Gd) and L is tartrate, have been synthesized. Thermogravimetry and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration and thermal decomposition of the isolated compounds.     

Cu–Cr–O nanocomposites: Synthesis and characterization as catalysts for solid state propellants

In this article we present the synthesis of Cu–Cr–O nanocomposites via a citric acid (CA) complexing approach and the evaluation of the as-synthesized Cu–Cr–O nanocomposites as additives for the catalytic combustion of AP (ammonium perchlorate)-based solid state propellants. Techniques of thermo-gravimetric/differential thermal analyzer (TG–DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as scanning electron microscopy (SEM) have been employed to characterize the thermal decomposition procedure, crystal phase, micro-structural morphologies and grain size of the as-synthesized materials, respectively. The results show that well-crystallized Cu–Cr–O nanocomposites can be produced by using a temperature as low as 600 °C. Phase structure of the as-obtained Cu–Cr–O nanocomposites depends on the Cu/Cr molar ratio in the starting reactants. Addition of the as-synthesized Cu–Cr–O nanocomposites as catalysts enhances the burning rate as well as lowers the pressure exponent of the AP-based solid state propellants considerably. Noticeably, solid state propellants containing Cu–Cr–O nanocomposites with a Cu/Cr molar ratio of 0.7 exhibits the most stable combustion at all pressures.     

Synthesis,structural characterization,and thermal properties of alkaline (earth) compounds derived from 2,4-dinitroimidazole

Eight alkaline and alkaline-earth compounds derived from 2,4-dinitroimidazole (2,4-HDNI) were synthesized and characterized by elemental analysis, FT-IR, and TG–DSC, of which K(2,4-DNI) (1), Rb(2,4-DNI)(2,4-HDNI)(H₂O)₂ (2), and Ba(2,4-DNI)₂(H₂O)₄ (3) were characterized by single-crystal X-ray diffraction analysis. All the three compounds were crystallized from water, but 1 was an anhydrate. The coordination number in 1 and 3 is 10, but in 2 is 9. The 2,4-DNI adopts either η³, η², or η¹ coordination modes depending on the metal cation. In 3, there is an inversion center located on the metal. Only in 2 does water play an important role for the construction of the structure; in 3 it is a hydrogen bonding participant. TG–DSC analyses of 1 were also performed, and non-isothermal decomposition reaction kinetics were obtained.     

Synthesis of tetrahydroisoquinoline-based pseudopeptides and their characterization as suitable reverse turn mimetics

New peptidomimetics containing the Tic moiety were synthesized in enantiomerically pure form and their conformational features were studied by NMR, IR, and molecular modeling techniques. The presence of a reverse turn conformation was observed in all the structures, suggesting the key role of the scaffold as reverse turn inducer. In particular, all the analyses led to the conclusion that a β-turn conformation is mostly stabilized in tetrapeptide mimetic 4b and in hexapeptide mimetics 5a,b. In the case of 5a,b, the C1 stereochemistry plays a central role in determining stable conformations, supporting the formation of a β-hairpin arrangement with a 14-membered intramolecular hydrogen bond ring only in 5b.     

Synthesis,characterization, and thermal behavior of palladium(II) complexes containing 4-iodopyrazole

The mononuclear pyrazolyl complexes [PdCl₂(HIPz)₂] (1), [PdBr₂(HIPz)₂] (2), [PdI₂(HIPz)₂] (3), [Pd(SCN)₂(HIPz)₂] (4), and [Pd(NHCOIPz)₂] (5) have been prepared. Compound 1 was obtained from the displacement of acetonitrile from [PdCl₂(CH₃CN)₂] precursor by the 4-iodopyrazole (HIPz) ligand, whereas 2–5 were synthesized by substitution of the chlorido in 1 by the respective anionic group. The compounds were characterized by elemental analysis, infrared spectroscopy, and ¹H NMR spectroscopy. The thermal behavior of 1–5 has been studied by TG and DTA. The thermal stability of [PdX₂(HIPz)₂] compounds varies according to the trends X = Cl^? < I^? ? SCN^?< Br^?. No stable intermediates were isolated during the thermal decompositions due to the overlap of the degradation processes. The final products of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction.     

Synthesis of aliphatic amidediol and used as a novel mixed plasticizer for thermoplastic starch

In this paper,aliphatic amidediol was synthesized and mixed with glycerol used as a plasticizer for preparing thermoplastic starch（AGPTPS）.The yield of aliphatic amidediol was 91%.FF-IR expressed that the mixture of aliphatic amidediol and glycerol formed stronger and stable hydrogen bond with starch molecules compared to the native cornstarch.By scanning electron microscope（SEM）native cornstarch granules were proved to transfer to a homogeneous continuous system.After being stored for a period time at room temperature,the mechanical properties of AGPTPS were also studied.As a mixed plasticizer,aliphatic amidediol and glycerol would be practical to extend TPS application scopes.     

Synthesis,characterization, and thermal behavior of palladium(II) coordination compounds containing isonicotinamide

Palladium(II) coordination compounds of general formula trans-[PdX₂(isn)₂], X = Cl⁻ (1), N₃ ⁻ (2), SCN⁻ (3), NCO⁻ (4), isn = isonicotinamide; were synthesized and characterized in solid state by elemental analysis, infrared spectroscopy, and simultaneous TG–DTA. TG experiments reveal that the compounds 1–4 undergo thermal decomposition in three or four stages, yielding Pd⁰ as final residue, according to calculus and identification by X-ray powder diffraction.     

Synthesis,characterization and thermal behaviour of adducts

The photoproduct of octacyanomolybdate(IV) and -tungstate(IV) with ethylenediamine and triethylenetetramine give complexes of the type K₃[Mo(O₂)(O)(OH)(C₉H₇ON)]·3C₉H₇ON I, K₂[W(O₂)(O) (C₉H₇ON)₃] II and K₃[Mo(CN)₃(OH)₄(C₉H₇ON)]·2C₉H₇ON·3H₂O III with 8-quinolinol (oxine). The IR spectra of the complex III shows the presence ofv(CN) peaks in the range 2047–2108 cm^?1 and oxine groupv(C-O) in the complex I, II and III in the range of 1100–1150 cm^?1. The lower region of IR spectra shows the M=O stretching while the higher thev(N-H) andv(OH). Thermal studies show the removal of uncoordinated water at 131?C from complex III. The decomposition of complexes I and II start from 150 and 212?C respectively. Oxine and cyano molecules were removed in stages at higher temperatures. The final product of the thermal decomposition was oxide which was of polymeric nature. The kinetic parameters viz. order of reaction ‘n’ and activation energy ‘E’ were determined by different methods.     

New 12-tungstophosphate-based organic-inorganic hybrid. Synthesis, spectroscopic characterization, X-ray determination and thermal behavior

12-Tungstophosphate-based organic/inorganic hybrid, [HNMPA]₃[O₄₀PW₁₂].0.5NMPA.₂H₂O (NMPA = N-methylpropionamide) was synthesized and characterized by IR, UV-Vis, ¹H, ¹³C and ³¹P NMR spectroscopies, elemental analysis, TGA, DTA and single crystal X-ray determination. Full decomposition of the hybrid leads to WO₃ powder was studied by IR, SEM and XRD.     

Synthesis,characterization, and investigation of the thermal behavior of Cu(II) pyrazolyl complexes

In the present contribution, a procedure to estimate parameters using non-isothermal data was applied. The estimation procedure is based on the use of an energy balance in DSC furnace. The approach found all kinetic parameters of autocatalytic model (E ₁, E ₂, A ₁, A ₂, m, n) besides the ultimate reaction heat and their confidence regions by using deterministic and heuristic algorithms. The application of this approach to isothermal data was done in a previous work and similar results were obtained. The results show that the use of an energy balance is a good methodology to estimate cure kinetic parameters of non-isothermal experiments.     

Synthesis and thermal studies of metal salts of 2,4, N-trinitroanilinoacetic acid

Copper(II), silver(I) and lead(II) salts of N-(2,4-dinitrophenyl)-N-nitroglycine were prepared and characterised. The thermal behaviour of the salts in air and nitrogen atmospheres was studied by means of DTA and TG techniques. The environment appeared to have no effect on the mode of decomposition. While metal oxides are formed as the end-products of decomposition of the copper and lead salts, metallic silver plus carbon was found to be final product from the silver salt. The thermal stabilities of these salts follow the sequence silver salt>lead salt>copper salt.

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Zusammenfassung Kupfer(II)-, Silber(I)- und Blei(II)-Salze von N-(2,4-Dinitrophenyl)-N-nitroglycin wurden hergestellt und charakterisiert. Mittels DTA- und TG-Techniken in Luft- und Stickstoffatmosphäre wurde das thermische Verhalten der Salze untersucht. Die Umgebung scheint auf die Art der Zersetzung keinen Einfluß zu besitzen. Zersetzungsendprodukte der Kupfer ui I Bleisalze sind Metalloxide, Zersetzungsendprodukte des Silbersalzes sind elementares Silber und Kohlenstoff. Die Wärmestabilität dieser Salze sinkt in der Reihenfolge Silbersalt — Bleisalz — Kupfersalz.

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, N-(2,4- )N-. . , . . . > > .

     

Synthesis,characterization, and thermal properties of piezoelectric polyimides

Three amorphous piezoelectric polyimides have been synthesized and characterized to analyze their utility for high‐temperature applications. The studied polyimides have been prepared from 4,4′‐oxydiphthalic anhydride and the diamines 2,4‐di(3‐aminophenoxy)benzonitrile (poly2‐4), 2,6‐bis(3‐aminophenoxy)benzonitrile (poly2‐6), and 1,3‐bis‐2‐cyano‐3‐(3‐aminophenoxy)phenoxybenzene (poly2CN). These polyimides differ in the position of the dipolar groups ? CN in the aromatic ring (poly2‐4 and poly2‐6) and in the number of these groups in the repetitive unit (poly2‐6 and poly2CN). The imidization degree has been studied by Fourier transform infrared (FTIR) and thermogravimetry‐mass spectrometry (TG‐MS) and thermal properties by differential scanning calorimetry (DSC) and thermogravimetry (TG). The piezoelectric behavior has been analyzed from remnant polarization measurements. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 722–730, 2009     

Synthesis,characterization, and thermal properties of ladderlike polyepoxysiloxanes

Starting from trichlorosilanes and using 1,4‐phenylenediamine as a template, we have synthesized some ladderlike poly(glycidyl‐co‐alkyl/aryl)siloxanes (polyepoxysiloxanes or polyepoxies for short). The structures of copolymers were confirmed through IR, ¹H NMR, elemental analyses, and gel permeation chromatography. Curing behaviors of these polyepoxies in the absence and presence of a curing agent have been studied with DSC. It was shown that these epoxies could be cured without any curing agent. Copolymers having aromatic groups showed higher curing reactivity than those having alkyl groups. The experimental results also demonstrate that the curing reaction occurred solely via epoxy functionality, not via the condensation reaction of the hydroxy groups located at the end of polymer main chains. The thermal stability of the cured polymers was examined by thermogravimetric analysis. The results confirm that polyepoxies with aromatic groups had better thermal stability than those with alkyl groups. It was also found that polyepoxies cured with a diamine have a higher thermal stability than those cured in the absence of a curing agent. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2215–2222, 2001     

Synthesis, characterization and thermal properties of metaloquinolate-containing polymers

The monomer, 5-methyl(2-methacryloylethyloxy)-8-quinolinol(HEMA-CH₂-Hq), which possesses both double bond and 8-hydroxyquinoline groups, was synthesized from 2-hydroxyethyl methacrylate (HEMA) and 5-chloromethyl-8-quinolinol hydrochloride. The model polymer with 8-hydroxyquinoline ligands was obtained by free-radical copolymerization with styrene. So metaloquinolate (AlQ₃, ZnQ₂)-containing polymers are prepared by coordinating reaction with di(8-hydroxyquinoline) aluminum(AlQ₂) chelates or mono(8-hydroxyquinoline) zinc(ZnQ) chelates without cross-linking. Both polymer and polymer complexes were analyzed by FT-IR, UV-vis, DSC, TGA and photoluminescence spectroscopies. They are soluble in common solvents and easy to form films. The use of AlQ₂ and ZnQ avoided the cross-linking caused by the AlQ₃, ZnQ₂ formation between different polymer chains. High glass transition temperature, good thermal stability, and strong yellow-green fluorescence were observed for the prepared polymers. These polymers were expected to have the potential application in yellow-green OLEDs.