Polyaniline–Chromia (PANI–Cr2O3) composites were synthesized by in situ polymerization. The prepared composites were characterized by scanning electron microscopy, X-ray diffraction and Fourier transforms infrared spectroscopy. The structural studies confirm the polymerization of aniline over Cr2O3 particles which results into strong interaction between PANI and Cr2O3 particles. Direct current conductivity of composites increases with increase in temperature. Among all composites, 30 wt% shows high conductivity. The humidity sensing mechanism of the PANI–Cr2O3 composites is studied and change in its resistance with respect to percentage relative humidity ranging from 20 to 95 % is recorded. The humidity sensing studies shows that the change in the resistance is due to the uncurling of polymer chains by the absorption of water vapor which leads to increase in conduction paths. The results indicate better humidity sensing response by the addition of Cr2O3 particles to PANI, among all the composites, 30 wt% composite shows higher sensitivity. 相似文献
In situ polymerization of aniline was carried out in the presence of fly ash (FA) to synthesize polyaniline/ fly ash (PANI/FA) composites.
The PANI/FA composites have been synthesized with various compositions (15, 20, 30 and 40 wt%) of FA in PANI. The composites,
thus synthesized have been characterized by infrared spectroscopy and X-ray diffraction. The morphology of these samples was
studied by scanning electron microscopy. Further the a.c. conductivity of these composites have been investigated in the frequency
range 102–106 Hz. The presence of polarons and bipolarons are made responsible for frequency dependence of a.c. conductivity in these composites.
The Cole-Cole plots indicate clear shift in the distribution of relaxation times as the wt% of FA in PANI changes. These composites
show almost symmetric semicircles of Cole-Cole plots indicating the Debye-type relaxation in their polarization response. 相似文献
Conducting polyaniline-stannous oxide (PAni-SnO) composites were synthesized by the in situ polymerization of aniline in the presence of SnO. The composites formed were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). As there is a greater need for materials with electromagnetic interference (EMI) shielding properties over a large operating frequency band, the present study highlights the dielectric and EMI shielding response of PAni-SnO composites in the microwave frequency range from 8 to 18 GHz (X and Ku bands). All the computations were based on microwave scattering parameters measured by transmission line waveguide technique. The EMI shielding effectiveness (EMI SE), return loss, microwave absorption and dielectric properties of the PAni-SnO composites were evaluated for various wt% of SnO (10, 20, 30, 40 and 50 wt%) in PAni. In X-band, the composites exhibits EMI SE in the range ?18 to ?23 dB, with microwave absorbance of 70–83 % and in the Ku-band, the composites exhibits EMI SE values of ?17.5 to ?22.5 dB with 67–85 % absorbance. Our investigations reveal that the PAni-SnO composites are potential candidates for EMI shielding applications for both the X and Ku bands. 相似文献
Conducting polyaniline (PAni)–antimony trioxide (Sb2O3) composites with different weight percentages (wt%) of Sb2O3 in PAni have been synthesized by in situ chemical oxidative polymerization. The composites were structurally and morphologically characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Measurements of electromagnetic interference (EMI) shielding, complex permittivity and microwave absorbing as well as reflecting properties of the composites were carried out in the frequency range of 8–18 GHz, encompassing the microwave X and Ku bands of practical relevance. All the computations are based on microwave scattering parameters measured by transmission line waveguide technique. It is observed that the presence of Sb2O3 in the PAni matrix affects the electromagnetic shielding and dielectric properties of the composites at microwave frequencies. The composites have shown better shielding effectiveness (SE) in both the X (SE in the range ?18 to ?21 dB) and Ku (?17.5 to ?20.5 dB) bands. ε′ and ε′′ values of the PAni–Sb2O3 composites are in the range of 64–37 and 63–30, respectively, in the frequency range of 8–18 GHz. Dielectric measurements indicated the decrease in dielectric constant with the increase in wt% of Sb2O3. The results obtained for the reflection and absorption coefficients indicated that PAni–Sb2O3 composites exhibit better electromagnetic energy absorption throughout the X and Ku bands. The results indicated that PAni–Sb2O3 composites can be used as potential microwave absorption and shielding materials. 相似文献
In situ polymerization of pyrrole was carried out in the presence of fly ash (FA) to synthesize polypyrrole-fly ash composites (PPy/FA)
by chemical oxidation method. The PPy/FA composites have been synthesized with various compositions (10, 20, 30, 40 and 50
wt%) of fly ash in pyrrole. The surface morphology of these composites was studied with scanning electron micrograph (SEM).
The polypyrrole-fly ash composites were also characterized by employing X-ray diffractometry (XRD) and infrared spectroscopy
(IR). The a.c. conductivity behaviour has been investigated in the frequency range 102–106 Hz. The d.c. conductivity was studied in the temperature range from 40–200°C. The dimensions of fly ash in the matrix have
a greater influence on the observed conductivity values. The results obtained for these composites are of greater scientific
and technological interest. 相似文献
Herein, we report the formation of organic composite coating consists of epoxy (EP) reinforced para toluene sulphonic acid (PTSA) doped polypyrrole (PPy)–manganese iron oxide (MnFe2O2) as an efficient corrosion inhibitor for copper substrates. The PTSA doped PPy:MnFe2O2 nanocomposite was synthesized via in situ polymerization of PPy in the presence of MnFe2O2 nanoparticles. Structural features of the prepared samples were characterized through scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy and thermogravimetric analysis (TGA). The PTSA doped PPy:MnFe2O2 nanocomposite shows excellent conductivity and improved dielectric performance in comparison to pure PPy. The anti-corrosion performance of this organic composite coating was analyzed through Tafel polarization curves, open circuit potential (OCP), corrosion resistance, impedance spectroscopy and oxygen permeability barrier tests. The nanocomposite coating on copper substrate shows superior corrosion protection efficiency (99%) in comparison to pure epoxy (22%). Adhesion strength of the nanocomposite coating shows significant enhancement due to strong dispersions of MnFe2O2 nanoparticles in the host matrix. Owing to its improved conductivity, excellent anti-corrosion performance along with superior mechanical properties, the organic nanocomposite coating reported in this work can potentially be used to protect the conductive copper surfaces from harsh corrosive environments.
Design and development of new generation smart sensors for medical applications have gained considerable interest of research community in the recent past. In this work, we propose the fabrication of highly sensitive paracetamol sensors-based iron oxide nanoparticles intercalated with graphitic carbon nitride (g-C3N4) (GCN) via insitu chemical synthesis. Structural features of the composites were analyzed through SEM, EDX, XRD, FTIR, and UV-Visible spectroscopic techniques. Presence of iron oxide nanoparticles in GCN, significantly improved the conductivity bare GCN from 16 to 125 S cm?1 due to extended π–π conjugation and large surface area in the composite system. The GCN-Iron oxide (GCN-FO) nanocomposite has been employed as an electrochemical sensing platform for non-enzymatic detection of paracetamol. The electrochemical studies and cyclic voltammetry (CV) results shows that the GCN-FO composite exhibit superior electrochemical properties due to their lower values of the oxidation and reduction potentials. Electrochemical impedance spectroscopy (EIS) studies indicate decreased charge-transfer resistance for iron oxide doped GCN composite in compare to base GCN. The improved electrochemical sensing performance of modified GCN-FO composite electrode is attributed to the formation heterojunctions between iron oxide nanoparticles and GCN. The modified GCN-FO electrodes were employed for non-enzymatic electrochemical detection of PR. The GCN-FO composite electrode shows excellent sensitivity towards PR with a LOD 0.3 μM. Furthermore, the modified GCN-FO electrodes show excellent reproducibility, selectivity, stability and anti-interference performance. Due to its low-cost fabrication, superior electrochemical sensing performance, these modified GCN-FO electrodes could be a promising material for the detection of paracetamol at low concentrations.
Conducting polyaniline/γ-Fe2O3 (PANI/FE) composites have been synthesized using an in situ deposition technique by placing fine-graded γ-Fe2O3 in a polymerization mixture of aniline. The composites are characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and infrared (IR) spectroscopy. The electrical properties such as d.c. and a.c. conductivities are studied by sandwitching the pellets of these composites between the silver electrodes. It is observed that the conductivity increases up to a composition of 20 wt.% of γ-Fe2O3 in polyaniline and decreases thereafter. The initial increase in conductivity is attributed to the extended chain length of polyaniline, where polarons possess sufficient energy to hop between favourable sites. Beyond 20 wt.% of γ-Fe2O3 in polyaniline, the blocking of charge carrier hop occurs, reducing conductivity values. The magnetic properties such as hysteresis characteristics and normalized a.c. susceptibility are also measured, which show a strong dependence on content of γ-Fe2O3 in polyaniline. Because of superparamagnetic behaviour of these composites, they may find extensive technological applications, especially for absorbing and shielding applications in microwave frequencies. 相似文献