Films of polyvinyl alcohol (PVA), Methacrylic Acid - Ethyl Acrylate (MAA:EA) copolymer and their blends PVA:MAA:EA of composition 80:20, 60:40, 50:50, 40:60, 20:80 (wt %) were prepared by using the ...solution cast technique. The prepared films were investigated by structural, optical and thermal studies. X-ray diffraction (XRD) scans revealed the semicrystalline nature of the blends for lower concentrations of PVA up to 60 wt % and the amorphous nature for higher ones. Fourier transform infra-red spectroscopy (FTIR) of blend samples indicates that there is a compatibility between PVA and MAA:EA copolymers through the formation of hydrogen-bonding between their polar groups. SEM image of polymer blend suggested the presence structural reorganization of polymer chains. UV-Visible spectral analysis revealed that the intensity of the shoulder around 271 nm decreases with increasing MAA:EA content. In DSC analysis, a single glass transition temperature for each blend was observed, which supports the existence of compatibility of such systems. From the observed results, 50:50 (wt %) PVA/MAA:EA is found to be the optimum blending ratio.
Structural, optical, thermal and morphological studies were performed on pure Polyvinyl alcohol/Methacrylic Acid – Ethyl Acrylate (PVA/MAA:EA (50:50)) blend and PVA/MAA:EA blend filled with different ...concentrations (5, 10 and 15 wt%) of Lithium Perchlorate (PVA/MAA:EA: LiClO4) prepared by a solution casting method. XRD patterns demonstrated that the peak intensity at 2θ = 19.5° decreased and the bandwidth increased with increasing the concentration of LiClO4, which implied a decrease in the degree of crystallinity and hence caused an increase in the amorphous nature. UV – Visible analysis revealed that the values of both direct and indirect band gaps were decreased with increasing LiClO4 content in the polymer host. This indicated the formation of charge transfer complexes between the polymer blend and the filler. The dTGA curves show three different steps of weight loss. This is due to the loss of water adsorbed, the elimination of the side chains, and the decomposition of the main chain. For LiClO4 filled PVA/MAA:EA, FTIR spectra showed disappearance of some bands with the change in their intensities as compared to pure PVA/MAA:EA film. This indicated considerable interaction between the polymer blend and LiClO4 filler. SEM images of the polymer blend films complexed with LiClO4 suggested the presence of a structural rearrangement of the polymer chains. The electrical conductivity of the prepared films was measured using the impedance analyzer in the frequency range from 1 Hz to 5 MHz at room temperature. It was observed that the conductivity increased with increase of the Li+ion concentration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pure and VO2+ ions doped PVA/MAA:EA polymer blend films were prepared by a solution casting method. XRD pattern reveals an increase in amorphicity with increase in doping. The dTGA study shows an ...enhancement of thermal stability of the system with increase in dopant concentration. The optical absorption spectrum exhibits three bands corresponding to the transitions 2B2g→2A1g, 2B2g→2B1g and 2B2g→2Eg, characteristic of VO2+ ions in octahedral symmetry with tetragonal distortion and reflects that the optical band gap decreases with the increase of mol% of VO2+. EPR spectra of all the doped samples show a characteristic eightline hyperfine structure of VO2+ ions, which arises due to the interaction of unpaired electron with the 51V nucleus. The spin-Hamiltonian parameters (g and A) evaluated from the EPR spectra confirm that the vanadyl ions exist as VO2+ ions in octahedral co-ordination with a tetragonal compression and have a C4v symmetry. The impedance spectroscopic study shows that the addition of VO2+ ions into the polymer blend system enhances the ionic conductivity which is explained in terms of an increase in the amorphicity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A solid polymer blend electrolyte was prepared by using Polyvinyl alcohol (PVA) and Methacrylic Acid Ethyl acrylate (MAA: EA) polymers with different weight percentages (Wt%) of Potassium Chloride ...(KCl) by using solution casting technique, with water as a solvent. The structural, thermal, optical, and electrical properties of the prepared samples were studied. The X-ray diffraction pattern shows the decreasing trend in the degree of crystallinity due to the incorporation of KCl into the polymeric matrix. From the FTIR analysis, some peak intensities were decreasing and shifted in the case of KCl complexed films, which results in the complexation between the polymer blend and dopant ions. The TGA analysis reveals that the thermal stability of the KCl complexed films increases as dopant concentration increases. The SEM images reveal the structural reorganisation of polymer chains in the KCl complexed polymer blend electrolytes. UV-VIS spectra show that the optical constants such as absorption edge and band gap (both direct and indirect) values are decreased with an increase in KCl concentration. From conductivity data, it was noticed that the conductivity increased with the increase in the K
+
ion concentration. The maximum ionic conductivity of 1.85 × 10
−7
S/cm was obtained for the sample having 15 wt% of KCl salt.
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PVA/MAA:EA polyblend films doped with various concentrations of Cu
2+
(1.0, 2.0, 3.0, 4.0 and 5.0 mol%) were synthesised using solution casting method. Thermogravimetric analysis (TGA) reveals ...a decrease in thermal degradation temperature with an increase in Cu
2+
concentration, which shows an increase in the amorphicity of the polyblend. UV-Vis spectra show a decrease in band gap with an increase in Cu
2+
concentration. and bands at 675 and 390 nm corresponds to
2
B
1g
→
2
B
2g
and
2
B
1g
→
2
E
g
transitions respectively. XRD studies confirm a lower degree of crystallinity with higher dopant concentration. EPR spectra exhibit resonance signals due to Cu
2+
ions with characteristic g values, g
ll
= 2.362, and g
⊥
= 2.072, indicates the ground state is d
x2-y2
orbital and the environment is tetragonally distorted octahedral. The improved properties like increased amorphicity and decreased band gap of these Cu doped PVA/MAA:EA polyblend films seems to be desirable for optical and battery applications.
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