Effect of Nano‐Copper Oxide and Copper Chromite on the Thermal Decomposition of Ammonium Perchlorate

The catalytic effect on the thermal decomposition behavior of ammonium perchlorate (AP) of p‐type nano‐CuO and CuCr₂O₄ synthesized by an electrochemical method has been investigated using differential scanning calorimetry as a function of catalyst concentration. The nano‐copper chromite (CuCr₂O₄) showed best catalytic effects as compared to nano‐cupric oxide (CuO) in lowering the high temperature decomposition by 118 °C at 2 wt.‐%. High heat releases of 5.430 and 3.921 kJ g⁻¹ were observed in the presence of nano‐CuO and CuCr₂O₄, respectively. The kinetic parameters were evaluated using the Kissinger method. The decrease in the activation energy and the increase in the rate constant for both the oxides confirmed the enhancement in catalytic activity of AP. A mechanism based on an electron transfer process has also been proposed for AP in the presence of nano‐metal oxides.     

Nanocrystalline Transition Metal Oxides as Catalysts in the Thermal Decomposition of Ammonium Perchlorate

Nanocrystalline transition metal oxides (NTMOs) have been successfully prepared by three different methods: novel quick precipitation method (Cr₂O₃ and Fe₂O₃); surfactant mediated method (CuO), and reduction of metal complexes with hydrazine as reducing agent (Mn₂O₃). The nano particles have been characterized by X‐ray diffraction (XRD) which shows an average particle diameter of 35–54 nm. Their catalytic activity was measured in the thermal decomposition of ammonium perchlorate (AP). AP decomposition undergoes a two step process where the addition of metal oxide nanocrystals led to a shifting of the high temperature decomposition peak toward lower temperature. The kinetics of the thermal decomposition of AP and catalyzed AP has also been evaluated using model fitting and isoconversional method.     

Evaluation of Nano‐Co3O4 in HTPB‐Based Composite Propellant Formulations

Different propellant compositions were prepared by incorporating nano‐sized cobalt oxide from 0.25 % to 1 % in HTPB/AP/Al‐based composite propellant formulations with 86 % solid loading. The effects on viscosity build‐up, thermal, mechanical and ballistic properties were studied. The findings revealed that by increasing the percentage of nano‐Co₃O₄ in the composition, the end of mix viscosity, the modulus and the tensile strength increased, whereas the elongation decreased accordingly. The thermal property data envisaged a reduction in the decomposition temperature of ammonium perchlorate (AP) as well as formulations based on AP. The ballistic property data revealed an enhanced burning rate from 6.11 mm s⁻¹ (reference composition) to 8.99 mm s⁻¹ at 6.86 MPa and a marginal increase in pressure exponent from 0.35 (reference composition) to 0.42 with 1 % nano‐cobalt oxide.     

Catalytic Effect of Two Shapes of Nano‐Fe2O3 on Hexanitrohexaazaisowurtzitane Using a Non‐Isothermal Decomposition Kinetic Method

Nanosized Fe₂O₃ particles (nano‐Fe₂O₃) with two shapes (tetrakaidecahedral and grainy) were synthesized by hydrothermal methods. The morphologies and structures were characterized using a combination of experimental techniques including X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Two composites containing CL‐20 (hexanitrohexaazaisowurtzitane, HNIW) and tetrakaidecahedral nano‐Fe₂O₃ [nmT‐Fe₂O₃/CL‐20] or grainy nano‐Fe₂O₃/CL‐20 (nmG‐Fe₂O₃/CL‐20) were prepared. The thermal behaviors of the two composites and pure CL‐20 were investigated using differential scanning calorimetry (DSC). Non‐isothermal decomposition kinetic parameters and the thermal decomposition mechanism of the two composites and CL‐20 were obtained. The apparent activation energy (E_a) of the main thermal decomposition reaction of CL‐20, nmT‐Fe₂O₃/CL‐20 and nmG‐Fe₂O₃/CL‐20 are 181.94, 179.17, and 176.18 kJ mol⁻¹, respectively. The thermal decomposition mechanism of CL‐20 as well as nmT‐Fe₂O₃/CL‐20 was controlled by the Avrami‐Erofeev equation (n=2/5) assumed as random nucleation and subsequent growth, while, the reaction mechanism of the composite nmG‐Fe₂O₃/CL‐20 was controlled by the Mample Power law (n=1/2). The reason for this difference may be due to the different morphology and particle size of the two nano‐Fe₂O₃ particles.     

Iron Nanoparticle Additives as Burning Rate Enhancers in AP/HTPB Composite Propellants

Burning rate measurements were carried out for ammonium perchlorate/hydroxyl‐terminated polybutadiene (AP/HTPB) composite propellants with iron (Fe) nanoparticles as additives. Experiments were performed in a strand burner at pressures from 0.2 to 10 MPa for propellants containing approximately 80 % AP and Fe nanoparticles (60–80 nm) at concentration from 0 to 3 % by weight. It was found that the addition of 1 % Fe nanoparticles increased burning rate by factors of 1.2–1.6. Because Fe nanoparticles are oxidized on the surface and have high surface‐to‐volume ratio, they provide a large surface area of Fe₂O₃ for AP thermal decomposition catalysis at the burning propellant surface, while also providing added energy release due to the oxidation of nanoparticle sub‐shell Fe. The increase in burning rate due to Fe nanoparticle content is similar to the increase in burning rate caused by the addition of iron oxide (Fe₂O₃) particles observed in prior literature.     

A Study on the Mechanism of the Thermal Decomposition of Ammonium Perchlorate

The thermal decomposition of ammonium perchlorate in the presence of potassium chloride and chromium (III) oxide was investigated using K³⁶ Cl and⁵¹ Cr₂ O₃ to elucidate the reaction mechanism. Two simultaneous routes are suggested for the decomposition. It was found that double decomposition in vacuo between potassium chloride and ammonium perchlorate does not result in the formation of potassium perchlorate. Chromium (III) oxide was not oxidized by ammonium perchlorate, but oxidation to the hexavalent state took place when potassium chloride was present.     

Nanocobaltite: Preparation,Characterization, and their Catalytic Activity

Mixed transition metal oxides (MTMO) nanoparticles of 3rd‐series (NiCo₂O₄, CuCo₂O₄, and ZnCo₂O₄) were prepared by a co‐precipitation method. These were characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The particle size was found to be in the order of 53.0, 43.4, and 21.2 nm, respectively. The thermolysis of ammonium perchlorate (AP), AP‐HTPB (hydroxyterminated polybutadiene) composite solid propellants (CSPs), and HTPB was found to be catalyzed with MTMOs and the burning rate of CSPs was also enhanced. TG and ignition delay study demonstrated that the higher temperature decomposition (HTD) of AP is catalyzed enormously by these catalysts and CuCo₂O₄ is the best candidate.     

Effect of Fe2O3 in Fe2O3/AP Composite Particles on Thermal Decomposition of AP and on Burning Rate of the Composite Propellant

A technique of composite processing of Fe₂O₃ and ammonium perchlorate (AP) was employed in making the propellant. The effects of composite processing of Fe₂O₃ on catalytic activity, on the thermal decomposition of AP, and on the burning rate of the composite propellant were investigated in this paper. Fe₂O₃/AP composite particles were prepared by a novel solvent‐nonsolvent method. The results show that AP is successfully coated on the surface of Fe₂O₃. Composite processing of Fe₂O₃ and AP can improve the catalytic activity of Fe₂O₃. Fe₂O₃ exhibits better catalytic effect with increasing Fe₂O₃ content. The larger interface between Fe₂O₃ and AP and lower density of composite propellant (with the added Fe₂O₃/AP composite particles) are responsible for the enhancement of the catalytic activity of Fe₂O₃.     

Plateau Burning Characteristics of AP Based Azide Composite Propellants

The site and mechanism by which iron oxide catalyst acted to enhance burning rate and produced plateau burning behavior at high pressure was studied. The condensed phase chemistry study was conducted by isothermal thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and rapid-scan FTIR spectroscopic technique. Uncatalyzed ammonium perchlorate (AP) based azide composite propellant showed unstable combustion at relatively lower pressure region. The heat balance at the buring surface would be unstable at these pressures. However, iron oxide altered the burning property of the propellant and enhanced the burning rate with the plateau-mesa burning characteristics. Such pressure insensitiveness of the burning rate indicated that the condensed phase chemistry played important role in the catalytic mechanism of action. According to the microrocket motor tests, physical effect, melted fuel binder covered the AP particles and prevented the further decomposition of AP, had not affected the plateau burning. Fe₂O₃ was more effective on the burning rate augmentation than Fe₃O₄. However, the pressure exponent of the burning rate point of view Fe₃O₄ was favored catalyst to the propellant used here.     

Fabrication of Fe3O4/PLLA composites for use in bone tissue engineering

The aim of this study was to incorporate nanoscale Fe₃O₄ particles into a poly‐l ‐lactide (PLLA) matrix to fabricate a magnetic and biodegradable composite. The physical and osteogenic functions of this material were tested. Injection molding was used to fabricate four nano‐Fe₃O₄/PLLA composites with Fe₃O₄ mix ratios of 0%, 20%, 30%, and 40% (w/w). X‐ray diffraction and hysteresis loop tests were performed to evaluate the physical properties of the nano‐Fe₃O₄/PLLA composites. Tensile strength tests showed that the progressive addition of nano‐Fe₃O₄ particles to the PLLA matrix results in higher elastic modulus and lower tensile strength. Images from scanning electron microscopy demonstrated that osteoblasts cultured on the 20% nano‐Fe₃O₄/PLLA surface exhibited abundant filaments, which are a morphologic characteristic of osteoblastic differentiation. These results suggest that the 20% nano‐Fe₃O₄/PLLA composite used in this study has the potential for future tissue engineering applications. POLYM. COMPOS., 38:2881–2888, 2017. © 2016 Society of Plastics Engineers     

Synergistic effect of metal oxides on the flame retardancy and thermal degradation of novel intumescent flame‐retardant thermoplastic polyurethanes

The synergistic effects of some metal oxides on novel intumescent flame retardant (IFR)–thermoplastic polyurethane (TPU) composites were evaluated by limiting oxygen index (LOI), vertical burning test (UL‐94), thermogravimetric analysis (TGA), cone calorimetry, and scanning electron microscopy. The experimental data indicated that the metal oxides enhanced the LOI value and restricted the dropping of the composites. The IFR–TPU composites passed the UL‐94 V‐0 rating test (1.6 mm) in the presence of magnesium oxide (MgO) and ferric oxide (Fe₂O₃) at 35 wt % IFR loading, whereas only the MgO‐containing IFR–TPU composite reached a UL‐94 V‐0 rating at 30 wt % IFR loading. The TGA results show that the metal oxides had different effects on the process of thermal degradation of the IFR–TPU compositions. MgO easily reacted with polyphosphoric acid generated by the decomposition of ammonium polyphosphate (APP) to produce magnesium phosphate. MgO and Fe₂O₃ showed low flammability and smoke emission due to peak heat release rate, peak smoke production rate, total heat release, and total smoke production (TSP). However, zinc oxide brought an increase in the smoke production rate and TSP values. Among the metal oxides, MgO provided an impressive promotion on the LOI value. The alkaline metal oxide MgO more easily reacted with APP in IFRs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Burning Characteristics and Thermochemical Behavior of AP/HTPB Composite Propellant Using Coarse and Fine AP Particles

The burning rate of AP/HTPB composite propellant increases with increasing AP content and with decreasing AP size. In addition, the burning rate can be enhanced with the addition of Fe₂O₃. The burning characteristics and thermal decomposition behavior of AP/HTPB composite propellant using coarse and fine AP particles with and without Fe₂O₃ at various AP contents were investigated to obtain an exhaustive set of data. As the AP content decreased, the burning rate decreased and the propellants containing less than a certain AP content self‐quenched or did not ignite. The self‐quenched combustion began at both lower and higher pressures. The lower limit of AP content to burn the propellant with coarse AP was lower than that with fine AP. The lower limit of AP content to burn was decreased by the addition of Fe₂O₃. The thermal decomposition behavior of propellants prepared with 20–80 % AP was investigated. The decrease in the peak temperature of the exothermic decomposition suggested an increased burning rate. However, a quantitative relationship between the thermochemical behavior and the burning characteristics, such as the burning rate and the lower limit of AP content to burn, could not be determined.     

Synergistic effects of nano‐Mn0.4Zn0.6Fe2O4 on intumescent flame‐retarded polypropylene

The melamine salt of 5,5‐dimethyl‐1,3,2‐dioxaphos‐phorinane‐2‐oxide‐2‐hydroxide (IFR100) was used as an intumescent flame retardant in flame‐retarded polypropylene (PP). As a synergistic agent, nano‐Mn_0.4Zn_0.6Fe₂O₄ was incorporated into the PP/IFR100 composite at different proportions. The synergistic effects of nano‐Mn_0.4Zn_0.6Fe₂O₄ were studied by the limiting oxygen index (LOI) test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD). The synergistic effect of the nano‐Mn_0.4Zn_0.6Fe₂O₄ additive with IFR100 was clearly observed by LOI. The TGA results showed that nano‐Mn_0.4Zn_0.6Fe₂O₄ improved the thermal stability of the PP/IFR100 system above 400°C. On the basis of the FTIR and XRD results, it was evident that nano‐Mn_0.4Zn_0.6Fe₂O₄ efficiently promoted the formation of a charred layer containing phosphocarbonaceous structures. The SEM micrographs indicated that nano‐Mn_0.4Zn_0.6Fe₂O₄ strengthened the structure of the char layer remaining after combustion. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers     

Fe3O4@mesoporouspolyaniline: A Highly Efficient and Magnetically Separable Catalyst for Cross‐Coupling of Aryl Chlorides and Phenols

A high surface, magnetic Fe₃O₄@mesoporouspolyaniline core‐shell nanocomposite was synthesized from magnetic iron oxide (Fe₃O₄) nanoparticles and mesoporouspolyaniline (mPANI). The novel porous magnetic Fe₃O₄ was obtained by solvothermal method under sealed pressure reactor at high temperature to achieve high surface area. The mesoporouspolyaniline shell was synthesized by in situ surface polymerization onto porous magnetic Fe₃O₄ in the presence of polyvinylpyrrolidone (PVP) and sodium dodecylbenzenesulfonate (SDBS), as a linker and structure‐directing agent, through ‘blackberry nanostructures’ assembly. The material composition, stoichiometric ratio and reaction conditions play vital roles in the synthesis of these nanostructures as confirmed by variety of characterization techniques. The role of the mesoporouspolyaniline shell is to stabilize the porous magnetic Fe₃O₄ nanoparticles, and provide direct access to the core Fe₃O₄ nanoparticles. The catalytic activity of magnetic Fe₃O₄@mesoporousPANI nanocomposite was evaluated in the cross‐coupling of aryl chlorides and phenols.     

Chemical and Textural Characterization of Iron Oxide Nanoparticles and Their Effect on the Thermal Decomposition of Ammonium Perchlorate

Metal oxide nanoparticles have been used as burning rate catalysts for ammonium perchlorate (AP) decomposition in composite solid propellants. Though most papers point to the efficiency of different sizes, shapes and compositions, the texture of the agglomerated particles plays an important role in the catalytic efficiency, but this aspect is not always discussed. In this paper, iron oxide and composite iron oxide/silica powders were synthesized in microemulsion systems and their effect on the decomposition of AP was investigated. X‐ray diffraction (XRD) analysis and Fourier transformed infrared spectroscopy (FT‐IR) showed that the synthesized powders have an amorphous to nanocrystalline pattern, with Fe₂O₃ composition. The use of different FT‐IR spectroscopic techniques – transmission, diffuse reflectance (DRIFT) and universal attenuated total reflectance (UATR) – allied to electron microscopy analysis allowed the characterization of the samples’ surface, indicating that silicon oxide forms a thick matrix that covers the iron oxide nanoparticles. Adsorption of N₂, light scattering and electron microscopy pointed that all samples are formed by mesoporous agglomerated nanoparticles containing micropores indicating that silicon oxide forms a thick matrix that covers the iron oxide nanoparticles. Adsorption of N₂, pointed that all samples show different microstructures and light scattering indicated results refer to agglomerated particles. Finally, the catalytic effect of the samples on the decomposition of AP was evaluated by thermogravimetric analysis coupled to differential thermal analysis (TG/DTA), showing that only the high temperature decomposition step of AP was affected by the catalyst, shifting to lower temperatures the higher the surface area of the synthesized iron oxide sample, regardless of the presence of the silica matrix.     

Statistical Optimization of the Biodiesel Production Process Using a Magnetic Core‐Mesoporous Shell KOH/Fe3O4@γ‐Al2O3 Nanocatalyst

A magnetic core‐mesoporous shell KOH/Fe₃O₄@γ‐Al₂O₃ nanocatalyst was synthesized using the Fe₃O₄@γ‐Al₂O₃ core‐shell structure as support and KOH as active component. The prepared samples were characterized by X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FE‐SEM), energy‐dispersive X‐ray spectroscopy (EDS), Fourier transform infrared (FTIR), Brunauer‐Emmett‐Teller (BET), and vibrating sample magnetometry (VSM) techniques. Transesterification of canola oil to methyl esters (biodiesel) in the presence of the magnetic core‐mesoporous shell KOH/Fe₃O₄@γ‐Al₂O₃ nanocatalyst was investigated. Response surface methodology (RSM) based on the Box‐Behnken design (BBD) was employed to optimize the influence of important operating variables on the yield of biodiesel. A biodiesel yield of 97.4 % was achieved under optimum reaction conditions. There was an excellent agreement between experimental and predicted results.     

Bio‐Based Hybrid Magnetic Latex Particles Containing Encapsulated γ ‐Fe2O3 by Miniemulsion Copolymerization of Soybean Oil‐Acrylated Methyl Ester and Styrene

This work reports the use of acrylated fatty acid methyl ester (AFAME) as a biomonomer for the synthesis of bio‐based hybrid magnetic particles poly(styrene‐co‐AFAME)/γ‐Fe₂O₃ produced by miniemulsion polymerization. Poly(styrene‐co‐AFAME)/γ‐Fe₂O₃ can be tailored for use in various fields by varying the content of AFAME. The strategy employed is to encapsulate superparamagnetic iron oxide nanoparticles (SPIONs) as γ‐Fe₂O₃ into a styrene/AFAME‐based copolymer matrix. Raman spectroscopy is employed to ensure the formation of the SPIONs (γ‐Fe₂O₃) obtained by a co‐precipitation technique followed by oxidation of Fe₃O₄. The functionalization of SPIONs with oleic acid (OA) is carried out to increase the SPIONs–monomer affinity. The presence of OA on the surface of γ‐Fe₂O₃ is certified by identification of main absorption bands by fourier‐transform infrared spectroscopy (FTIR). Thermal analysis (differential thermogravimetry/differential thermo analysis and differential scanning calorimetry) results of poly(styrene‐co‐AFAME)/γ‐Fe₂O₃ show an increase in AFAME content leading to a lower copolymer glass transition temperature (T _g). Dynamic light scattering (DLS) measurements result in poly(styrene‐co‐AFAME)/γ‐Fe₂O₃ particles with diameter in the range of 100–150 nm. It is also observed by transmission electron microscopy (TEM) and cryo‐TEM techniques that γ‐Fe₂O₃ particles are successfully encapsulated into the poly(styrene‐co‐AFAME) matrix.     

Role of Additives in the Combustion of Ammonium Dinitramide

The thermal decomposition behavior and combustion characteristics of mixtures of ammonium dinitramide (ADN) with additives were studied. Micrometer‐sized particles of Al, Fe₂O₃, TiO₂, NiO, Cu(OH)NO₃, copper, CuO, and nanometer‐sized particles of aluminum (Alex) and CuO (nano‐CuO) were employed. The thermal decomposition was measured by TG‐DTA and DSC. The copper compounds and NiO lowered the onset temperature of ADN decomposition. The heat value of ADN with Alex was larger than that of pure ADN in closed conditions. The burning rates and temperature of the pure ADN and ADN/additives mixtures were measured. CuO and NiO enhance the burning rate, particularly at pressures lower than 1 MPa, because of the catalyzed decomposition in the condensed phase; the other additives lower the burning rate. This negative effect on the burning rate is explained based on the surface temperature measurements by a physicochemical mechanism, which involves a chemical reaction, a phase change of the ammonium nitrate, and the blown‐off droplets of the condensed phase.     

Synthesis and optimization of PES‐Fe3O4 mixed matrix nanocomposite membrane: Application studies in water purification

A mixed matrix nanocomposite membrane comprising of polyethersulfone (PES) and nano Fe₃O₄ particles was synthesised with an aim to develop a membrane with superior ability to high water flux while maintaining salt rejection efficiency. The study focused on optimizing the effect of different percentages of nano Fe₃O₄ particles addition on the membrane pure water flux, and rejection of both the NaCl and MgSO₄. The results showed that the PES nanocomposite membrane with 15% Fe₃O₄ exhibited the highest pure water flux, while the highest rejection of NaCl and MgSO₄ belonged to the PES‐10% Fe₃O₄. The rejection sequence of PES‐10% Fe₃O₄ membrane was 68% and 82%, respectively. Also it was observed that nano Fe₃O₄ particles improved membrane hydrophilicity, and helped to construct a membrane with desire surface and cross‐section morphology. POLYM. COMPOS., 34:1870–1877, 2013. © 2013 Society of Plastics Engineers     

Burning‐rate enhancement of a high‐energy rocket composite solid propellant based on ferrocene‐grafted hydroxyl‐terminated polybutadiene binder

Four different samples of ferrocene‐grafted hydroxyl‐terminated polybutadiene (Fc‐HTPB), containing 0.20, 0.52, 0.90, and 1.50 wt % iron, were synthesized by the Friedel–Crafts alkylation of ferrocene with hydroxyl‐terminated polybutadiene (HTPB) in the presence of AlCl₃ as a (Lewis acid) catalyst. The effects of the reaction conditions on the extent of ferrocene substitution were investigated. The Fc‐HTPBs were characterized by IR, ultraviolet–visible, ¹H‐NMR, and ¹³C‐NMR spectra. The iron content and number of hydroxyl groups were estimated, and the properties, including thermal degradation, viscosity, and propellant burning rates (BRs), were also studied. The thermogravimetric data indicated two major weight loss stages around 395 and 500°C. These two weight losses were due to the depolymerization and decomposition of the cyclized product, respectively, with increasing temperature. The Fc‐HTPB was cured with toluene diisocyanate and isophorone diisocyanate separately with butanediol–trimethylolpropane crosslinker to study their mechanical properties. Better mechanical properties were obtained for the gumstock of Fc‐HTPB polyurethanes with higher NCO/OH ratios. The BRs of the ammonium perchlorate (AP)‐based propellant compositions having these Fc‐HTPBs (without dilution) as a binder were much higher (8.66 mm/s) than those achieved with the HTPB/AP propellant (5.4 mm/s). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011