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Manganese oxide with active surface sites can experience superior catalytic activity. MnO2 nanoparticles, of 11.4 nm particle size, were developed. Nitrocellulose (NC) was adopted as an energetic binder. Colloidal MnO2/Al nanothermite particles were integrated into the NC matrix via the co-precipitation technique. Nanothermite particles experienced an increase in NC decomposition enthalpy by 150% as well as enhanced reaction propagation index by 261%. A kinetic study demonstrated that nanothermite particles experienced a drastic decrease in NC activation energy by – 42 and – 40 kJ · mol−1 using Kissinger and KAS models, respectively. Novel energetic nanocomposite with superior combustion enthalpy, propagation index, and the activation energy was developed. [ABSTRACT FROM AUTHOR]

HMX is one of the most powerful energetic materials; however, HMX experience low sensitivity and high activation energy. Whereas ferric oxide particles can act as catalyst for HMX decomposition with change in its decomposition kinetics from C-N bond cleavage to hydrogen atom abstraction; ferric oxide can induce vigorous thermite reaction with aluminum particles. Consequently, thermite particles can catalyze HMX decomposition, and enhance its decomposition enthalpy. This study reports on the fabrication and of ferric oxide nanoparticles of 5 nm particle size. Ferric oxide NPs and aluminum nanoplates of 100 nm were effectively integrated into HMX via co-precipitation technique. Elemental mapping was performed using EDAX detector; uniform dispersion of nanothermite particles was confirmed. Nanothermite particles experienced enhanced HMX decomposition enthalpy by 53%, with decrease in decomposition temperature by 13°C. The impact of nanothermite particles on HMX kinetic decomposition was evaluated using two different analysis models including differential isoconversional method of model-free Friedman analysis, and integral isoconversional method of Ozawa. Thermite nanoparticles demonstrated drastic decrease in HMX activation energy by 24 and 30% using Friedman and Ozawa models, respectively. The developed colloidal nanothermite particles demonstrated superior catalytic effect with enhanced decomposition enthalpy. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) is one of the most common biocompatible material with high phosphorous content (18.5 wt %). HA is thermally stable compound that requires high temperature to decompose; upon decomposition active phosphorus can offer enhanced thermal signature for effective countermeasure of infrared missiles. High reaction temperature can be accomplished via high energy density materials such as nanothermites. This study reports on the facile synthesis of Fe2O3 nanoparticles (5 nm average particle size) and HA nanoplates (530 nm length, 140 nm width) using hydrothermal synthesis. Whereas ferric oxide was employed for nanothermite reactions, HA was employed as phosphorous source material. The effect of developed nanomaterials on thermal signature of traditional Magnesium/Teflon/Viton (MTV) decoy flare was evaluated using Arc-Optics IR spectrometer (1–6 µm). Whereas Fe2O3 (8 wt %) offered enhanced average intensity value by 67%; synergism between HA and Fe2O3 particles offered enhanced spectral performance by 97%. Key radiometric performance parameter is the relative intensity ratio Ɵ(Ɵ = Iα/ Iβ); synergism between HA and Fe2O3 offered superior radiometric performance with Ɵ value of 0.59; this value is similar to aircraft value. This novel spectral performance shaded the light on HA as novel phosphorus material for advanced infrared countermeasure flares. [ABSTRACT FROM AUTHOR]

Nanothermites (metal oxide/metal) can offer tremendously exothermic self sustained reactions. CuO is one of the most effective oxidizers for naonothermite applications. This study reports on two prospectives for the manufacture of CuO nanoparticles. Colloidal CuO particles of 15 nm particle size were developed using hydrothermal synthesis technique. Multiwalled carbon nanotubes (MWCNTs) with surface are 700m²/g was employed as a substrate for synthesis of CuO-coated MWCNTs using electroless plating. On the other hand, aluminium particles with combustion heat of 32000 J/g is of interest as high energy density material. The impact of stoichiometric nanothermite particles (CuO/Al & Cuo-coated MWCNTs/Al) on shock wave strength of Al/TNT nanocomposite was evaluated using ballistic mortar test. While CuO-coated MWCNTs decreased the shock wave strength by 15%; colloidal CuO enhanced the shock wave strength by 30%. The superior performance of colloidal CuO particles was correlated to their steric stabilization with employed organic solvent. This is the first time ever to report on fabrication, isolation, and integration of stablilized colloidal nanothermite particles into energetic matrix where intimate mixing between oxidizer and metal fuel could be achieved. [ABSTRACT FROM AUTHOR]

Ultrasensitive and low-cost detection means for immediate recognition of peroxide explosive compounds such as triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) have attracted tremendous attention due to their great significance in home land security. Metal hydrogen bronzes are promising materials for instant detection and neutralization of hazardous peroxides. This study reports on the sustainable fabrication of colloidal molybdenum oxide MoO 3 nanorods. Nanoscopic colloidal molybdenum hydrogen bronze (MHB) were evolved from synthesized MoO 3 via acidic hydrothermal treatment. Colloidal MHB particles with dark blue colour demonstrated complete change in surface properties from hydrophilic to hydrophobic; they demonstrated effective phase transfer from aqueous phase to organic phase. This novel reducing agent did not only offer neutralization of hazardous peroxides but also demonstrated an instant detection of such compounds with colour disappearance. Furthermore, MHB can act as a desensitizer for different hazardous materials by shuttling reactive hydrogen ions rendering them into non-explosive compounds. [ABSTRACT FROM AUTHOR]

One of the great impetus of nanotechnology on energetic materials is the achievement of nanothermites (metal-oxide/metal) which are characterized by massive heat output. Yet, full exploitation of super-thermites in highly energetic systems has not been achieved. This manuscript reports on the sustainable fabrication of colloidal Fe 2 O 3 and CuO nanoparticles for thermite applications. TEM micrographs demonstrated mono-dispersed Fe 2 O 3 and CuO with an average particle size of 3 and 15 nm respectively. XRD diffractograms demonstrated highly crystalline materials. SEM micrographs demonstrated a great tendency of the developed oxides to aggregate over drying process. The effective integration and dispersion of mono-dispersed colloidal thermite particles into energetic systems are vital for enhanced performance. Aluminum is of interest as highly energetic metal fuel. In this paper, synthesized Fe 2 O 3 and CuO nanoparticles were re-dispersed in isopropyl alcohol (IPA) with aluminum nanoparticles using ultrasonic prope homogenizer. The colloidal thermite peraticles can be intgegrated into highly energetic system for subsequent nanocomposite development. Thanks to stabilization of colloidal CuO nanoparticles in IPA which could offer intimate mixing between oxidizer and metal fuel. The stabilization mechanism of CuO in IPA was correlated to steric stabilization with solvent molecules. This approach eliminated nanoparticle drying and the re-dispersion of dry aggregates into energetic materials. This manuscript shaded the light on the real development of colloidal thermite mixtures and their integration into highly energetic systems. [ABSTRACT FROM AUTHOR]

A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180–240 °C to ensure DDSA ring opening and binding to titania nanoparticles. Organic-modified titania demonstrated complete change in surface properties from hydrophilic to hydrophobic and exhibited phase transfer from the aqueous phase to the organic phase. Exclusive surface modification in the reactor was found to be an effective approach; it demonstrated surfactant loading level 2.2 times that of post synthesis surface modification. Titania was also stabilized in aqueous media using poly acrylic acid (PAA) as polar polymeric dispersant. PAA-titania nanoparticles demonstrated a durable amorphous polymeric layer of 2 nm thickness. This manuscript revealed the state of the art for the real development of stable colloidal mono-dispersed particles with controlled surface properties. [ABSTRACT FROM AUTHOR]

Inorganic hydroxides represent more than 50% of flame retardants (FRs) sold globally. This is due to their low cost, low toxicity, and minimum corrosivity. Aluminium tri-hydroxide (ATH) is the largest FR in use. This paper reports on a novel continuous flow fabrication of nanoscopic ATH with consistent product quality. TEM micrographs demonstrated nanoplate structure with 25 nm size. XRD diffractogram revealed highly pure crystalline structure free from defects and any interfering substances. The made-up ATH has the potential to deliver a flame retardant action (heat sink action) to the hosting polymer by absorbing heat, releasing water, and forming a protective oxide layer (Al 2 O 3 ). This oxide layer can prevent further polymer degradation. The effectiveness of ATH heat sink action was evaluated with thermal analysis techniques including TGA and DSC. The phase transition of ATH to corresponding oxides during its endothermic decomposition was verified with XRD. The synergism between the ATH heat sink and intumescent action (provoked with a phosphorous-based FR agent known as AP750) was employed to develop self-extinguishing multi-component epoxy nanocomposite. The developed nanocomposite was able to resist direct flame source at 1700 °C; it demonstrated superior flammability performance using cone calorimeter testing. The peak heat released was decreased by 58%, and the time to peak heat released was extended by 35%. The synergism between ATH and AP750 was ascribed to the ability of the protective oxide layer (Al 2 O 3 ) (resulted from ATH decomposition) to crosslink the phosphoric acid chains (resulted from AP750 decomposition) and to form aluminium phosphate (AlPO 4 ). This catalytic action was demonstrated by conducting XRD of the developed char layer. [ABSTRACT FROM AUTHOR]

The particle size of magnesium di-hydroxide (MDH) was reported to have a significant impact on its flammability performance. Consequently, there have been many classical trials to produce ultra fine MDH for polymer flame retardancy. This paper reports on a novel continuous flow hydrothermal method for the instant synthesis of MDH nanoparticles. The hydrothermal conditions including: temperature, pressure, and flow rate were precisely controlled to achieve consistent product quality. MDH nanorods of 120 nm length and 20 nm diameters were reported by TEM. The tailored MDH crystalline phase and its phase transition with temperature (during its endothermic heat sink action) were investigated with XRD. The effectiveness of MDH as an endothermic heat sink material was evaluated by TGA and DSC. MDH was surface modified with organic polymeric surfactant in a continuous manner via post synthesis surface modification approach. Organic modified MDH exhibited complete change in surface properties and the nanoparticles were harvested from water phase to organic phase. Organic modified MDH exhibited smaller particle size with an increase in specific surface area and surface porosity compared with uncoated MDH. The synergism between MDH and an intumescent flame retardant (FR) agent commercially known as Exolit AP750 was investigated in order to achieve self extinguish multi-component epoxy nanocomposite at 10 wt.% total solid loading. This is the first trial to synthesize and to functionalize ultra fine MDH continually; this approach might extend MDH usage as a clean and nontoxic FR agent that can be effectively surface modified. Therefore, enhanced flammability performance can be achieved at low solid loading level. [ABSTRACT FROM AUTHOR]

One of the significant impacts of nanotechnology on polymeric material ' s flammability is the achievement of polymer nanocomposites (PNCs). Layered double hydroxide (LDH) is one of the most promising synthetic clays for PNC fabrication. A novel continuous flow method for LDH synthesis via controlled hydrothermal conditions has been recently reported. This paper reports on fine tuning surface chemistry of LDH via surface modification with different surfactants in a continuous flow manner. LDH surface properties were changed from hydrophilic to hydrophobic, and the developed particles were harvested from the water phase to the organic phase. The synthesized LDH has the potential to deliver a flame retardant action (as a heat sink material) to the hosting polymer by absorbing heat, releasing water, and forming a protective oxide layer which can prevent further degradation. The heat sink action of synthesized LDH was evaluated with thermal analysis techniques. The phase transition of LDH to corresponding oxides during its endothermic decomposition was investigated with XRD. This is the first time LDH has been surface modified continuously and its FR action as well as its phase transition has been examined. This paper might open the route for LDH as nano-filler with flame retardant properties. Surface modification was reported to enhance the dispersion characteristics of inorganic nanoparticles into the hosting polymer. Therefore enhanced flammability performance can be achieved at low solid loading level. [ABSTRACT FROM AUTHOR]

There are well known problems with the dispersion of inorganic nanoadditives into organic medium as they tend to aggregate and agglomerate, therefore the particles act like micron sized particles rather than nanoparticle scale. In this paper, we investigated the differences between dispersing dry and colloidal TiO 2 nanoparticles into epoxy resin. The dry TiO 2 was commercially obtained P25 and freeze dried TiO 2 from continuous hydrothermal synthesis (CHS). The colloidal TiO 2 was produced from CHS but without a drying stage. Specific parameters including loading level (1-30 wt.%), mechanical mixing (2–60 min), polymer heating (25–80 °C), and dry and wet addition were investigated. The nanoparticle dispersion was investigated with SEM and quantified by using Labview image analysis (National Instruments), in order to quantify the characteristic aggregate dimensions such as perimeter, maximum feret diameter, and size. TiO 2 nanoparticles were formulated and surface modified with dodecenyl succinic anhydride (DDSA) by using CHS technique. Online phase transfer was used to produce colloidal DDSA–titania dispersed in toluene which could then be directly integrated into epoxy resin. This approach showed enhanced nanoparticle dispersion (nanoscale dispersion) with minimum aggregation compared with the dispersion of dry nanoparticles. Furthermore, this approach enabled the elimination of nanoparticle freeze drying and the redispersion of aggregated dry nanoparticles into polymeric matrix. [ABSTRACT FROM AUTHOR]

This study reports on a new perspective in continuous hydrothermal fabrication of highly crystalline nano-catalysts including Mg-Al layered double hydroxide and titanium dioxide. Nano-colloidal catalysts, with consistent product quality were manufactured continually; a set of characterization techniques including XRD, TEM, SEM, and N 2 adsorption-desorption were employed. Mg-Al layered double hydroxide and titanium dioxide demonstrated surface area of 275.7 and 40.2 m 2 /g respectively. The photocatalytic activity of colloidal Mg-Al layered double hydroxide and titanium dioxide were evaluated by degradation of methylene blue under UV-light irradiation and compared to commercial photocatalyst (Zinc oxide). The degradation rate of methylene blue reached 90%, 73%, and 52% for Mg-Al layered double hydroxide, TiO 2 , and ZnO respectively, after 120 min irradiation time. The increase in layered double hydroxide content from 25 to 100 mg offered an increase in degradation efficiency from 67% to 90%. Under optimal conditions of Mg-Al layered double hydroxide content, H 2 O 2 concentrations, and irradiation time; 100% degradation of methylene blue was achieved. This superior photocatalytic activity of Mg-Al layered double hydroxide compared with TiO 2 and ZnO was ascribed to its high surface area and pore volume, enhanced light absorption, its excellent ability to capture organic species and finally efficient charge separation and transfer. This manuscript shaded the light on instant manufacture of Mg-Al layered double hydroxide and its effectiveness as a novel photocatalyst for wastewater treatment. [ABSTRACT FROM AUTHOR]