Zuhal Küçükyavuz

Voltammetric determination of imipramine hydrochloride and amitriptyline hydrochloride using a polymer-modified carbon paste electrode.

In this paper the voltammetric behaviors of imipramine.HCl and amitriptyline. HCl, which are both tricyclic antidepressants, were investigated using a carbon paste electrode, modified by the addition of poly(N-vinylimidazole), in various solutions of different pHs. It was shown that the current density for imipramine increased with modification of the carbon paste electrode and amitriptyline, which was electroinactive with the normal carbon paste electrode, became electroactive on the modified electrode. The optimum conditions for the quantitive determination of imipramine.HCl and amitriptyline.HCl were determined and statistical analysis of the linear relationship between current and concentration is given. The method was applied for the determination of these substances in the pharmaceutical dosage forms.

Synthesis, characterization and electrical properties of iodinated poly(N-vinylimidazole)

Abstract Poly( N -vinylimidazole) was synthesized by radical polymerization. The synthesis of this conducting polymer was achieved via iodination before doping. Characterization of the product was based on elemental analysis, FT-IR spectral analysis and differential scanning calorimetry (DSC) techniques. The long-lasting conductivity of iodinated poly( N -vinylimidazole) leads us to propose that a more stable charge transfer complex was formed between the dopant and polymer. The changes in conductivity of iodinated poly( N -vinylimidazole) with time and the temperature dependence of its electrical conductivity were also studied.

Monomer reactivity ratios of styrene-4-vinylpyridine copolymers at low and high conversions

Abstract Monomer reactivity ratios in free-radical copolymerization of styrene and 4-vinylpyridine monomers at 80°C in toluene solution under reduced pressure were determined for low and high conversions. Finemann-Ross, Kelen-Tudos, extended Kelen-Tudos and Mayo-Lewis methods were used for this purpose. The most reliable method was found to be the extended Kelen-Tudos method. By the use of this method, for conversions below 20%, monomer reactivity values of 0.700±0.005 and 0.335±0.001 were calculated for 4-vinylpyridine and styrene respectively. For conversions greater than 20%, these values were found to reduce to 0.538±0.004 and 0.277±0.001 respectively.

Conductive properties of poly(4-vinylpyridine)-poly(dimethylsiloxane) block copolymers doped with tetracyanoquinodimethane

Abstract Poly(4-vinylpyridine)-poly(dimethylsiloxane) (P4VP-PDMS) block copolymers with various compositions were prepared by anionic polymerization. The 4VP block was quaternized with methyl iodide and reacted with 7,7′,8,8′-tetracyanoquinodimethane (TCNQ), which is in both anion radical (TCNQ − ) and neutral form (TCNQ 0 ). The products were then characterized by 1 H nuclear magnetic resonance and Fourier-transform infra-red spectroscopy, scanning electron microscopy and differential scanning calorimetry techniques. The electrical conductivities of processable and flexible films of these block copolymers were measured with the four-probe method and found to be as high as 10 −2 S cm −1 . The optimal TCNQ 0 doping for which the conductivities are highest were also determined.

Synthesis and Characterization of Surface Modified Fullerene

Fullerenes were chemically functionalized by using sulphuric acid and nitric acid. The functionalization was done with two different acid ratio. The functionalized nanotubes were characterized with Fourier transform infrared spectroscopy and X-ray photonelectron spectroscopy (XPS), elemental analysis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Sulfonation of fullerene increased the electrical conductivity of fullerenes up to 0.027 S/cm. TEM micrographs showed that sulfonation improves the dispersion of fullerene in water. Zeta potential measurements also proved this result.

Solution properties and unperturbed dimensions of poly(p-tert-butylstyrene)

Abstract The conformational and thermodynamic properties of poly( p -tert-butylstyrene) were investigated by osmometry, intrinsic viscosity, light scattering, gel permeation chromatography and phase equilibria measurements. Polymeric samples were anionically synthesized. 1-Nitropropane was found to be a θ-solvent for this polymer and the θ-temperature was determined as 31°C. Intrinsic viscosity-molecular weight relationships were obtained in a few solvents. Unperturbed dimensions, estimated from both viscosity and light scattering results, led to the characteristic ratio, C α , of 13.4 ± 0.7 at 31°C. Comparison of this value with those for other polystyrene derivatives shows that the characteristic ratio increases with the bulkiness of the side-group due to the steric effect.

Synthesis and characterization of conducting polypyrrole-cis-1, 4-polybutadiene composites

Abstract Conducting composite films of cis -1,4-polybutadiene with polypyrrole were prepared electrochemically. Polymerization of pyrrole was carried on cis -1,4-polybutadiene-coated platinum electrodes. The composites having different polypyrrole percentages showed conductivity in the range 10 −1 −10 −6 S/cm. Conductivity measurements were done by using the standard four-probe technique. Characterization of the samples was carried out by FT-IR, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) techniques. Temperature dependence of electrical conductivity was also studied.

Surface Modification and Characterization of Multi-Walled Carbon Nanotube

Multi-walled carbon nanotubes (MWCNTs) were chemically functionalized by using sulfuric acid and nitric acid. The functionalization was done with two different acid ratio. The functionalized nanotubes were characterized with Fourier Transform Infrared Spectroscopy, X-Ray Photon Spectroscopy, Thermal Gravimetric Analysis, Elemental Analysis, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy. Sulfonation of carbon nanotubes (CN) increased the electrical conductivity of carbon nanotubes up to 1.25 × 10−1 S/cm. The SEM micrographs of the samples showed that CN was observed in more bulky form due to the increasing hyrogen bonding between the particles. The zeta potential of the CN increased with increasing sulfonation amount.

Electrically conductive polymers from poly(N-vinylimidazole)

Abstract Poly(N-vinylimidazole) was synthesized by free radical polymerization. It was quaternized with methyl iodide. The samples were doped with iodine and borontrifluoride. Products were characterized by elemental analysis. Fourier transform infra-red spectroscopy and differential scanning calorimetry techniques. The maximum electrical conductivities achieved were 10−4 S cm−1 for BF3-doped and for I2-doped QPVI. The decrease of electrical conductivity in open atmosphere with time was also studied to understand the stability of doped polymers. Temperature dependence of electrical conductivity exhibits a semiconductor behaviour.

Electrical and Mechanical Properties of Polypropylene/Carbon Black Composites

Polypropylene(PP)/carbon black(CB) composites at different compositions were prepared via melt blending of PP with CB. The effect of CB content on mechanical and electrical properties was studied. Test samples were prepared by injection molding and compression molding techniques. The effect of processing type on mechanical and electrical properties was also investigated. Composites become semi-conductive by addition of 2 wt% CB. The relation between mechanical and electrical properties was discussed. The influence of CB content on morphology and crystallinity was also studied.