Z. Osman

FTIR studies of chitosan acetate based polymer electrolytes

Chitosan is the product when partially deacetylated chitin dissolves in dilute acetic acid. As such, depending on the degree of deacetylation, the carbonyl, C=O-NHR band can be observed at similar to1670 cm(-1) and the amine, NH2 band at 1590 cm(-1). When lithium triflate is added to chitosan to form a film of chitosan acetate-salt complex, the bands assigned to chitosan in the complex and the spectrum as a whole shift to lower wavenumbers. The carbonyl. band is observed to shift to as low as 1645 cm and the amine band to as low as 1560 cm(-1). These indicate chitosan-salt interactions. Also present are the bands due to lithium triflate i.e. similar to761, 1033, 1182 and 1263 cm(-1). When chitosan and ethylene carbonate (EC) are dissolved in acetic acid to form a film of plasticized chitosan acetate, the bands in the infrared spectrum of the films do not show any significant shift indicating that EC does not interact with chitosan. EC-LiCF3SO3 interactions are indicated by the shifting of the C=O bending band from 718 cm(-1) in the spectrum of EC to 725 cm(-1) in the EC-salt spectrum. The Li+-EC is also evident in the ring breathing region at 893 cm(-1) in the pure EC spectrum. This band has shifted to 898 cm(-1) in the EC-salt spectrum. C=O stretching in the doublet observed at 1774 and 1803 cm(-1) in the spectrum of pure EC has shifted to 1777 and 1808 cm(-1) in the EC-salt spectrum

Conductivity enhancement due to ion dissociation in plasticized chitosan based polymer electrolytes

Abstract Cast films of chitosan acetate, plasticized chitosan acetate, chitosan acetate containing salt and plasticized chitosan acetate–salt complexes were used to obtain some insight on the mechanism of ionic conductivity in chitosan-based polymer electrolytes. The films are largely amorphous. The conductivity is due to the mobile ions from the salt. The role of the plasticizer is to dissociate the salt thereby increasing the number of mobile ions, which lead to conductivity enhancement. The conductivity was calculated using the bulk impedance obtained through impedance spectroscopy. The Cole–Cole plots illustrating the variation of the negative imaginary impedance with the real impedance do not always show the double layer reactance but the plot of dielectric constant ϵ r versus frequency tends to a maximum at low frequencies. The real and imaginary parts of the electrical modulus of samples containing salt show a “long tail” feature, which is not found in the electrical modulus spectra of the unsalted samples. This long tail feature can be attributed to high capacitance, which further supports the plasticizers role as an agent to dissociate the salt into ions.

Infrared and Conductivity Studies on Blends of PMMA/PEO Based Polymer Electrolytes

AbstractPoly(methylmetacrylate)/poly(ethylene oxide) (PMMA/PEO) based polymer electrolytes were synthesized using the solution cast technique. Four systems of PMMA/PEO blends based polymer electrolytes films were investigated:(1)PMMA/PEO system,(2)PMMA/PEO + ethylene carbonate (EC) system,(3)PMMA/PEO + lithium hexafluorophosphate (LiPF6) system and(4)PMMA/PEO + EC + LiPF6 system. The polymer electrolytes films were characterized by Impedance Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The FTIR spectra show the complexation occurring between the polymers, plasticizer and lithium salt. The FTIR results give further insight in the conductivity enhancement of PMMA/PEO blends based polymer electrolytes.

Chitosan-based electrolyte for secondary lithium cells

The system chitosan : ethylene carbonate : LiCF3SO3 was prepared by the solution cast technique. To verify that the conductivity of the material is due to the salt, the electrical conductivity at room temperature of the chitosan acetate film and that of the chitosan acetate films containing different amounts of ethylene carbonate added to it were measured. The order of magnitude of the electrical conductivity was 10−10 S cm−1. Films containing fixed content of chitosan and plasticizer but different amounts of salt were then prepared in the same manner and the highest electrical conductivity obtained was 1.3 × 10−5 S cm−1 at room temperature. These results indicate that the conductivity is due to the salt. Conductivity-temperature studies show that the ln σ T versus 103/T graphs obey Arrhenius rule implying that the conductivity occurs by way of some thermally assisted mechanism. Polarization current measurement shows that the lithium ion transference number is ∼0.09. A LiMn2O4/chitosan-LiCF3SO3/C cell was fabricated which cycled between 1.5 to 2.5 V with fading capacity. This could be the result of LiF formation due to interaction between the salt and the fluorine in the binding agent.

Studies on the properties of silicone resin blend materials for corrosion protection

Purpose – Corrosion protection is one of the important performance properties of organic coatings. The purpose of this paper is to develop a paint system for the protection of steel substrates from corrosion at high temperature atmospheres using silicone resin blend materials.Design/methodology/approach – An anti‐corrosion paint system for high temperature atmosphere has been developed using silicone polyester resins. Silicone resin has been chosen due to its good resistance for corrosion in all kinds of environments. The paint system was prepared from the best performing binder system with the addition of inorganic pigments. Heat stability was studied according to ASTM D2485 standards. Adhesion, impact resistance, film formation, thermal stability and electrochemical properties of the prepared coatings were evaluated by cross hatch adhesion method, tubular impact testing, scanning electron microscopy, differential scanning calorimetry (DSC), and electrochemical impedance spectroscopy (ELS), respectively....

Thermal and Conductivity Studies of Chitosan Acetate-Based Polymer Electrolytes

Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) have been employed to study the thermal stability of the chitosan acetate-based polymer electrolyte films. The glass transition temperature, Tg measurements confirm the conductivity enhancement effect by adding the plasticizer and salt in the chitosan acetate films

Structural and corrosion protection analyses of coatings containing silicone‐polyester resins

Purpose – Silicone and polyester resins have been prepared at various compositions with the purpose of determining the best performing binder system. The coating materials that have been developed have been analysed and evaluated for their protection ability.Design/methodology/approach – Silicone and polyester resins have been prepared at various compositions to identify best performing binder system. To evaluate the properties, different analytical methods have been employed. Fourier transform infrared spectroscopy has been utilised to study the chemical changes when the polymers were mixed together. Corrosion resistance has been tested through potential time measurement test using NaCl solution. The surface morphology has been evaluated using scanning electron microscopy/energy dispersive X‐ray (EDX) analysis.Findings – There is a change in intensity of the peaks and shift in the peak values of the functional groups observed. Scanning electron microscopy graphs show the uniform surface morphology of the...

The effect of carbonate-phthalate plasticizers on structural, morphological and electrical properties of polyacrylonitrile-based solid polymer electrolytes

Polyacrylonitrile (PAN) based solid polymer electrolyte consisting lithium tetrafluoroborate (LiBF4), ethylene carbonate (EC) and dimethyl phthalate (DMP) have been prepared using solution casting method. Comparative studies were done on unplasticized PAN-LiBF4 system and the PAN plasticized system with the novel binary plasticizers of EC and DMP in the ratio of 1:1 by the variation of LiBF4 concentration. The highest room temperature conductivity of electrolyte in PAN-LiBF4 system is 1.83 × 10−3 S cm−1 while 1.08 × 10−2 S cm−1 is obtained from PAN-EC-DMP-LiBF4 system. The complexation and structure of polymer electrolytes have been investigated as function of LiBF4 content at different weight percentages. The morphology and crystalline phase of polymer host is completely changed on the addition of salt and plasticizers. The fraction of free ions is greatly dependent on the amount of salt and the presence of plasticizers.

Studies on Sodium Ion Conducting Gel Polymer Electrolytes

Sodium ion conducting gel polymer electrolyte (GPE) films consisting of polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP) as a polymer host were prepared using the solution casting technique. Sodium trifluoromethane-sulfonate (NaCF3SO3) was used as an ionic salt and the mixture of ethylene carbonate (EC) and propylene carbonate (PC) as the solvent plasticizer. The GPE films were found to be stable up to temperature of 145 °C as shown by TGA analysis. The AC impedance study show that the optimum conductivity of 2.50 x 10-3 S cm-1 at room temperature is achieved for the film containing 20 wt.% of NaCF3SO3 salt. The temperature dependence of conductivity obeys VTF relation in the temperature range of 303 K to 373 K.

Conductivity Studies of Plasticized‐poly(methylmethacrylate) (PMMA) Polymer Electrolytes Films

In the present study, five systems of samples have been prepared by the solution casting technique. Polymethylmethacrylate (PMMA) is used as a based polymer. Ethylene carbonate (EC) and propylene carbonate (PC) as plasticizers. The salt that was selected for this study is lithium triflate (LiCF3SO3). The pure PMMA sample is taken as a reference. The five systems are the (PMMA–EC) system, the (PMMA–PC) system, the (PMMA‐LiCF3SO3) system, the ([PMMA‐EC]‐LiCF3SO3) system and the ([PMMA–PC]‐LiCF3SO3) system. The conductivity for each system is characterized using impedance spectroscopy. The conductivity of the pure PMMA, the (PMMA–EC) system and the (PMMA–PC) system at room temperature is 2.37×10−9 Scm−1, 3.63×10−8 Scm−1 and 4.18×10−8 Scm−1 respectively. On addition of salt in the (PMMA–LiCF3SO3) system, the conductivity is increased by two orders of magnitude. The conductivity for the ([PMMA–EC]‐LiCF3SO3) system and the ([PMMA–PC]‐LiCF3SO3) system is 3.54×10−5 Scm−1 and 2.06×10−5 Scm−1 respectively. The cond...