Effect of NaI doping on same physical characteristic of (PVA)0.9-(KHSO4)0.1 composite films

Electrolyte composite films of Polyvinyl alcohol (PVA)0.9 filled with potassium hydrogen sulfate (KHSO4)0.1 with different concentration of sodium iodide (NaI) were prepared using solution caste technique. The absorption spectral analysis data were carred for the samples to determine the influence of NaI contents, the obtained data showed that the direct allowed optical energy gap of the films decreases from  to  with increasing NaI contents up to  weight. Furthermore, in order to understand the behavior of electrical conduction in these composite, the alternating electrical conductivity and dielectric permittivity have been investigated for different concentration of NaI at temperature range  over the frequency ranging from  to . The electrical conductivity of the composite increased with increasing temperature and it obeys power law  in which s is in the range of . Keywords: Electrolyte composite, Optical constants, Dielectric constant, Energy gap, Electrical conductivity

Modified Hartree-Fock Relationship to Calculate the Effective Energy of Atomic Sub-shells in Transition Elements

In this study, the part in question of the total energy is that due to the mutual interactions between the electrons themselves, the fact that this is the total effective energy of sample electrons in shells and sub-shells. The result was that only 0.2564 of the total energy of the atom is divided between the individual electrons and the effective energy of each of them is proportional to the reciprocal of their occupation numbers i.e. 1/(n+2l+1)2, the proportionality constant was fortunately equivalent to the effective nuclear charge (Zeff) of the sub-shell type according to the studies done by both Slater and Clementi and Raimondi. The amazing news was that the algebraic sum of the effective energy for each electron was again very close to 0.2564 ET. Keywords: Hartree-Fock, Effective Energy of Atomic, Transition Element

Optical Characterization of Polyvinyl alcohol - Ammonium Nitrate Polymer Electrolytes Films

Polyvinyl alcohol – Ammonium Nitrate polymer electrolyte films were prepared by casting method. UV-Vis Double Beam Spectrophotometer in the wavelength range (190-1100) nm were used to investigate the optical properties. The optical constants such us, transmission spectra, refractive index, extinction coefficient, real and imaginary parts of the dielectric constant, optical band gaps, and optical conductance are found. It was found that the energy band gaps are decreased upon the increase of salts concentration. The values of the width of the tails of localized states in the forbidden gap of the films obtained from Urbach plots are varied from 0.64 to 1.16 eV. The real and imaginary part of dielectric constant of the polymer electrolyte films increases with increasing NH4NO3 concentration. The dielectric constant shows decreases abruptly in the wavelength (235-260) nm, and finally becomes constant with increase wavelength. Keywords: optical energy band gap; optical conductance; refractive index; extinction coefficient

Optical Properties of the Synthesized Cr2S3 Nanoparticles Embedded in Polyvinyl Alcohol

Polyvinyl alcohol (PVA) based nanocomposite, with different concentrations of chromium sulfide Cr2S3 nanoparticles, were prepared by reduction of Cr(NO3)3 and Na2S in an aqueous PVA solution, using the chemical reduction rote, and casting technique. Effect of Cr2S3 nanoparticles on optical parameters such as absorbance, absorption coefficient, refractive index, and extinction coefficient have been investigated using UV-Visible spectroscopy. The study reveals that all these parameters are affected by the Cr2S3 nanoparticles concentration. The study has been also extended to investigate the changes in the optical band gap energies, the band tail width for the samples using Tauc and Urbach relations respectively. The optical energy band gap reduced from (6.17 eV) for pure PVA to (4.14 eV) for 0.04M Cr2S3; while the Urbach tail increased from (0.216 eV) for pure PVA to (0.523 eV) for 0.04M Cr2S3. The significant change of the optical properties of PVA with embedded Cr2S3 nanoparticles suggested their applicabilit  in optical devices

Preparation and Composition Optimization of PEO:MC Polymer Blend Films to Enhance Electrical Conductivity

The polymer blend technique was used to improve amorphous phases of a semicrystalline polymer. A series of solid polymer blend films based on polyethylene oxide (PEO) and methylcellulose (MC) were prepared using the solution cast technique. X-ray diffraction (XRD), Polarized optical microscope (POM), Fourier transform infrared (FTIR) and electrical impedance spectroscopy (EIS) were used to characterize the prepared blend films. The XRD and POM studies indicated that all polymer blend films are semicrystalline in nature, and the lowest degree of crystallinity was obtained for PEO:MC polymer blend film with a weight ratio of 60:40. The FTIR spectroscopy was used to identify the chemical structure of samples and examine the interactions between chains of the two polymers. The interaction between PEO and MC is evidenced from the shift of infrared absorption bands. The DC conductivity of the films at different temperatures revealed that the highest conductivity 6.55 × 10−9 S/cm at ambient temperature was achieved for the blend sample with the lowest degree of crystallinity and reach to 26.67 × 10−6 S/cm at 373 K. The conductivity relaxation process and the charge transport through the hopping mechanism have been explained by electric modulus analysis. The imaginary part of electrical modulus M″ shows an asymmetrical peak, suggesting a temperature-dependent non-Debye relaxation for the PEO:MC polymer blend system

The impact of multi-walled carbon nanotubes on the thermal stability and tensile properties of epoxy resin hybrid nanocomposites

In this study, hybrid polymer nanocomposites were fabricated using epoxy resin (EPR) incorporated with zirconium dioxide (ZrO2) and yttrium oxide (Y2O3) nanoparticles (NPs), reinforced with multi-walled carbon nanotube (MWCNT) using hand lay-up casting technique. The mechanical, structural, and thermal stability of the hybrid nanocomposites were systematically investigated. The addition of a small amount of MWCNT is shown to improve the hybrid nanocomposites’ mechanical and thermal properties. For instance, the hybrid polymer nanocomposite containing 1 wt% NPs with the presence of 0.1 wt% of MWCNT show maximum tensile strength and Young’s modulus of 48.92 MPs and 2492.06 MPa, which increased by, respectively, 23 % and 37 % in comparison to pure EPR. Furthermore, adding nano-fillers to the hybrid composites caused a slight improvement in the glass transition temperature and thermal stability of the matrix. Consequently, the presence of the MWCNTs in the EPR nanocomposite matrix could make the product stronger as well as tougher. Overall, the improvement in mechanical properties with the stable thermal stability of the present hybrid nanocomposites indicates that it is a suitable candidate for structural and sub-structural construction

Hydrogen sulfide sensors based on PANI/f-SWCNT polymer nanocomposite thin films prepared by electrochemical polymerization

Hydrogen sulfide (H2S) gas sensors in the form of thin films based on polyaniline (PAN) incorporated with various concentrations of functionalized single wall carbon nanotubes (f-SWCNT) were prepared by electrochemical polymerization of Aniline monomer with sulfuric acid in an aqueous solution. Surface morphology of the thin film nanocomposites was investigated by Field Emission Scanning Electron Microscopy (FE-SEM) and revealed that the f-SWCNTs were almost uniformly distributed on the surface of the host PANI matrix. The X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, and Hall effect measurements were used to characterize the synthesized PANI/f-SWCNT nanocomposites. The Hall measurements reveal the p-type conductivity. The grown FTIR band at 1145 cm−1 with the increase of the f-SWCNT content evidence a formation of charge transfers due to a remarkable interaction between PANI and f-SWCNTs. The response of this nanocomposite film towards the H2S gas was investigated by monitoring the change in the electrical resistance with the time in the presence of 30% H2S at different operating temperatures. The sensing analysis showed that the sensitivity increased with f-SWCNT content in the PANI matrix. The rapid response/recovery times toward the H2S gas, at 50 °C, was achieved for a PANI/0.01% f-SWCNT nanocomposite sample. Keywords: Conductive polymer, PANI, Nanocomposites, f-SWCNT, H2S gas senso

Structural and optical characterization of PVA:KMnO4 based solid polymer electrolyte

Solid polymer electrolyte films of polyvinyl alcohol (PVA) doped with a different weight percent of potassium permanganate (KMnO4) were prepared by standard solution cast method. XRD and FTIR techniques were performed for structural study. Complex formation between the PVA polymer and KMnO4 salt was confirmed by Fourier transform infrared (FTIR) spectroscopy. The description of crystalline nature of the solid polymer electrolyte films has been confirmed by XRD analysis. The UV-Visible absorption spectra were analyzed in terms of absorption formula for non-crystalline materials. The fundamental optical parameters such as optical band gap energy, refractive index, optical conductivity, and dielectric constants have been investigated and showed a clear dependence on the KMnO4 concentration. The observed value of optical band gap energy for pure PVA is about 6.27 eV and decreases to a value 3.12 eV for the film sample formed with 4 wt% KMnO4 salt. The calculated values of refractive index and the dielectric constants of the polymer electrolyte films increase with increasing KMnO4 content. Keywords: Solid polymer electrolyte, XRD analysis, FTIR study, Optical band gap, Dielectric constant, Refractive inde

Simulation Study for the Ceramic Powder Compaction Proces

The accurate simulation of powder compaction involves many different areas in computational mechanics, where appropriate elastoplastic constitutive model, finite deformation framework, enforcement of contact, friction conditions and robust numerical methods are some of the requirements demanded in this simulation. The modified Drucker-Prager Cap (DPC) elasto-plastic constitutive model is used for the calculations that performed using the finite element code ABAQUS 6.4, to simulate densification of alumina powder using cold die pressing. A comparison of the experimental and theoretical density distribution shows that there is a good qualitative agreement in the sense that both produce the important maximum and minimum density regions accurately, despite the overall density distribution of present work is slightly underestimated experimental data