Iodine Pentoxide Nano‐rods for High Density Energetic Materials

The iodine pentoxide is one of the most advanced oxidizers for nanostructured energetic formulations among the thermites due to the highest energy release per volume 25.7 kJ cm⁻³. The size and shape of iodine pentoxide particles have a strong impact on the pressurization rates during the reaction. Although micro‐sized iodine pentoxide particles are commercially available, nano‐sized particles, which are desired for various nano‐energetic applications, are not available on the market. Conventional wet chemical methods are unable to produce iodine pentoxide nanoparticles due to high solubility in water. In this study, we demonstrate fabrication of iodine pentoxide nano‐rods by high energy mechanical treatment of micro‐sized I₂O₅ particles. Tuning the energy dose in high‐energy ball milling is allowing to produce I₂O₅ nano‐rods with diameter of 50–100 nm and length of 300–600 nm. The produced nano‐rods exhibited 10 % smaller decomposition energy compared to the precursor of micro particles. The experiments showed that the nano‐energetic materials prepared with nano‐sized I₂O₅ rods have pressure discharge value of 43.4 MPa g⁻¹ which is two times higher than using commercial iodine pentoxide particles.     

Graphite intercalation compound with iodine as the major intercalate

Halogenated graphite CBr_xI_y (1 < y/x < 10) was made by exposing graphite materials to either pure Br₂ or an I₂/Br₂/HBr mixture to initiate the reaction, and then to iodine vapor containing a small amount of Br₂/HBr/IBr to complete the intercalation reaction. Wetting of the graphite materials by the I₂/Br₂/HBr mixture is needed to start the reaction, and a small amount of Br₂/HBr/IBr is needed to complete the charge transfer between iodine and carbon. The interplanar spacings for the graphite materials need to be in the 3.35 to 3.41 Å range. The X-ray diffraction data obtained from the halogenated HOPG indicate that the distance between the two carbon layers containing intercalate is 7.25 Å. Electrical resistivity of the fiber product is from 3 to 6.5 times the pristine value. The presence of a small amount of isoprene rubber in the reaction significantly increased the iodine-to-bromine ratio in the product. In this reaction, rubber is known to generate HBr and to slowly remove bromine from the vapor. The halogenation generally caused a 22% to 25% weight increase. The halogens were found uniformly distributed in the product interior. However, although the surface contains very little iodine, it has high concentrations of bromine and oxygen. It is believed that the high concentrations of bromine and oxygen in this surface cause the halogenated fiber to be more resistant to structural damage during subsequent fluorination to fabricate graphite fluoride fibers.     

Burning Characteristics and Sensitivity Characteristics of Some Guanidinium 1,5′‐bis‐1H‐Tetrazolate/Metal Oxide Mixtures as Candidate Gas Generating Agent

Burning characteristics and sensitivity characteristics of some stoichiometric ratio guanidinium 1,5′‐bis‐1H‐tetrazolate (G15B)/metal oxide mixtures were examined. The linear burning rates of the G15B/CuO mixture were higher compared to other G15B/metal oxide mixtures and 5‐amino‐1H‐tetrazole(5‐ATZ)/Sr(NO₃)₂ mixture, although the average rate of pressure rise during the closed vessel test was lower compared to 5‐ATZ/Sr(NO₃)₂ mixture. The temperature rise for both G15B/CuO and G15B/MnO₂ mixtures was considerably lower than that of 5‐ATZ/Sr(NO₃)₂ mixture. G15B/Fe₂O₃ mixture was the most insensitive among G15B/metal oxide mixtures during the drop hammer test, while G15B/CuO mixture was the second most insensitive. All G15B/metal oxide mixtures were insensitive against friction and electric spark discharge (ESD). Four seconds ignition temperature for G15B/CuO mixture was over 100 K lower than that of 5‐ATZ/Sr(NO₃)₂ mixture, but the apparent activation energy for ignition was higher. Among the G15B/metal oxide mixtures studied, G15B/CuO mixture showed the fastest burning rate, while it showed a relatively low temperature rise and low sensitivity. G15B/ZnO did not burn at all.     

Research on the preparation and characterization of chitosan grafted polyvinylpyrrolidone gel membrane with iodine

The chitosan grafted polyvinylpyrrolidone gel membrane with iodine (CS‐PVP‐I₂‐G‐M) was prepared by chitosan–polyvinylpyrrolidone–iodine complex liquid (CS‐PVP‐I₂‐L) mixed with gelatin. The intermediate product CS‐PVP‐I₂‐L was prepared by CS grafted PVP in the protection of N₂ with dimethyl 2,2′‐azobis (2‐methylpropionate) (AIBME) as initiator, then a certain amounts of iodine in ethanol solution was added. The properties of CS‐PVP‐I₂‐G‐M were characterized by IR, UV–Vis, SEM, XRD, DSC, and so forth. The iodine release results coherent with the release kinetic model—Fick diffusion laws, has a burst effect first, and then spread, and the emission of iodine was maintained within a certain range and kept at a stable level permanently, showed a sustained‐release effect of iodine. The inhibition zone diameters of CS‐PVP‐I₂‐G‐M against Staphylococcus aureus and Escherichia coli were both greater than 16 mm, it demonstrated significant antibacterial activity. Double effects sustained‐release effect of iodine and the significant antibacterial activity made CS‐PVP‐I₂‐G‐M highly potential for applications as a novel natural biomedical sterilization materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41797.     

Effect of boric acid and heat treatment for the formation of poly(vinyl alcohol)/iodine complex films iodinated at solution before casting

This study examined the role of boric acid and the effect of heat treatment on PVA‐iodine polarizing films prepared in the solution state before casting (IBC) of PVA/iodine/boric acid films. The films were prepared by casting aqueous solutions of 10 wt % poly(vinyl alcohol) (PVA) containing boric acid with 0, 0.1, 0.3, and 0.5 mol/l of I₂/KI aqueous solution, and I₂/KI(1 : 2) with 5 wt % of PVA. The effect of boric acid and heat treatment on the durability of the IBC PVA polarizing sheet films was investigated by UV–vis absorption spectroscopy. Boric acid was found to be essential for the complex formation in PVA/iodine solutions at relatively low I₂/KI concentrations and high temperatures. The strength of the complex peak at ∼ 600 nm in UV–vis absorption spectra increased with increasing boric acid concentration. With increasing heating temperature over 90°C the intensity of the peak at 600 nm corresponding to the complex decreased due to the evaporation of I₂ decomposed from I₅⁻, but the peak at 355 nm corresponding to free I₂·I₃⁻ was remained unchanged. From heat treatment at 150°C, the intensity of the peak at 600 nm decreased but the intensity of the complex peak (600 nm) of the sample with 0.5 mol/l boric acid was unaffected. The transmittance and degree of polarization for the films increased and decreased with increasing heat treatment time under heat and a humid atmosphere, respectively. However, this tendency decreased with increasing boric acid concentration and heat treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Low‐temperature conversion of spent adsorbent to iodine sodalite by a mechanochemical route

The focus on a ball milling induced conversion as a possible synthesis route of iodine sodalite (Na₈Al₆Si₆O₂₄I₂) from zeolite‐based iodine adsorbents in order to treat a radioactive iodine filter for the off‐gas cleaning during nuclear facilities is presented. A mixture of silver iodide and zeolite 13X as a simulated adsorbent was mechanochemically milled using a laboratory‐scale planetary ball mill. The obtained powders were characterized by X‐ray diffraction to determine the effect of milling time on the conversion of the iodine sodalite. The crystal grain size and the lattice strain of the grounded phases were evaluated. After the ball milling, the milled samples were hydrothermally crystallized to form a sodalite phase with a sodium hydroxide solution for 48 h in an autoclave maintained at 150^°C. The iodine sodalite was successfully obtained after hydrothermal crystallization. A leaching test was carried out for the assessment of the order of iodine leachability and chemical durability under reducing conditions. The leaching amount was found to be low on the orders of 10^?4 ～10^?5 mol dm^?3 in sodium thiosulfate solution. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2441–2447, 2012     

The reaction of polyaniline with iodine

Polyaniline (PANI) (emeraldine) base has been exposed to iodine in an ethanol-water suspension. The conductivity of PANI increased from 10⁻⁹ S cm⁻¹ to 10⁻⁴ S cm⁻¹ already at the molar ratio [I₂]/[PANI] = 1, and a higher content of iodine had only a marginal effect. This is the result of the protonation of PANI base with hydriodic acid, which is a by-product of the oxidation of the emeraldine form of PANI to pernigraniline constitutional units. The reaction is discussed on the basis of FTIR spectra. An alternative reaction, a ring-iodination of PANI, is marginal. Only one iodine atom substitutes a hydrogen atom in about 12 aniline units, even at high iodine concentration, [I₂]/[PANI] = 8. The film of polyaniline base can be used in sensing iodine; after exposure to the iodine vapor, the conductivity of the polyaniline film increased.     

Research on the preparation and antibacterial properties of 2‐N‐thiosemicarbazide‐6‐O‐hydroxypropyl chitosan membranes with iodine

The 2‐N‐thiosemicarbazide‐6‐O‐hydroxypropyl chitosan (ATU‐HPCS) was prepared by chitosan grafted hydroxypropyl and thiosemicarbazide through the method of “amino protection‐graft‐deprotection,” while the ATU‐HPCS gel membranes were obtained from gelatin and polyvinyl pyrrolidone as additives, and the ATU‐HPCS membranes with iodine (ATU‐HPCS‐I₂‐M) were prepared by adding the ethanol solution of iodine in the ATU‐HPCS gel membranes. The ATU‐HPCS‐I₂‐M were characterized to evaluate their potential applications as antibacterial materials. The iodine releasing rule of ATU‐HPCS‐I₂‐M showed a sustained‐release effect of iodine, the maximum emission was approximately 0.80%. The inhibition zone diameters of ATU‐HPCS‐I₂‐M against Staphylococcus aureus (as Gram‐positive bacteria) and Escherichia coli (as Gram‐negative bacteria) were both greater than 15 mm, it demonstrated significant antibacterial activity compared with the ATU‐HPCS gel membranes. The double effects of the biocompatibility of chitosan and the sustained‐release of iodine provided an ideal healing environment for wound surface. These properties have made ATU‐HPCS‐I₂‐M highly potential as a novel natural macromolecule antimicrobial material preventing the bacteria from burns, surgery wounds, etc. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40535.     

Physiochemical Characterization of Iodine(V) Oxide,Part 1: Hydration Rates

In the first of a series of papers on the iodine(V) oxide system, the chemical and physical properties associated with iodine(V) oxide in its anhydride (I₂O₅) and hydrated states (HI₃O₈ and HIO₃) are examined. The three forms of the oxide have been investigated utilizing differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and powder X‐ray diffraction (PXRD). Furthermore, the hydration rates governing the conversion of the anhydride (I₂O₅) to the initial hydrate (HI₃O₈) and later to the final hydrated state (HIO₃) are reported and discussed. Results from this study suggest that the hydration mechanism for I₂O₅→HI₃O₈ begins with an accelerating period described as a nucleation and growth phase followed by a decelerating period that is diffusion limited. The initial rate of hydration was observed to be governed by a nucleation and growth mechanism, which was inhibited by covering the surface of the particle with an inert metal. Based on this investigation the initial rate of hydration appears to be strongly dependent on the anhydride’s available surface area which facilitates nucleation and growth of HI₃O₈. The final step, HI₃O₈→HIO₃, proceeds through an initial induction period followed by a continuous acceleratory period unlike the first hydration step.     

Laser Ignition of Nano‐Composite Energetic Loose Powders

Laser ignition experiments were conducted to better understand parameters that influence ignition of energetic materials. A Nd:YAG laser (10 ms, 1.5 J, 3 mm spot diameter) was used to heat the top surface of an energetic powder composed of nanometric aluminum (Al) combined stoichiometrically with an oxidizer (copper oxide (CuO), iodine pentoxide (I₂O₅), polytetrafluoroethylene (C₂F₄), molybdenum trioxide (MoO₃) or iron oxide (Fe₂O₃)). Ignition delay time was calculated as the difference between first light of the laser’s flash lamp and the energetic material. Results show that laser energy required for ignition is dependent on pre‐ignition reactions, phase change/decomposition temperatures, confinement, and laser absorbance.     

Removing H2S from Biogas Using Sorbents for Solid Oxide Fuel Cell Applications

Desulfurization of biogas is essential for its application in solid oxide fuel cells. The influence of CH₄, CO₂, H₂, and O₂ as well as the effect of moisture onto desulfurization performance of an activated carbon, an adsorbent based on a CuO‐MnO mixture, and a zeolite adsorbent were analyzed. The use of moisturized gas had no negative influence on the H₂S adsorption performance of activated carbon. The CuO‐MnO sorbent showed the best performance, but the presence of moisture had a negative influence. The performance of zeolite dropped for three gas mixtures, while for two other mixtures moisture had little to no influence on H₂S adsorption performance.     

Cationic starch iodophores

Cross‐linked cationic starches N‐(2‐hydroxyl)propyl‐3‐trimethyl ammonium starch chloride (CQS chloride), N‐(2‐hydroxyl)propyl‐3‐trimethyl ammonium starch iodide (CQS iodide), and N‐(2‐hydroxyl)propyl‐3‐trimethyl ammonium starch iodide–iodine (CQS triiodide) with the degree of substitution (DS) according to cationic groups from 0.04 to 0.62, as well as cross‐linked starch–iodine complexes were synthesized and tested as potential antibacterial agents. Cationic starch iodine derivatives were obtained during ion exchange reaction between CQS chloride and iodide or iodide–iodine anions in aqueous solutions. CQS_DS≤0.3 chloride can form several types of iodine complexes, such as the blue amylose–iodine inclusion complex and ionic CQS⁺I^?·(I₂)_m complex (m ≥ 1). The antibacterial activity of modified starches–iodine samples against different pathogenic bacterial cultures and contaminated water microorganisms was evaluated. CQS chloride and CQS iodide were found to be bacteriostatic. A strong antibacterial activity was characteristic of CQS triiodides in which molecular iodine is present in both ionic and inclusion complexes. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Radial Combustion Propagation in Iron(III) Oxide/Aluminum Thermite Mixtures

The self‐sustained thermite reaction between iron oxide (Fe₂O₃) and aluminum is a classical source of energy. In this work the radial combustion propagation on thin circular samples of stoichiometric and over aluminized Fe₂O₃/Al thermite mixtures is studied. The radial geometry allows an easy detection of sample heterogeneities and the observation of the combustion behavior in their vicinity. The influence of factors like reactant mixtures stoichiometry, samples green density and system geometry on the rate of propagation of the combustion front is analyzed. The radial combustion front profiles are registered by digital video‐crono‐photography. Combustion thermograms are obtained for two sample radii. Theoretical calculations, based on the impurity levels reported by the reactants manufacturers and on the thermite reaction stoichiometry, were used to define the stoichiometric mixture with unitary equivalence ratio (E. R.). However, it was found from the experimental results that the excess of aluminum only starts for E. R. values between 1.12 and 1.27. This was explained by the further oxidation of aluminum during storage and/or by the reaction incompleteness. In the range studied, the combustion rates of the thermite mixtures did not show any significant dependence on the green density. Combustion rates obtained in this work were slightly higher than those obtained in an earlier work for long square channel geometry. A considerable dispersion of temperature values was observed and attributed to thermocouples sensitivity to micro‐scale variations.     

The Effect of Interfacial Tension on the Adhesion of Cathodic E-coat to Aluminum Alloys

Adhesion of a cathodically electrodeposited paint (E-coat) to aluminum alloys, Alclad 2024-T3, AA 2024-T3 and AA 7075-T6, was investigated to examine the influence of interfacial tension at the paint/metal interface. The surface energy of an aluminum plate was modified by depositing a plasma polymer of a mixture of trimethyl silane (TMS) and one of three diatomic gases (O₂, N₂, and H₂) by cathodic plasma polymerization. The contact angle (Φ) of water on a modified surface changes as a function of the mole fraction of the diatomic gas. The plot of cos Φ_PP of a plasma polymer as a function of the mole fraction of the gas crosses the plot of cosΦ_EC of the E-coat. The difference, ΔCosΦ = cos Φ_PP - cosΦ_EC, is a parameter which indicates the level of interfacial tension at the paint/metal interface. ΔCosΦ = 0 represents the minimum interfacial tension. The adhesion of a cured E-coat on a panel was evaluated by the N-methyl pyrrolidinone (NMP) paint delamination time test. The maximum peak of adhesion test values plotted as a function of ΔCosΦ occurred around the zero point. ΔCos Φ = 0, indicating that maximum adhesion is obtained with minimum interfacial tension. Mixtures of TMS and N₂ on all three aluminum alloys studied consistently displayed longer delamination times in the NMP test than mixtures of TMS and O₂ or H₂.     

非平衡碘负离子转化二氧化碳

以直流脉冲负高压电晕放电形式,通过加入电子亲和能较高的碘气,在完全电负性离子体条件下资源化处理CO₂。考察了进气流量、高压放电频率和原料摩尔比对CO₂转化率的影响。结果表明:70℃时,利用碘负离子成功将CO₂还原生成了CI₄,其产率随着CO₂流量的增加而减少。当进气流量0.06 L·min^-1、放电频率9.608 kHz,n(I₂)/n(CO₂)为2.5时,CO₂转化率在碘负离子作用下达到88.71%。另外,对碘负离子和CO₂还原反应机理进行了初步探讨。     

Phase Constitution and Dynamic Properties of Spark Plasma‐Sintered Alumina–Titanium Composites

Al₂O₃/Ti composites of various metal to ceramic ratios were fabricated by the spark plasma sintering (SPS) technique. The effects of titanium concentration in the initial mixture on phase composition, and on the static and dynamic (planar impact testing) mechanical properties of the SPS‐processed composites were investigated. It was observed that the significant alumina dissolution in titanium takes place during SPS treatment. The composites fabricated from starting alumina/titanium powder mixtures with a mass fraction of titanium less than 0.8 consisted of two phases, alumina and a solid solution of oxygen and aluminum in titanium. For starting mixtures with higher titanium content, the presence of a Ti₃Al intermetallic phase with a relatively low fraction of dissolved oxygen was detected. Changes in phase composition could explain the effect of titanium content in the starting mixture on physical and mechanical properties of the composites. Mechanisms governing the dynamic response of the composites under loading of different intensities are discussed.     

Study of Some Low Temperature Gas‐Generating Compositions

Some low temperature gas‐generating compositions, comprised of guanidine nitrate (GN), basic cupric nitrate (BCN), and ferric oxide (Fe₂O₃), were studied herein. The thermal decomposition properties and burning characteristics of GN/BCN/Fe₂O₃ mixtures were investigated by thermogravimetry/differential scanning calorimetry (TG/DSC), burning temperature measurements, automatic calorimetry, and X‐ray diffraction (XRD). This study showed that the maximum burning temperature of GN/BCN/Fe₂O₃ mixture (613 °C) was 31 % lower than that of GN/BCN mixture and the corresponding heat of combustion (2647 J g⁻¹) decreased by 15 %. When the GN/BCN/Fe₂O₃ mixtures were burning, Fe₂O₃ did not directly react with GN but with Cu (or CuO), which was produced by reaction between GN and BCN. The combustion process of GN/BCN/Fe₂O₃ grains could be divided into four stages: pre‐heated, condensed, combustion, and cooling.     

Electrochemical features of Al/I2 batteries in water and non-aqueous solution

An attempt was made to clarify the transport mechanism of a promising energy storage system of Al-I₂ batteries in both aqueous and non-aqueous solution for the first time. The different discharge features of the Al-I₂ cells in the water and the acetonitrile solution were revealed. Ac impedance spectra indicated that the resistance of the Al/I₂ cell in water solution reduced during discharging process gradually, while the resistance of the Al/I₂ cell in the acetonitrile solution increased during discharging process. This could be due to the formation of a layer of amorphous AlI₃ on the surface of aluminum anode, which was confirmed by the scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and selected area electron diffraction measurements. An I⁻ ion conductor, LiI-(3-hydroxypropionitrile)₄ (LiI(HPN)₄) with 15 wt% SiO₂/I₂ cell was used as a solid electrolyte sandwiched between Al and I₂ electrode to assemble the solid-state Al-I₂ cell for further clarifying the transport mechanism. Our results demonstrated that the transport mechanism of Al-I₂ cell in the water may be involved in both cation and anion transport mechanism, but in non-aqueous solution, it may be involved in cation transport mechanism.     

Effects of Gas Composition on Highly Efficient Surface Modification of Multi-Walled Carbon Nanotubes by Cation Treatment

High incident energy hydrogen and/or oxygen cations are generated by electron cyclotron resonance system, and then used to highly efficiently modify multi-walled carbon nanotubes (MWCNTs). The effects of various H₂/O₂ gas compositions on the modification process are studied. A systematic characterization method utilizing a combination of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, Raman spectroscopy, and thermogravimetric analysis (TGA) is used to evaluate the effects of various H₂/O₂ gas compositions on MWCNT functionalization. The Raman results show that the I _D/I _G ratio is directly affected by H₂ concentration in gas mixture, and the treatment applying a H₂/O₂ gas mixture with ratio of 40/10 (sccm/sccm) can yield the nanotubes with the highest I _D/I _G ratio (1.27). The XPS results suggest that the gas mixture with ratio of 25/25 (sccm/sccm) is most effective in introducing oxygen-containing functional groups and reducing amorphous carbon. The TGA suggests that the structural change of the treated nanotubes is marginal by this method with any gas condition.     

Preparation of C/CMS composite membranes derived from Poly(furfuryl alcohol) polymerized by iodine catalyst

C/CMS composite membranes derived from poly(furfuryl alcohol) (PFA) polymerized by iodine catalyst were prepared. Gas separation performance was investigated by molecular probe study with pure gases (H₂, CO₂, O₂, N₂, and CH₄) at 25 °C. The pyrolysis behaviour of PFA was studied by TG and DTG. The surface morphology of C/CMS composite membranes was observed by SEM and HRTEM. The results show a C/CMS composite membrane with uniform and defect-free thin top layer can be prepared by the PFA liquid in only one coating step. The C/CMS composite membranes have excellent gas separation properties for the gas pairs such as H₂/N₂, CO₂/N₂, O₂/N₂ and CO₂/CH₄, the permselectivities for above gas pairs in same sequence were 124.72, 12.74, 9.12 and 15.91 respectively. Compared to carbon membranes derived from PFA polymerized by acid catalyst, the carbon membranes obtained from PFA polymerized by iodine catalyst have slightly lower permselectivity, but higher permeance.