The Effect of Aminated Carbon Nanotube and Phosphorus Pentoxide on the Thermal Stability and Flame Retardant Properties of the Acrylonitrile–Butadiene–Styrene

Multi-walled carbon nanotubes (MWCNT) have been successfully functionalized with amino groups. In order to improve the thermal stability of the polymer nanocomposite, aminated-MWCNTs were added to acrylonitrile–butadiene–styrene (ABS). The influence of MWCNT and phosphorus pentoxide nanostructures on the flame retardancy of the ABS matrix was studied using UL-94 test. The results show that the MWCNT nanostructure can’t enhance the flame retardancy of the ABS matrix but synergism of MWCNT and P₂O₅ can effectively improve the flame retardancy of the nanocomposite.     

The Effect of Flower-Like Magnesium Hydroxide Nanostructure on the Thermal Stability of Cellulose Acetate and Acrylonitrile–Butadiene–Styrene

Flower-like magnesium hydroxide (Mg(OH)₂) nanostructures were synthesized via a simple hydrothermal reaction at relatively low temperature. The Mg(OH)₂ nanostructures were then added to acrylonitrile–butadiene–styrene (ABS) and cellulose acetate (CA) polymers. The effect of Mg(OH)₂ nanostructures on the thermal stability of the polymeric matrixes has been investigated. The thermal decomposition of the nanocomposites shifts towards higher temperature in the presence of the Mg(OH)₂. The enhancement of thermal stability of nanocomposites is due to endothermically decomposition of magnesium hydroxide that releases of water and dilutes combustible gases. Nanostructures and nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), UL-94 test and limiting oxygen index (LOI) analysis.     

Thermal analysis of the oxide–chloride systems GdCl3–Gd2O3 and GdCl3–KCl–Gd2O3

Journal of Thermal Analysis and Calorimetry - The thermal analysis of the oxide–chloride systems GdCl3–Gd2O3 and GdCl3–KCl–Gd2O3 with the Gd2O3 content up to...     

Effect of TiO2 Nanoparticles on Photochromism of WO3 Colloids

IntroductionWO3has received considerable attention becauseof its photochromic and electrochromic properties[1—10].Since the photochromic process of WO3can be com-pletely reversible by exposing it to oxygen,it has beenconsidered to be one of the most prom…     

Effect of ZnO on the interfacial bonding between Na2O–B2O3–SiO2 vitrified bond and diamond

Diamond composites were prepared by sintering diamond grains with low melting Na₂O–B₂O₃–SiO₂ vitrified bonds in air. The influence of ZnO on the wettability and flowing ability of Na₂O–B₂O₃–SiO₂ vitrified bonds was characterized by wetting angle, the interfacial bonding states between diamond grains and the vitrified bonds were observed by scanning electron microscope (SEM), and the micro-scale bonding mechanism in the interfaces was investigated by means of energy-dispersive spectrometer (EDS), Fourier transform infrared (FTIR) spectrometer and X-ray photoelectron spectroscopy (XPS). The experimental results showed that ZnO facilitated the dissociation of boron/silicon–oxygen polyhedra and the formation of larger amount of non-bridging oxygen in the glass network, which resulted in the increase of the vitrified bonds' wettability and the formation of –CO, –O–H and –C–H bonds on the surface of diamond grains. B and Si diffused from the vitrified bonds to the interface, and C–C, C–O, CO and C–B bond formed on the surface of sintered diamond grains during sintering process, by which the interfacial bonding between diamond grains and the vitrified bonds was strengthened.     

Effect of the Size of Polyacrylamide-Stabilized Palladium Nanoparticles Supported on γ-Fe2O3 on Their Catalytic Properties in the Hydrogenation of Phenylacetylene

Theoretical and Experimental Chemistry - Hydrogenation catalysts derived from palladium nanoparticles varying in size supported on maghemite (γ-Fe2O3) were obtained by varying the...     

The Thermal Synthesis of the ZnO–Bi2O3 Pigments

A zinc oxide pigment with an admixture of bismut oxide has been prepared as new yellow pigment for colouring of plastics and paints. The effect of the Bi₂ O₃ in the starting mixture on the colour hue of the pigment has been evaluated. The calcination conditions of the pigment synthesis have been established. The synthesis of these pigments was followed by thermal analysis using a derivatograph apparatus in our laboratory. The optimum conditions for the synthesis of pigments and the properties of the products have been estimated. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of nano-Al2O3 particles and of the Co concentration on the corrosion behavior of electrodeposited Ni–Co alloys

Incorporation of nano-Al₂O₃ particles into a Ni–Co alloy by electrodeposition influences the corrosion properties, morphology, and structure of the layers. The resistance against corrosion of Ni–Co/Al₂O₃ composite films deposited on stainless steel was investigated in a 0.1-M NaCl solution by potentiodynamic polarization. The presence of nanoparticles improves the corrosion resistance of Ni–Co/nano-Al₂O₃ deposits when compared to pure Ni–Co alloy. Moreover, by increasing the pH of the electrodeposition bath and the content of Co in the alloy, the resistance against corrosion is furthermore improved. The morphology of the deposits before and after their corrosion was analyzed by scanning electron microscopy. The presence of the embedded alumina particles in the Ni–Co alloys was one of the key factors that limited further propagation of corrosion on the metallic surface. Preferential corrosion attack, in the form of a pitting corrosion, was located mainly at the grain boundaries.     

Effect of Co60 γ-irradiation on the optical properties of thin films from the system GeSe3–Sb2Se3–ZnSe

Optical transmittance in the range from 200 nm to 1100 nm is measured for fresh and γ-irradiated thermally evaporated chalcogenide films of GeSe₃, Sb₂Se₃, ZnSe, (GeSe₃)₈₀(Sb₂Se₃)₂₀ and (GeSe₃)₇₀(Sb₂Se₃)₁₀(ZnSe)₂₀. The effect of ZnSe incorporation with both GeSe₃, Sb₂Se₃ results in amorphous γ-radiation sensitive (GeSe₃)₇₀(Sb₂Se₃)₁₀(ZnSe)₂₀ composition as obtained from the estimated optical parameters. Optical energy gap, E_g, for (GeSe₃)₇₀(Sb₂Se₃)₁₀(ZnSe)₂₀ film shows a noticeable decrease from 1.81 eV at 0 kGy to 1.52 eV at 690 kGy and conversely the corresponding band tail width, E_e, increases from 0.123 eV at 0 kGy to 0.138 eV at 690 kGy. By contrast, the estimated values of E_g and E_e for (GeSe₃)₈₀(Sb₂Se₃)₂₀ compositions, show no change with different γ-irradiation doses in the same range. The obtained results could be explained in terms of the band edge shift into the energy gap due to either the formation of localized states at the edges or weakening in the composition cohesive energy as reformation of new weaker bonds appear.     

Thermal and Structural Investigation of the Reaction Between 1,2-propanediol and Co(NO3)2⋅6H2O

The results of an investigation concerning there action between 1,2-propanediol and Co(NO₃)₂⋅ 6H₂O, leading to a complex containing the lactate anion (L) as ligand are presented. The obtained solid homopolynuclear coordination compound[Co₂(OH)₂L₂(H₂O)₂⋅0.5H₂O]_n, has been investigated by thermal analysis, electronic and IR spectroscopy and magnetic methods. Cobalt oxide obtained by thermal decomposition of this coordinative compound was characterized by IR and X-ray spectroscopy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synergistic cocatalytic effect of MoO3 and creatinine on Cu–Fenton reactions for efficient decomposition of H2O2

The key scientific problems with conventional Fenton reactions are the acidic pH dependence and low ROS production due to inefficient decomposition of H₂O₂. Although Cu–Fenton reactions can break the pH limitation, there is still an urgent need to improve the overall reaction efficiency, and thus broaden its applicability. Herein, we describe a synergistic strategy by introducing MoO₃ cocatalyst and creatinine (Cr) assistant to enhance the efficiency of Cu–Fenton reactions at near-neutral pH. In this strategy, Cu²⁺ interacts with Cr to form a complex (CuCr₂), which is then mainly linked to MoO₃ via the Cu²⁺ binding site (CuCr₂/MoO₃). Experimental and theoretical calculation results manifest that the CuCr₂/MoO₃ exhibits an excellent cocatalytic activity, which significantly facilitates the rate-limiting step of Cu–Fenton reactions, and enables the efficient decomposition of H₂O₂ for the generation of three reactive oxygen species (ROS, ?OH, ¹O₂, ?O₂^?). More significantly, this cocatalytic system with high oxidation activity can be applied for the detection of Cu²⁺ and ROS-based chemodynamic therapy (CDT), as well as sterilization of Escherichia coli. This study represents a new breakthrough in improving the efficiency of Fenton-based reactions with a facile and promising strategy, and drives great progress in practicality.     

The Effect of Platinum on Stability of the B2O3/TiO2-ZrO2 Catalyst for Beckmann Rearrangement of Cyclohexanone Oxime

It has been well illustrated that the rapid catalyst deactivation with time is the most serious limitation of vapor phase approach to the production of ε-caprolactam from cyclohexanone oxime (CHO) (Scheme 1), and is a common problem with all catalyst typ…     

Thermal properties and crystallization of BaO–MoO3–P2O5 glasses

Journal of Thermal Analysis and Calorimetry - The thermal behavior and crystallization of barium molybdate-phosphate glasses were studied in two compositional series, namely A:...     

Thermal properties of Na2O–P2O5–Fe2O3 polyphosphate glasses

Journal of Thermal Analysis and Calorimetry - Iron phosphate glasses are materials that can have many applications like durable matrixes in waste immobilization techniques, biomaterials,...     

Effect of zinc oxide on microhardness and sintering behavior of MgO–Al2O3–SiO2 glass–ceramic system

Glass–ceramic in the MgO–Al₂O₃–SiO₂ system with crystallization ability of gahnite (ZnO·Al₂O₃) and mullite were synthesized. It was found that the glass–ceramic containing gahnite phase had desirable mechanical behavior and reached to an acceptable hardness and density. The compositions were designed based on magnesium oxide replacement (from MgO–Al₂O₃–SiO₂ glass–ceramic system) with zinc oxide. Glass–ceramics were characterized by DTA, X-ray diffraction and scanning electron microscopy. Heat treatment at 1100 °C cause form gahnite crystals in glass–ceramic. Microhardness increased with increasing gahnite crystals. To achieve good mechanical properties, the initially formed high gahnite phase must transform.     

Tantalum Electrodes Modified With Well-Aligned Carbon Nanotube–Au Nanoparticles: Application to the Highly Sensitive Electrochemical Determination of Cefazolin

Carbon nanotube/nanoparticle hybrid materials have been proven to exhibit high electrocatalytic activity suggesting broad potential applications in the field of electroanalysis. For the first time, modification of Ta electrode with aligned multi-walled carbon nanotubes/Au nanoparticles introduced for the sensitive determination of the antibiotic drug, cefazolin (CFZ). The electrochemical response characteristics of the modified electrode toward CFZ were investigated by means of cyclic and linear sweep voltammetry. The modified electrode showed an efficient catalytic activity for the reduction of CFZ, leading to a remarkable decrease in reduction overpotential and a significant increase of peak current. Under optimum conditions, the highly sensitive modified electrode showed a wide linear range from 50 pM to 50 μM with a sufficiently low detection limit of 1?±?0.01 pM (S/N?=?3). The results indicated that the prepared electrode presents suitable characteristics in terms of sensitivity (458.2?±?2.6 μAcm^?2/μM), accuracy, repeatability (RSD of 1.8 %), reproducibility (RSD of 2.9 %), stability (14 days), and good catalytic activity in physiological conditions. The method was successfully applied for accurate determination of trace amounts of CFZ in pharmaceutical and clinical preparations without the necessity for samples pretreatment or any time-consuming extraction or evaporation steps prior to the analysis.     

Effect of Fe2O3 as an accelerator on the reaction mechanism of Al–TiO2 nanothermite system

Thermite reactions between aluminum and metal oxides could lead to the formation of intermetallic matrix composites used in high-temperature industrial applications. Thermite reaction in Al–TiO₂ system needs a considerable amount of energy to take place by mechanochemical or by the combustion synthesis (CS) method due to the low amount of reaction enthalpy in Al–TiO₂ system. In this study, Fe₂O₃ was chosen as a accelerator for this system, to generate a high amount of heat which could be released between Fe₂O₃ and Al, leading to a more convenient reaction between Al and TiO₂ in the CS process. The results of XRD, SEM, and DSC analyses indicated that both the mechanical activation of Al–TiO₂ system in a high-energy ball mill and the Fe₂O₃ addition led to considerable effects of reduction in the reaction temperature and increase in the reaction intensity in Al–TiO₂ nanothermite system. Finally, it was shown that Fe₃Al intermetallic compounds as well as γ-AlTi and alumina phases in the final products were formed after the CS of the milled powders.     

Comparative Study on the Effect of NaBr on the Interaction Between Alkyltrimethylammonium Bromide and β-Cyclodextrin

The effect of NaBr on the interaction between alkyltrimethylammonium bromide (CnTAB (n = 14 for TTAB and 16 for CTAB)) and ß-CD was studied by surface tension method. The first decrease in the γ_cmc of TTAB/ß-CD in the presence of NaBr mainly due to the elongated effective chain length of the hydrophobic part of the TTAB/ß-CD complexes; while the increase in the γ_cmc of both of the TTAB/ß-CD and CTAB/ß-CD in the presence of NaBr could be attributed to the close pack of CnTAB at the air/water interface.