The High‐Pressure Characterization of Energetic Materials: 2‐Methyl‐5‐Nitramino‐2H‐Tetrazole

The isothermal structural properties, equation of state, and vibrational dynamics of 2MNT were studied under high‐pressure using synchrotron XRD and optical Raman and IR microspectroscopy. Analysis of the XRD patterns revealed no indication of a phase transition to near 15 GPa and the pressure‐volume isotherm remained smooth to 15 GPa. Near 15 GPa, significant sample damage was observed from the X‐ray beam which precluded the acquisition of patterns above this pressure. XRD and Raman spectroscopic measurements showed the monoclinic ambient condition phase of 2MNT remains the dominant phase to near 20 GPa, although a shift of the NO₂ IR active vibrational modes to lower frequencies suggested a subtle geometry modification not reflected in the XRD data.     

Thermodynamic modeling of HNO3‐H2SO4‐H2O ternary system with symmetric electrolyte NRTL model

The nitric acid concentration/sulfuric acid concentration (NAC/SAC) process has been widely used for concentrating dilute aqueous nitric acid and recovering spent sulfuric acid. Dilute nitric acid (65 to 80 wt %) is concentrated using sulfuric acid to bind water and break the nitric acid‐water azeotrope at approximately 68 wt % nitric acid. To support heat and mass balance calculations and process simulation for NAC/SAC processes, we develop a comprehensive thermodynamic model for nitric acid‐sulfuric acid‐water ternary system based on previously published thermodynamic models of nitric acid‐water and sulfuric acid‐water binary systems with eNRTL equation. The ternary system model correlates well the isobaric vapor‐liquid equilibrium data at one atmosphere and the water and nitric acid activities data at 273.15 K for the ternary. Contour plots of boiling points, vapor phase composition, and specific heat capacity of the ternary system, as well as a Merkel enthalpy‐concentration chart are generated for engineering use. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3110–3117, 2017     

Temperature‐induced surfactant‐ mediated pre‐concentration of uranium assisted by complexation

Cloud‐point extraction (CPE) was used with lipophilic chelating agent to extract uranium(VI) from aqueous solutions. The methodology used is based on the formation of metal complexes soluble in a micellar phase of a non‐ionic surfactant, Triton X‐114. The metal ions complexes are then extracted into the surfactant‐rich phase at a temperature above the cloud‐point temperature. The influence of surfactant concentration on extraction efficiency was studied and the advantage of adding 8‐hydroxyquinoline (8HQ) as lipophilic chelating agent was evidenced. High extraction efficiency was observed, indicating the feasibility of extracting U(VI) using CPE. This study describes a four‐step process—(1) extraction, (2) thermo‐induced phase splitting, (3) back‐extraction and (4) second phase splitting—for the recovery of uranium from water. In our conditions, the extraction yield is quantitative and the concentration factor obtained is superior to 100. After stripping with a diluted nitric acid solution (pH < 1), the system can be recycled through a new four‐step cycle. Copyright © 2006 Society of Chemical Industry     

N‐alkylation of chitosan by β‐halopropionic acids in the presence of various acceptors

N‐carboxyethylation of chitosan by β‐halopropionic acids in the presence of various proton and halogen ion acceptors was investigated. It has been observed that carboxyethylation of chitosan in aqueous medium is accompanied by the by‐processes of hydrolysis and dehydrohalogenation of the β‐halopropionic acids yielding β‐hydroxypropionic acid, bis(2‐carboxyethyl) ether, and acrylic acid. Degree of carboxyethyl substitution (DS) of chitosan and the relative rates of the by‐processes varied significantly depending on the conditions used and nature of the proton or halogen ion acceptor. At carboxyethylation of chitosan with the alkaline β‐bromopropionates, the DS increased in the order Cs⁺ < Rb⁺ < K⁺ ～ Na⁺ < Li⁺. For alkaline earth salts BrCH₂CH₂COOM_0.5 (M = Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺), the highest DS was obtained with strontium and barium salts, which could be subsequently removed from the reaction mixture by precipitation as sulfates. Among the organic bases applied (tetrabutylammonium hydroxide, triethylamine, trimethylamine, pyridine, 4‐N,N‐dimethylaminopyridine, 2,6‐lutidine, and 1,5‐diazabicyclo[4.3.0] non‐5‐ene), the highest DS was obtained using a moderately strong base triethylamine. For the halogen acceptors (Pb²⁺, Ag⁺, Tl⁺), the stoichiometrically highest DS was achieved in a system comprising iodopropionic acid plus Tl⁺ and a comparable conversion rate was obtained using also a combination of chloropropionic acid and Ag⁺. A novel alternative preparative approach—gel‐state synthesis—was suggested that provides for the highest DS at the optimum reaction conditions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of soluble poly(amide‐imide)s bearing triethylamine sulfonate groups as gas dehumidification membrane material

A series of soluble poly(amide‐imide)s (PAIs) bearing triethylammonium sulfonate groups were synthesized directly using trimellitic anhydride chloride (TMAC) polycondensation with sulfonated diamine such as 2,2′‐benzidinedisulfonic acid (BDSA), 4,4′‐diaminodiphenyl ether‐2,2′‐disulfonic acid (ODADS), and nonsulfonated diamine 4,4‐diaminodiphenyl methane in the presence of triethylamine. The resulting copolymers exhibited high molecular weights (high inherent viscosity), and a combination of desirable properties such as good solubility in dipolar aprotic solvents, film‐forming capability, and good mechanical properties. Wide‐angle X‐ray diffraction revealed that the polymers were amorphous. These copolymers showed high permeability coefficients of water vapor because of the presence of the hydrophilic triethylammonium sulfonate groups. The water vapor permeability coefficients (P_w) and permselectivity coefficients of water vapor to nitrogen and methane [α(H₂O/N₂) and α(H₂O/CH₄)] of the films increased with increasing the amount of the triethylammonium sulfonated groups. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Dual electroluminescence from a single‐component light‐emitting electrochemical cell,based on water‐soluble conjugated polymer

Poly [[2‐methoxy‐5‐(3‐sulfonatopropoxy)‐1, 4‐phenylene]‐1, 2‐ethenediyl] (MPS‐PPV) was an anionic water‐soluble conjugated polymer. A novel single‐component light‐emitting electrochemical cell (LEC) with an indium tin oxide/MPS‐PPV/aluminum sandwich structure has been successfully fabricated. MPS‐PPV serves as both luminescent material and ionic conductor in the active layer. Electroluminescence can be observed under both forward and reverse bias with emission maxima at about 520 nm (green light). In particular, the device has a low turn‐on voltage of about +3V and ?4V, and can sustain long‐term operations without much loss of efficiency at ambient conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2930–2936, 2006     

Stimuli‐sensitive behaviour of novel betaine‐type polyampholytes

Novel linear and crosslinked polyampholytes of betaine structure based on acrylic acid and ethyl 3‐aminocrotonate (ethyl ester of 3‐amino‐2‐butenoic acid) have been synthesized by Michael addition reaction followed by radical copolymerization. The mechanism of formation of monomer and polymer betaines is discussed. The linear polyampholyte has been characterized by potentiometric titration, IR, NMR and GPC. Crosslinked polymeric betaines were synthesized in the presence of N,N′‐methylenebisacrylamide. The stimuli‐sensitive properties of amphoteric gels have been studied as a function of pH, ionic strength, water–organic mixture composition, electric, and combined electric and magnetic fields. The isoelectric points of linear and crosslinked polymeric betaines correspond to pH 2.0–2.1. The effect of ionic strength on the solution and gel properties of polybetaine has been interpreted on the basis of destruction of inter‐chain, intra‐chain and intra‐group salt bonds. Water–acetone, water–ethanol or water–DMF mixtures cause the shrinking of amphoteric gel due to change of the dielectric constant of the medium and decrease of the osmotic pressure. Electrocollapse is observed under the action of DC electric field. Simultaneously cross action of electric and magnetic fields enhances the collapsing rate. Appearance of pH gradient within the volume of polyampholyte gel under the externally imposed DC electric field has been observed. Copyright © 2003 Society of Chemical Industry     

Effect of temperature,solvent, Lewis acid and additives on the polymerization of tert‐butyl vinyl ether using Lewis acid‐induced N‐methyleneamines as cationic initiators

N‐Methyleneamines, formed by treating 1,3,5‐trimethylhexahydro‐1,3,5‐triazines with Lewis acids, have been shown to be capable initiators in the cationic polymerization of tert‐butyl vinyl ether, yielding polymers with amine functionality at the chain ends. Previous work was limited to titanium(IV) chloride (TiCl₄) as the Lewis acid in dichloromethane solvent at 0 °C (with resulting polymers possessing relatively broad polydispersity index (PDI) values near 2), while this contribution details the effect of reaction parameters on the polymeric products; specifically, the role of temperature, solvent, Lewis acid and additives. Ultimately, performing the polymerization at ?78 °C in dichloromethane with TiCl₄ as the Lewis acid and tetra‐n‐butylammonium chloride (nBu₄NCl) as the additive afforded the best control over the system, with polymers formed possessing low PDI values (<1.2). Dramatic changes in number‐average molecular weight and PDI were observed in polymers formed by initiating systems of Lewis acid‐induced N‐methyleneamines, with temperature, solvent, Lewis acid and additives all playing a role. By varying single parameters, optimization of the system was achieved. Copyright © 2009 Society of Chemical Industry     

The High‐Pressure Characterization of Energetic Materials: Diaminotetrazolium Nitrate (HDAT‐NO3)

In‐situ high‐pressure room temperature synchrotron X‐ray diffraction and optical Raman and infrared spectroscopy were used to examine the structural properties, equation of state, and vibrational dynamics of diaminotetrazolium nitrate (HDAT‐NO₃). The X‐ray measurements show that the pressure–volume relations remain smooth to 12 GPa. X‐ray diffraction measurements at pressures above 12 GPa were not possible in this study because of sample decomposition resulting from several factors. X‐ray diffraction reveals no indication of a phase transition to at least 12 GPa, but slight variations in the c/b unit cell ratio suggests modifications within the hydrogen bonding sub‐lattice. Vibrational measurements show the ambient phase of HDAT‐NO₃ to remain the dominant phase to 33 GPa.     

Development of ZrO2‐MgO nanocomposite powders by the modified sol‐gel method

The ZrO₂‐MgO nanocomposites were synthesized using a new sol‐gel method with sucrose and tartaric acid as a gel agent. The samples were characterized by thermal analysis (TG/DTA), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray mapping (EDX mapping), and Ultraviolet‐visible spectroscopy (UV‐vis). The results showed that the cubic phase of ZrO₂‐MgO was formed in the presence of both gel agents. The average particle size of the samples synthesized with sucrose was lower (30 nm) than that of tartaric acid (50 nm). Finally, the formation mechanism and the optical properties of zirconia‐magnesia have been discussed.     

Conducting composites of poly(N‐vinylcarbazole), polypyrrole,and polyaniline with 13X‐zeolite

N‐vinylcarbazole (NVC) was polymerized by 13X zeolite alone in melt (65°C) or in toluene (110°C) and a poly(N‐vinylcarbazole) (PNVC)‐13X composite was isolated. Composites of polypyrrole (PPY) and polyaniline(PANI) with 13X zeolite were prepared via polymerization of the respective monomers in the presence of dispersion of 13X zeolite in water (CuCl₂ oxidant) and in CHCl₃ (FeCl₃ oxidant) at an ambient temperature. The composites were characterized by Fourier transform infrared analyses. Scanning electron microscopic analyses of various composites indicated the formation of lumpy aggregates of irregular sizes distinct from the morphology of unmodified 13X zeolite. X‐ray diffraction analysis revealed some typical differences between the various composites, depending upon the nature of the polymer incorporated. Thermogravimetric analyses revealed the stability order as: 13X‐zeolite > polymer‐13X‐zeolite > polymer. PNVC‐13X composite was essentially a nonconductor, while PPY‐13X and PANI‐13X composites showed direct current conductivity in the order of 10^?4 S/cm in either system. However, the conductivity of PNVC‐ 13X composite could be improved to 10^?5 and 10^?6 S/cm by loading PPY and PANI, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 913–921, 2006     

A water‐soluble supramolecular‐structured photoinitiator between methylated β‐cyclodextrin and 2,2‐dimethoxy‐2‐phenylacetophenone

A water‐soluble supramolecular‐structured photoinitiator (SSPI) was synthesized by supramolecular self‐assembling between methylated β‐cyclodextrin (MβCD) and hydrophobic 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA). The structure of SSPI was characterized by X‐ray diffraction, FTIR, ¹H NMR, UV–vis, and fluorescence spectra. The results indicated that MβCD and DMPA had formed 1 : 1 inclusion complex in methanol solution. The binding constant (K) for the complex was 7.51 × 10²M^?1. SSPI could be dissolved in water easily and its water‐solubility was 15.3 g/100 mL. SSPI was the more efficient photoinitiator than DMPA for the photopolymerization of acrylamide (AM) in homogeneous aqueous system. The conversion for photopolymerization of trimethylolpropane triacrylate system initiated by SSPI was similar to that initiated by DMPA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A new tri‐functional azetidine compound for self‐curing aqueous‐based PU system

A mono‐azetidine compound had been demonstrating a ring opening reaction with carboxylic acid (e.g., trimethylacetic acid, TMAA) and that resulted in an amino ester bond formation at ambient temperature. A triazetidine compound (trimethylolpropane tris(1‐azetidinyl)propionate, TMPTA‐AZT) was obtained via Michael addition of azetidine (AZT) to trimethylolpropane triacrylate (TMPTA). The carboxylic groups of anionic aqueous‐based polyurethanes (PU) served as internal emulsifier, which stabilized PU dispersion and also served as PU curing sites. The triazetidine compound (TMPTA‐AZT) was introduced into anionic aqueous‐based PU dispersion as a new latent curing agent and that mixture became a single‐component self‐curable aqueous PU system. A crosslinked PU film was obtained from this PU system on drying at ambient temperature. The final polymer performance properties demonstrated the crosslinking behaviors of this new curing agent, TMPTA‐AZT, with carboxylic ion‐containing aqueous‐based PU resins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Study on liquid‐phase hydrogenation of paranitrotoluene over Ru‐based catalysts

This paper presented a study on the role of yttrium addition to Ru‐based catalysts for liquid phase paranitrotoluene hydrogenation reaction. An impregnation‐precipitation method was used for preparation of a series of yttrium doped Ru/NaY catalysts with yttrium content in the range of 0.0026–0.0052 g/g. Properties of the obtained samples were characterized and analyzed by X‐ray diffraction (XRD), H₂‐TPR, Transmission electron microscopy (TEM), ICP atomic emission spectroscopy, and Nitrogen adsorption‐desorption. The results revealed that catalytic activity of NaY supported Ru catalysts increased with the yttrium content at first, then decreased with the further increase of yttrium content. When yttrium content was 0.0033 g/g, a Ru‐Y/NaY² catalyst showed the most excellent performance of paranitrotoluene hydrogenation reaction (paranitrotoluene conversion and the selectivity toward P‐methyl‐cyclohexylamine reached 99.9 % and 82.5 %, respectively). In addition, to compare with the performance of Ru‐Y/NaY catalysts, the active carbon supported Ru catalysts were prepared using the same method in view of its higher surface area and adsorption capacity. Finally, the effect of solvent on the reaction over Ru‐Y/NaY² catalyst has been investigated, it was found that the best performance of paranitrotoluene hydrogenation reaction took place in protic solvents (isopropanol and ethanol). This was mainly ascribed to their polarity and hydrogen‐bond accepting capability.

     

The High‐Pressure Characterization of Energetic Materials: 1‐Methyl‐5‐Nitramino‐1H‐Tetrazole

Pressure–volume relations and optical Raman and Infrared spectra of polycrystalline 1MNT have been obtained under quasi‐hydrostatic conditions up to 16 and 40 GPa, respectively, by using diamond anvil cell, synchrotron‐based angle‐resolved X‐ray diffraction, and microspectroscopy. The X‐ray measurements show that the pressure–volume relations remain smooth up to 16 GPa at room temperature, while vibrational measurements show no evidence of a phase transition to near 40 GPa. Anomalous increases of several vibrational intensities and bandwidths suggest that subtle molecular distortions and structural modifications occur in the crystal as pressure increases. Decompression experiments indicate the structural modifications are reversible.     

Microwave‐Promoted Copper‐Free Sonogashira–Hagihara Couplings of Aryl Imidazolylsulfonates in Water

Aryl imidazol‐1‐ylsulfonates have been efficiently cross‐coupled with aryl‐, alkyl‐, and silylacetylenes in neat water under copper‐free conditions at 110 °C assisted by microwave irradiation. Using 0.5 mol% of an oxime palladacycle as precatalyst, 2‐dicyclohexylphosphino‐2′,6′‐dimethoxybiphenyl (SPhos, 2 mol%) as ligand, hexadecyltrimethylammonium bromide (CTAB) as additive, and triethylamine (TEA) as base, a wide array of disubstituted alkynes has been prepared in good to high yields in only 30 min.     

Dead Zones in LX‐17 and PBX 9502

Pin and X‐ray corner turning data have been taken on ambient LX‐17 and PBX 9052, and the results are listed in tables as an aid to future modeling. The results have been modeled at 4 zones/mm with a reactive flow approach that varies the burn rate as a function of pressure. A single rate format is used to simulate failure and detonation in different pressure regimes. A pressure cut‐off must also be reached to initiate the burn. Corner turning and failure are modeled using an intermediate pressure rate region, and detonation occurs at high pressure. The TATB booster is also modeled using reactive flow, and X‐ray tomography is used to partition the ram‐pressed hemisphere into five different density regions. The model reasonably fits the bare corner turning experiment but predicts a smaller dead zone with steel confinement, in contradiction with experiment. The same model also calculates the confined and unconfined cylinder detonation velocities and predicts the failure of the unconfined cylinder at 3.75 mm radius. The PBX 9502 shows a smaller dead zone than LX‐17. An old experiment that showed a large apparent dead zone in Composition B was repeated with X‐ray transmission and no dead zone was seen. This confirms the idea that a variable burn rate is the key to modeling. The model also produces initiation delays, which are shorter than those found in time‐to‐detonation.     

Promoted Fe2O3‐Al2O3‐CuO Chromium‐Free Catalysts for High‐Temperature Water‐Gas Shift Reaction

Promoted Fe₂O₃‐Al₂O₃‐CuO (FAC) chromium‐free catalysts were prepared for high‐temperature water‐gas shift reactions and characterized by X‐ray diffraction (XRD), Brunauer‐Emmett‐Teller method (BET), temperature‐programmed reduction (TPR), and transmission electron microscopy (TEM) techniques. The catalytic results revealed that among the investigated promoted catalysts with Ce, La, Zn, Y, and Mn as promoters, the Mn‐promoted sample showed higher activity compared to the other promoted catalysts. Increasing the Mn content improved the surface area and catalytic activity. The FAC catalyst promoted with a high Mn content exhibited maximum activity and relatively high stability in high‐temperature water‐gas shift reaction.     

Synthesis,characterization of the luminescent lanthanide complexes with copolymer of (Z)‐4‐oxo‐4‐phenyloxyl‐2‐butenoic acid and styrene

The copolymers of (Z)‐4‐oxo‐4‐phenoxyl‐2‐butenoic acid with styrene (PSt/OPBA) and their macromolecular luminous lanthanide complexes (Ln‐PSt/OPBA) have been synthesized and characterized by means of GPC, elemental analysis, FTIR, X‐ray powder diffraction, spectral analysis, and thermal analysis. The IR studies showed that the carboxylic groups on the side chain of the polymer were coordinated to lanthanide ions by bidentate manner. However, the ethereal oxygen, instead of carbonyl, also bonded to the central lanthanide ions, which was an intriguing phenomenon for ester‐coordinated complexes. X‐ray diffraction experiments revealed that these PSt/OPBA copolymers were amorphous, but Ln‐PSt/OPBA were crystalline, in which the complex Eu‐L^c belonged to a high symmetric structure of orthorhombic quadratic system, with a = 10.59 ± 0.02 Å, c = 8.02 ± 0.01 Å; c/a = 0.763. In addition, the value δ (the number of free carboxylic groups) in Ln‐PSt/OPBA complexes increased with the decreasing mole ratio of styrene in the copolymers, while it decreased with increasing pH values of the solution. Eu³⁺ and Tb³⁺ complexes exhibited characteristic fluorescence with comparatively high brightness and good monochromaticity, and the fluorescence intensity was enhanced with increasing the content of lanthanide up to around 18 wt % without typical fluorescence concentration quenching behavior in the solid state. So using polymers as a matrix, Ln‐PSt/OPBA are likely to provide new materials that possess specific properties and desired features. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of isooctanol on the interfacial activity and mass transfer of ytterbium(III) using 2‐ethylhexylphosphonic acid mono‐2‐ethylhexyl ester as an acidic extractant

BACKGROUND: Introducing an adduct into an extractant system is an effective method of improving extraction performance. The effect of additives upon extraction is very important, especially in the case of interfacial behaviour. In most work published in the literature, there is little data on the interfacial behaviour of extractants and modifiers. As the mass transfer must pass through an interface, the influence of isooctanol on the interfacial activity and mass transfer of ytterbium(III) using 2‐ethylhexylphosphonic acid mono‐2‐ethlhexyl ester has been investigated. RESULTS: With increasing amounts of isooctanol, the interfacial tension and surface excess (Γ_max) of the 2‐ethylhexylphosphonic acid mono‐2‐ethylhexyl ester(HEHEHP)–isooctanol system decreased, and the area of the absorbed HEHEHP molecule (A_min) increased. The interfacial activity of the HEHEHP–isooctanol system varied significantly depending on ionic strength and temperature and the mass transfer flux decreased with increasing isooctanol content. CONCLUSION: Isooctanol has a strong influence on the interfacial activity of the HEHEHP system. The influence of isooctanol on the mass transfer rate of ytterbium extraction has been discussed qualitatively. Copyright © 2008 Society of Chemical Industry