Ahmad Kabbani

Ambient solid-state mechano-chemical reactions between functionalized carbon nanotubes

Carbon nanotubes can be chemically modified by attaching various functionalities to their surfaces, although harsh chemical treatments can lead to their break-up into graphene nanostructures. On the other hand, direct coupling between functionalities bound on individual nanotubes could lead to, as yet unexplored, spontaneous chemical reactions. Here we report an ambient mechano-chemical reaction between two varieties of nanotubes, carrying predominantly carboxyl and hydroxyl functionalities, respectively, facilitated by simple mechanical grinding of the reactants. The purely solid-state reaction between the chemically differentiated nanotube species produces condensation products and unzipping of nanotubes due to local energy release, as confirmed by spectroscopic measurements, thermal analysis and molecular dynamic simulations.

Adsorptive kinetic mechanism of heavy metal cations on the surface of graphite oxide and its SiO2 composite

Nanomaterials have gained great attention because of their novel size- and shape-dependent properties, large specific surface area and high reaction activity. Moreover, nanomaterials have a wide range of applications, as in the technological and environmental challenges in the areas of solar energy conversion, catalysis, medicine, and water treatments. In the present study, nanostructured graphite oxide, silica/graphite oxide composites and silica nanoparticles were used for the removal of the heavy metal ions from aqueous solutions by a batch adsorption method and the adsorptive kinetic mechanism of heavy metal cations on the surface of graphite oxide and its SiO2 composite was evaluated. The experimental results revealed a strong adsorption of the metal cations on the surface of graphite oxide, this is reflected in the shifts in wave numbers after adsorption with nanostructured graphite oxide and the big shift in wave numbers (Δv) for nickel ions reflects chemosorption type of adsorption. This is confi...

XPS yield calculation for solid-state reactions of CNTs unzipping leading to graphene

T widespread usage of corrugated steel plates as girders and steel shear walls necessitates the need for further investigation of these efficient structural members. Having significant initial stiffness, high capability of energy dissipation and special geometry are the fundamental reasons for this study. The nonlinear behaviour of trapezoidal corrugated steel shear walls with rectangular opening has been studied in this paper. A series of corrugated and simple shear walls with and without opening regarding different angles of corrugation and different infill plat thicknesses have been investigated. This analytical study was conducted to compare the initial stiffness, ultimate strength, energy dissipation and force-displacement curves of corrugated steel shear walls. Additionally, the results show that utilizing trapezoidal corrugated panels increase initial stiffness, capability of energy dissipation and ductility, while reducing the ultimate strength of shear wall system with opening. In addition, corrugated steel shear wall postpones the ultimate strength and degradation point compared with corresponding unstiffened steel shear wall, which is highly beneficent seismic characteristic of these structural elements. Furthermore, the corrugated steel shear wall’s appropriate opening position is determined according to ultimate strength, initial stiffness and ductility of the models.In the present study soft ferrimagnetic glass ceramic nanoparticles (MNPs) were prepared by high energy mechanical ball milling utilizing a planetary ball mill. Various MNPs samples were produced by changing the milling time from 1h to 5h, in the constant milling speed of 1200 rpm. Transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) analysis were performed to determine the characteristics of primary (unmilled) and milled samples. Using high energy planetary ball milling technique, nanoparticles with a very narrow particle size distribution and uniform spherical shaped morphology were obtained. The average particle size reached after 5 hours milling was 10 nm. Moreover, it was found that the saturation magnetization decreased with increasing milling time. The coercivity decreased and after that increased to reach 88 Oe after 5 hours milling.Polyurethanes (PUs) were prepared by cross-linking β-cyclodextrin (β-CD) with two different types of diisocyanates, respectively. Materials with diverse structural and textural properties were obtained by varying the rate of diisocyanate addition: rapid (R) or drop-wise (D; 0.1 mL/min). Characterization of the structural and textural properties was investigated by spectroscopic (H NMR in solution, solid state C CP-MAS solids NMR, dynamic light scattering, UV-vis, and IR), thermogravimetric analysis, powder x-ray diffraction, and scanning electron microscopy. The accessibility of the β-CD inclusion sites of the polymers was independently evaluated using an equilibrium dye adsorption method at equilibrium and in parallel with a kinetic dye-based uptake method. The characterization methods strong support that drop-wise additions affords materials with greater cross-linking relative to the rapid addition method. Herein, we report the first example of a cross-linked polyurethane containing β-CD with tunable structure and physicochemical properties, according to the mode of cross-linker addition (R versus D) to control the reaction conditions.I the design of electronic devices a compromise must be done between conductivity and optical transparency because increasing thickness will increase conductivity,but decreases the transparency. Graphene or single-layered graphite is a twodimensional nanomaterial that has its sp2 carbon arranged in a honeycomb hexagonal lattice. Its unique properties such as high carrier mobility (2x105 cm2 V-1s-1),high Young modulus, (~1100GPa), excellent thermal conductivity, (~ 5000Wm -1K-1), high specific surface area,(~ 2630 m2/g), makes it an excellent candidate for many applications such as the assembly of high-performance electronics, reinforced composites, catalysis, energy conversion , storage devices, and in environmental remediation. We have recently explored the solid-state reaction of multiple-walled carbon nanotubes(CNTs) decorated by OH and COOH and established the solid-state hydrogen –bond mediated proton transfer mechanism of the CNTs unzipping.. In the present work ,we expand on this type of solid-state reactions using X-ray photoelectron spectroscopy [XPS] for calculation of yield of reaction and Raman spectroscopy for quality of the graphene product.Also,the 60% graphene reaction with residual of unreacted CNT is discussed for the possible fabrication of hydrogels.I is well-known that Pb(Zr, Ti)O3 (PZT) based piezoelectric ceramics play a dominant role in current piezoelectric applications such as transducers, actuators, and sensors, owing to their excellent electrical properties and very good temperature stability. Some piezoelectric devices including lead compounds may be prohibited in the near future. Therefore, it is urgent to develop lead-free piezoelectric materials substituting for the widely used PZT system. The main aim of our research is fabricate lead free nanoceramic materials by high energy ball milling method and can be used in practical applications especially piezoelectric sensors. Lead free Piezoelectric ceramics (Ba1−xCax) (TiO.94Sn0.1)O3 (BCST ) (x =0.0, 0.02, 0.04, 0.06, 0.08 and 0.1) ceramics have been prepared by solid state reaction mixture technique with calcined temperature 1200oC and sintering temperature 1400oC for 4 hours. The effects of Ca content on the phase structure and electrical properties of the BCST ceramics were studied. At room temperature, a polymorphic phase transition (PPT) from orthorhombic phase to tetragonal phase was identified from XRD patterns in the composition range of 0.02 < x < 0.04 and all compositions have a single phase which confirmed by XRD. The microstructure was investigated by (SEM) and (EDAX). The sintering curve was achieved by hot microscope to optimize the sintering temperature. Dielectric constant and electrical properties (er) measured by (LCR) meter with various temperatures at constant frequency [10, 100 KHz and 1 MHz]. The humidity properties – change the resistance with the relative humidity (RH) for all composition researched, where there is no change for resistance with change of relative humidity which means that these compositions are stable and linearity in the range of 33–90 % (RH) at high relative humidity.

Synthesis and characterization of covalently bound benzocaine graphite oxide derivative

Graphite oxide (GO) derived materials include chemically functionalize or reduced graphene oxide (exfoliated from GO) sheets, assembled paper-like forms , and graphene-based composites GO consists of intact graphitic regions interspersed with sp3-hybridized carbons containing hydroxyl and epoxide functional groups on the top and bottom surfaces of each sheet and sp2-hybridized carbons containing carboxyl and carbonyl groups mostly at the sheet edges. Hence, GO is hydrophilic and readily disperses in water to form stable colloidal suspensions Due to the attached oxygen functional groups, GO was used to prepare different derivatives which result in some physical and chemical properties that are dramatically different from their bulk counterparts .The present work discusses the covalent cross linking of graphite oxide to benzocaine or ethyl ester of para-aminobenzoic acid,structure I,used in many over-the-counter ointment drug.Synthesis is done via diazotization of the amino group.The product is characterized via IR,Raman, X-ray photoelectron spectroscopy as well as electron microscopy.