The effects of Ni-addition on the crystal structure,thermal properties and morphology of Mg-based hydroxyapatites synthesized by a wet chemical method

Four Mg-based hydroxyapatites (HAps) doped with Ni at various amounts of 0, 0.6, 1.2 and 1.8?at% were prepared at the temperature of 870?°C by a wet chemical synthesis. The crystallite size, lattice parameters and crystallinity percent dramatically decreased with adding of Ni. The amount of HAp phase for all the Ni-containing samples is smaller than that of the Ni-free MgHAp. Furthermore, the lattice strain, stress and anisotropic energy density values were affected by the amount of Ni. The differential thermal analysis (DTA) measurements taken in the temperature range from 25 to 1000?°C showed that all the samples are thermally stable. No significant change in the morphology was observed. It was observed that the gradual introduction of Ni caused the Ca-deficiency.     

Synthesis and characterization of triptycene type cross-linker and its use in photoinduced curing applications

A novel triptycene type diacrylate cross-linker, triptycene hydroquinone diacrylate (THDA) was synthesized from the reaction of triptycene hydroquinone with acryloyl chloride and characterized. The photocuring behaviour and the reaction kinetics of the synthesized cross-linker were investigated by means of photo-differential scanning calorimetry (photo-DSC) experiments. Formulations containing monofunctional (meth)acrylate monomers, namely glycidyl methacrylate (GMA), 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), and 2-ethylhexyl methacrylate (EHMA), cross-linker, THDA and 2,2-dimethoxy-2-phenylacetophenone (DMPA) as a photoinitiator were irradiated. A conventional cross-linker without triptycene unit such as hydroquinone diacrylate (HDA) was used under the same conditions for comparison. The effects of the structure of the monofunctional monomer and triptycene moiety on the photopolymerization kinetics were evaluated and discussed.     

Structural and Dielectrical Properties of Ag- and Ba-Substituted Hydroxyapatites

Ag- and Ba-doped hydroxyapatite (HAp) samples were synthesized by sol–gel method. The crystallite sizes for all the samples were found to vary from 26 to 39 nm. Neither Ag nor Ba did result in dramatic changes in the morphology of all the samples, and the Ca/P molar ratio was varied. The dielectric parameters of the samples were changed with the dopant content. The maximum and minimum values of the dielectric constant were observed for 2.0 %Ba-HAp and 0.5 %Ba-HAp samples. The alternating current conductivity indicates that all the samples exhibit the insulator behavior. The results of the biological tests revealed that Ag-containing samples have an antimicrobial activity, while no antimicrobial activity was detected for both HAp and Ba-doped HAp samples.     

Synthesis of 9H-carbazole-9-carbothioic methacrylic thioanhydride,electropolymerization, characterization and supercapacitor applications

A novel organic molecule of 9H-carbazole-9-carbothioic methacrylic thioanhydride (CzCS₂metac) was synthesized by incorporating CS₂ and methacrylate groups into the carbazole monomer structure. CzCS₂metac was characterized by FTIR, ¹H-NMR and ¹³C-NMR spectroscopy. CzCS₂metac was electropolymerized in 0.1 M tetraethylammonium tetrafluoroborate (TEABF₄)/acetonitrile (CH₃CN) on glassy carbon electrode (GCE). The characterization of the electrocoated P(CzCS₂metac)/CFME thin film was studied by various techniques, such as cyclic voltammetry, scanning electron microscopy–energy-dispersive X-ray analysis and electrochemical impedance spectroscopy. The specific capacitance (C _sp) of P(CzCS₂metac)/MWCNT/GCE in the scan rate of 20 mV s^?1 (C _sp = 38.48 F g^?1 from area formula, C _sp = 38.52 F g^?1 from charge formula) was increased ~15.66 and ~15.64 times in area and charge formulas compared to P(CzCS₂metac)/GCE (C _sp = 2.46 F g^?1 from area and charge formulas). The same results were also obtained from Nyquist graphs. The specific capacitance value of composite film (C _sp = 1.09 × 10^?3 F) is ~15.66 times higher than the polymer film (C _sp = 6.92 × 10^?5 F). The composite film may be used as supercapacitor electrode material in energy storage devices.     

Electrochemical Polymerization of Thiophene and Poly(3-hexyl)thiophene,Nanocomposites with TiO2, and Corrosion Protection Behaviors

Thiophene, 3-hexylthiophene, and their nanocomposites with TiO₂ were electropolymerized on Al1050 electrode by chronoamperometric technique. Different concentrations of thiophene and 3-hexylthiophene homopolymers and their nanocomposites with TiO₂ (2% in total content) were characterized by attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersion X-ray analysis, and electrochemical impedance spectroscopy. The anticorrosion tests for homopolymers and nanocomposite films were examined on Al1050 in 3.5% NaCl solution. Poly(3-hexylthiophene)/TiO₂ nanocomposite films gave the highest protection efficiency of 98% because the amount of defects was much lower than that for the poly(3-hexylthiophene), polythiophene, and polythiophene/TiO₂ films.     

Characteristics of Fe-exchanged natural zeolites for the decomposition of N2O and its selective catalytic reduction with NH3

Natural zeolites obtained from various regions of Turkey and their iron-exchanged forms were characterised by XRD, BET, H₂-TPR and NH₃-TPD methods. Transient experiments with N₂O showed that the iron introduced into natural zeolites have appreciable oxygen deposition capacity due to isolated iron species involved. Atomic surface oxygen species in these zeolites are formed at 250 °C, which is released through increasing the temperature until 900 °C, similar to Fe-containing ZSM-5 zeolite. The steady-state experiments indicate that the iron-containing zeolite of the Yavu-Sivas region, in particular, has high activity in selective catalytic reduction of N₂O with NH₃ as a consequence of isolated cationic and/or dimeric iron content.     

Synthesis, characterization and thermally activated curing of polysulfones with benzoxazine end groups

Polysulfones with benzoxazine end groups (PSU-B-a) were obtained using monomer synthesis method from the phenol terminated polysulfone (PSU-OH), aniline and paraformaldehyde as starting materials. For this purpose, the precursor PSU-OHs with different molecular weights were prepared by condensation of bisphenol-A and bis(p-chlorophenyl) sulfone in presence of potassium carbonate. The structure of the polymers before and after functionalization was confirmed by proton nuclear magnetic resonance spectroscopy (¹H NMR) and Fourier transform infrared spectroscopy (FT-IR). Thermally activated crosslinking behavior of these polymers was investigated by differential scanning calorimetry (DSC). Thermal and tensile properties of the crosslinked polymers obtained from PSU-B-a alone or with low molar mass benzoxazine (P-a) were studied by thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA).     

Poly(3-Octylthiophene) and Poly(3-Octylthiophene)/TiO2-Coated on Al1050: Electrosynthesis,Characterization and Its Corrosion Protection Ability in NaCl Solution

In this study, 3-octylthiophene (3OT) and its nanocomposites with TiO₂(3OT/TiO₂) were electrochemically synthesized in different initial monomer concentrations (50, 75, 100, and 150 mM) in 0.1 M tetraethylammonium tetrafluoroborate (TEABF₄)/acetonitrile (CH₃CN) on a glassy carbon electrode (GCE). The best modified electrodes, which were taken from the optimum conditions of redox behaviors, were also electropolymerized in 0.5 M oxalic acid/acetonitrile (CH₃CN) solution on Al1050 electrode. The modified Al1050 electrodes were characterized by optical microscope, FTIR-ATR, SEM-EDX, and EIS. The optimum conditions of the electrocoated P(3OT)/Al1050 and P(3OT)/TiO₂ nanocomposites on Al1050 electrode were investigated for corrosion performances against 3.5% NaCl solution. The corrosion tests were performed by EIS and Tafel extrapolation plots together with the equivalent circuit model of R_s(Q_c(R_c(Q_pR_ct))). P(3OT)/TiO₂ nanocomposite films showed higher protection efficiency (PE = 89%) than P(3OT) films (PE = 81%). The P(3OT)/TiO₂ nanocomposite films coated on Al1050 electrodes may be used in industrial applications of corrosion protection against salt water.     

Carbon nanotube-based nanocomposites and their applications

The purpose of the current review article is to present a compherensive understanding regarding pros and cons of carbon nanotube–related nanocomposites and to find ways in order to improve the performance of nanocomposites with new designs. Nanomaterials including carbon nanotubes (CNTs) are employed in industrial applications such as supercapacitors, and biosensors, and etc. The present article has been prepared in three main categories. In the first part, carbon nanotube types have been presented, as single-walled carbon nanotubes, multi-walled carbon nanotubes, and also equivalent circuit models, which have been used to more clarify the experimental measurements of impedance. In the second part, nanocomposites with many carbon, inorganic and polymeric materials such as polymer/CNT, activated carbon/CNT, metal oxide/CNT, and carbon fiber/CNT have been investigated in more detail. In the third part, the focus in on the industrial applications of CNTs. including supercapacitors, biosensors, radar absorbing materials, solar cells, and corrosion protection studies. This review article explains the latest advances in carbon nanotubes and their applications in electrochemical, electrical and optical properties of nanocomposites.