Search

New Schiff-base polyesters were prepared from a dihydroxy monomer (E)-1-(5-(4-hydroxy-3-chlorobenzylidene)thiocarbamoylaminonaphthyl)-3-(4-hydroxy-3-chlorobenzylidene)thiourea. The processable pyridine or thiophene-based poly(azomethine–ester)s (PAEs) possess high molar mass of 111 × 103–127 × 103 g mol−1. The 10% weight loss (521–527°C) and glass transition temperature (287–291°C) depicted high thermal stability. Polyaniline (PAN) doped with dodecylbenzenesulfonic acid (PAN/DBSA), prepared by in situ doping polymerization, was blended in solution/melt with PAEs. Field emission scanning electron microscopy of melt blended PAEs/PAN/DBSA showed nanolevel homogeneity of microstructure accountable for superior electrical conductivity (1.9–2.8 S cm−1). The miscible nanoblends also exhibited high heat stability (T10; 500–507°C) and mechanical strength (45.51–48.17 MPa) relative to reported azomethine/PAN-based structures. [ABSTRACT FROM PUBLISHER]

The present work involves the preparation of a new heteroaromatic azo polymer, poly(thiourea-azo-ether; PTAE) using 4,4′-oxydiphenyl bis(thiourea) and diazonium salt solution of 2,6-diaminopyridine. The polymer was easily processable using polar solvents and had high molar mass of 33 × 103 g mol−1. Various concentrations of azo filler and poly(styrene-butadiene-styrene; SBS) blends were then blended in solution phase. The effect of PTAE on processing, conductivity, morphology and thermophysical properties of elastomeric blends was investigated. Field-emission scanning electron microscopic micrographs of SBS/PTAE blends revealed fine dispersal of filler, good adhesion with the matrix and the development of conducting pathways. Accordingly, filler content from 10 to 60 wt% increased the conductivity from 0.77 × 10−1 to 1.43 S cm−1. Ultimate tensile strength of SBS/PTAE (26.94–28.12 MPa) was improved relative to pure SBS. A relationship between PTAE loading and thermal stability of the materials was also observed. The temperature at 10% gravimetric loss was increased from 461 to 499°C, while the glass transition temperature was enhanced from 135 to 147°C. Thermal and conducting data showed better results relative to pure elastomer but lower than the conducting filler. Fine balance of properties renders new materials better than the existing elastomeric blends used in a number of applications. [ABSTRACT FROM PUBLISHER]

A high molecular weight (27 × 103 gmol−1) poly(azo-ether-imide) has been fabricated in this study. Well-aligned poly(azo-ether-imide) fibers and poly(azo-ether-imide)/multi-walled carbon nanotube nanofibers-based nanocomposite were then produced by electrospinning via self-reinforcement. Transmission electron microscopy showed that the poly(azo-ether-imide)–multi-walled carbon nanotube electrospun nanofibers were uniform and almost free of defects. Scanning electron microscopy indicated the wrapping of matrix over the bundles of nanofibrs. The as prepared electrospun nanofibers were utilized as homogeneous reinforcement to enhance the tensile strength and toughness of films. The tensile strength and tensile modulus of poly(azo-ether-imide) film reinforced with 3 wt% poly(azo-ether-imide)–multi-walled carbon nanotube nanofibers were 18% and 23% higher as compared to those of the poly(azo-ether-imide) film reinforced with 3 wt% neat poly(azo-ether-imide) nanofibers. The significant enhancement in the overall mechanical properties of the poly(azo-ether-imide)–multi-walled carbon nanotube nanofibers reinforced polyimide films was ascribed to good compatibility between the electrospun nanofibers and the matrix as well as high nanofiber orientation in the matrix. The homogeneous alignment of poly(azo-ether-imide)/multi-walled carbon nanotube nanofibers was also studied using scanning electron microscopy micrographs. Moreover, the thermal stability of poly(azo-ether-imide)/multi-walled carbon nanotube nanofibers reinforced polyimide was superior having 10% gravimetric loss at around 602–617℃ and glass transition temperature in the range of 241–263℃ relative to the neat polymer and poly(azo-ether-imide) nanofiber-based system. This study demonstrated the fabrication of high performance and high toughness polyimide nanocomposites by using this facile self-reinforcement method. [ABSTRACT FROM PUBLISHER]

Single and multilayered nanocomposites of polyaniline (PANI), polypyrrole (PPy), Epoxy, polystyrene (PS) and functionalized carbon nanotubes (MWCNT) have been synthesized as PANI/MWCNTs, PPy/MWCNTs, Epoxy/MWCNTs, PS/MWCNTs, PANI/PPy/MWCNTs, PANI/PPy/Epoxy/MWCNTs and PANI/PPy/Epoxy/PS/MWCNTs. Layering of matrices on filler surface through layer-by-layer oxidative polymerization was confirmed by Fourier transform infrared spectroscopy. According to SEM, doubly layered PANI/PPy/MWCNTs revealed finely dispersed granular layer of polypyrrole over the surface of polyaniline. Thermogravimetric analysis of multilayered PANI/PPy/Epoxy/PS/MWCNTs showed degradation at enhanced temperature 400–750°C and char yield 45% at 900°C. Improvement in glass transition of layered material was observed from 275°C (PANI/PPyMWCNTs) −354°C (PANI/PPy/Epoxy/PS/MWCNTs). [ABSTRACT FROM PUBLISHER]

Poly(azo-pyridyl-urethane)/multi-walled carbon nanotube (PAPU/MWCNT) nanocomposites were prepared by first synthesizing polyurethane followed by solution dispersing MWCNT in the matrix. We have used two different MWCNTs: the first set of MWCNT contained carboxylic acid group (MWCNT-COOH) and the second set contained acid chloride group (MWCNT-COCl). Afterward, these MWCNT particles were used in the preparation of PAPU/MWCNT nanocomposites. In the first set of nanocomposites, MWCNT-COOH and PAPU were just physically mixed and were designated as PAPU/MWCNT-A. In the second set of nanocomposites, PAPU chains were tethered onto the surfaces of MWCNT-COCl particles and designated as PAPU/MWCNT-AC. Two types of nanocomposites were thus fabricated, including acid functionalized nanotube-based non-tethered PAPU/MWCNT and acid chloride functionalized MWCNT-based tethered system. We have incorporated hydroxyl end-terminated polyurethane via “grafting to” approach to acid chloride functional MWCNT through esterification. Fourier transform infrared spectra confirmed that the matrix was covalently attached to sidewalls of nanotube. Various nanotube loading levels and surface-modified groups were considered to regulate mechanical, thermal and electrical performance of PAPU/MWCNT. The experimental results showed that a moderate loading level of 5 wt. % MWCNT produced the maximum tensile strength (63.1 MPa) in tethered nanocomposites, while the presence of surface carboxylation of MWCNT relatively decreased the tensile strength (49.7 MPa). Comparative studies based on scanning and transmission electron microscopy of the chemically bonded samples revealed unique nano-fibriller morphology. Dynamic mechanical analysis of nanocomposite films showed an increased segmental rigidity with Tg of 144–153℃ in the tethered system relative to pristine PAPU (133℃). Addition of acid chloride functional MWCNT also contributed to an enhancement in the conductivity (2.9–4.7 S cm−1), relative to PAPU/carboxylated MWCNT (2.0–2.7 S cm−1). [ABSTRACT FROM PUBLISHER]

Nanocomposite composed of amine-terminated polyamide (an aramid)/bisphenol A diglycidyl ether epoxy matrix and functionalized and non-functionalized multi-walled carbon nanotube have been fabricated. Polyamide/bisphenol A diglycidyl ether/multi-walled carbon nanotube nanocomposite was cured at 120℃ with different filler content. In order to investigate the influence of functional filler on nanocomposite properties, morphological, mechanical and thermal profile of polyamide/bisphenol A diglycidyl ether nanocomposite with varying multi-walled carbon nanotube content were studied. Functional multi-walled carbon nanotube-reinforced nanocomposite showed greater strengthening at all weight percent as they actively control the failure mechanism; 5 wt% functional multi-walled carbon nanotube-based sample showed 62% improvement in toughness i.e. area under the stress–strain curve (35.6 J/m3) relative to non-functional (13.7 J/m3) nanocomposite. The ultimate tensile strength also improved from 39.2 to 59.7 MPa. The multi-walled carbon nanotube ratio was an interesting feature significantly influencing the properties of polyamide/bisphenol A diglycidyl ether/multi-walled carbon nanotube due to the contribution of hydrogen bonding and π-π staking between the matrix and filler. Thermal stability consistently increased with amalgamation of functional multi-walled carbon nanotube in the polyamide/bisphenol A diglycidyl ether matrix (T0 523–565℃; Tg 247–253℃) over polyamide/bisphenol A diglycidyl ether /non-functional multi-walled carbon nanotube (T0 499℃; Tg 246℃). Novelty of the research lies in exclusive architecture, exceptional heat stability and mechanical properties of aramid/epoxy-based nanocomposite. [ABSTRACT FROM PUBLISHER]

In this effort, Quickstep, a relatively a new technique, have been employed for manufacturing of composite materials. The cure schedule provided by a prepreg manufacturer is usually designed for autoclave or other traditional processing techniques and thermosetting resin systems are formulated for ramp rate curing 2-3 K min−1. While in case of Quickstep processing, ramp rates of 15 K min−1 can be achieved, thus changing the chemorheology of resin. The cure process of 977-2A carbon/epoxy composites was evaluated for Quickstep processing using differential scanning calorimetry (DSC), dynamic mechanical and thermal analysis, and Fourier transformed infrared and results were compared with cure cycle employed for autoclave curing. Optimum hold time for Quickstep processing at upper curing temperature (180°C) was determined using DSC. The hold time of 120 min at 180°C was found to be suitable for Quickstep cure cycle, producing a panel of similar degree of cure to that achieved through autoclave processing schedule. Final degree of cure was dependent on time spent at upper cure temperature and slightly on initial steps of the cure cycle which was used to control the resin flow, fiber wetting, and void removal. Quickstep processed samples exhibited higher Tg and crosslink density and similar molecular network structure to the autoclave cured samples. POLYM. ENG. SCI., 54:887-898, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

An aromatic azo-polymer, poly(thiourea-azo-naphthyl), has been synthesized using 1-(5-thiocarbamoylaminonaphthyl)thiourea and diazonium salt solution of 2,6-diaminopyridine. Poly(thiourea-azo-naphthyl) was easily processable using polar solvents and had high molar mass, 57 × 103 g/mol. Electrically conducting and mechanically and thermally stable polymer/multi-walled carbon nanotube nanocomposites were obtained via melt processing technique. Fine distribution of multi-walled carbon nanotubes in a polymer matrix played an essential role in the preparation of polymer/multi-walled carbon nanotube nanocomposites based on interfacial interaction between multi-walled carbon nanotubes and polymer matrix. Field emission-scanning electron microscopy images revealed good dispersion of filler and adhesion of matrix on the surface of multi-walled carbon nanotubes. Accordingly, increasing the amount of multi-walled carbon nanotubes from 1 to 5 wt% increased the electrical conductivity from 2.42 to 4.11 S cm−1. Percolation behavior of the composite was also studied. Tensile modulus for 1 wt% nanocomposite was 4.2 GPa, which increased up to 6.8 GPa on 5 wt% filler addition. A relationship between nanotube loading and thermal stability of the materials was also observed. Ten percent gravimetric loss increased from 502℃ to 538℃ in the presence of 1 wt% multi-walled carbon nanotube. Similarly, glass transition increased from 227℃ to 245℃ in the presence of 5 wt% multi-walled carbon nanotube. Enhancement of the physical properties of multi-walled carbon nanotube-reinforced polymer nanocomposites was accredited to the non-covalent interactions (π–π interactions and secondary bond forces). [ABSTRACT FROM PUBLISHER]

The synthesis, characterization and photocatalytic performance of non-traditional Al2O3-TiO2-based photocatalysts is reported. Al2O3-TiO2support was loaded with various fractions of CuO and ZrO2. A sound agreement was observed between the bandgaps of synthesized powders measured by UV-Visible diffuse reflectance spectroscopy (DRS) in the solid phase and UV-Visible spectroscopy in the aqueous medium. X-ray diffraction (XRD) analysis revealed the composite nature of the catalysts with the retention of individual identity of each component. The average crystallite size of the individual component was found to be in the range of 20 to 40 nm. Scanning electron microscopy (SEM) analysis authenticated the presence of CuO and ZrO2at the surface of Al2O3-TiO2support, while Rutherford Back Scattering Spectroscopy (RBS) confirmed the quantity of the modifiers as per theoretical calculations. The composites showed an enhanced photocatalytic activity in sunlight compared to Al2O3-TiO2for the degradation of dyes. Efforts were made to elucidate the enhanced sunlight response of the synthesized composite catalysts compared to Al2O3-TiO2. As monitored by ion chromatography (IC), the synthesized photocatalysts completely mineralized the dyes leaving behind inorganic ions in solution. The kinetics of photocatalytic degradation of dyes was evaluated for optimum correlation with the existing models. The stability of the photocatalysts against the photo-corrosion was monitored by analyzing the samples for respective metals in solution after sunlight exposure. Supplemental materials are available for this article. Go to the publisher's online edition of theJournal of Environmental Science and Health, Part A, to view the supplemental file. [ABSTRACT FROM AUTHOR]

A new aromatic azo-polymer, poly(thiourea-azo-naphthyl) (PTAN), has been synthesized using 1-(5-thiocarbamoylaminonaphthyl)thiourea and diazonium salt solution of 2,6-diaminopyridine. PTAN was easily processable using polar solvents and had high molar mass 57 × 10 3 g/mol. Electrically conducting, mechanically and thermally stable rubbery blends of poly(styrene-butadiene-styrene) (SBS) triblock copolymer and PTAN were produced by solution blending technique. FESEM of SBS/PTAN blends revealed nano-scale dispersion of the conducting filler showing good adhesion between the matrix and PTAN. Remarkable effects of azo-content on the conductivity of SBS-based blends have been observed. Accordingly, PTAN loading from 10 to 60 wt% increased the conductivity from 1.24 to 1.66 S/cm. Relationship between PTAN loading and thermal stability of the materials was also investigated. With increasing the PTAN content, 10% gravimetric loss was increased from 484 to 500 °C, while glass transition was enhanced from 119 to 126 °C. Thermal and conducting data of the blend showed better results relative to pure elastomer but were lower than those of the conducting filler. Similarly, the tensile strength (57.35–62.33 MPa) of SBS/PTAN was improved relative to there of SBS. Fine balance of properties renders new materials fairly better than the existing elastomeric blends used in a number of applications. [ABSTRACT FROM AUTHOR]

This study describes the effect of annealing at different temperatures (400–600 °C) on structural, optical and electrical behaviors of pure and Mg doped tin oxide thin films grown on the glass substrate by electron beam evaporation technique. The transformation of tetragonal to orthorhombic form due to annealing, introduced a change in the optical and electrical properties of pure and Mg doped tin oxide thin films. X-ray diffraction studies or analysis revealed the phase transformation and change in the crystalline size with increase in the annealing temperature. The morphology and roughness of the thin films were studied by Atomic force microscopy. Optical band gap increased with annealing temperature confirms the improvements of crystallinity. The quality of thin films transparency was investigated by UV/Vis-spectroscopy. Photoluminescence of pure and Mg doped tin oxide thin films shows two extra peaks one at 486 nm and other at 538 nm is due to the crystal defect created as a result of annealing temperature. These peaks became stronger and shifted to longer wavelength with increasing the annealing temperature. The complex plot (Nyquist plot) showed the data point laying on two semicircles and the resistance of grains and grain boundaries increases with the increase in annealing temperature for both pure and Mg doped tin oxide thin films. [ABSTRACT FROM AUTHOR]

In the current study, poly(thioureaamide) (PTA) was prepared from isophthaloyl diisothiocyanate and p-phenylenediamine using a facile condensation technique. Fourier transform infrared and proton nuclear magnetic resonance spectroscopic analyses confirmed the structure of the polymer obtained. PTA was then used as a matrix to synthesize organic hybrid materials. In this regard, the functionalized and nonfunctionalized multiwalled carbon nanotubes (CNTs) were utilized as fillers in this work to prepare the nanocomposites. In PTA and functional CNTs system, better compatibility between the organic matrix and the filler was confirmed using field effect scanning electron microscope. The micrographs revealed that the nanotubes were well dispersed in the matrix and packaging of polymer over the surface of functional CNTs. The interaction between polymer chains and functional reinforcement produced mechanical and heat-stable nanocomposites. The tensile strength of the functional CNT-based hybrids 53.21–57.11 MPa was improved as compared with the nonfunctional system (32.79 MPa). The 10% gravimetric loss (513–556°C) and the glass transition temperature of PTA/functional CNTs (184–191°C) depicted a considerable improvement over PTA/nonfunctional CNTs. The results showed the enhanced interactions between the two phases in PTA/functional CNT-based nanocomposites relative to PTA/nonfunctional CNTs. [ABSTRACT FROM AUTHOR]

A new dihydroxy monomer, ( E)-1-(4-(4-(4-hydroxybenzylidene)thiocarbamoylaminobenzyl)phenyl)-3-(4-hydroxybenzylidene)thiourea, was synthesized and polymerized with thiophene-2,5-dicarbonyl/terephthaloyl chloride. The structural characterization of the resulting polymers was carried out using spectral techniques (Fourier transform infrared and 1H NMR) along with a physical property investigation. Novel polyesters are readily soluble in various amide solvents and possess high molar mass of 112 × 103-133 × 103 g mol−1. The thermal stability was determined via 10% weight loss to be in the range 519-523 °C and the glass transition temperature was 286-289 °C. Electrically conducting poly(azomethine-ester)- blend-polyaniline blends were prepared using mash-blending and melt-blending techniques. Materials obtained using the conventional melt-blending approach generated an efficient conductive network compared with those produced by mash blending. Field emission scanning electron microscopy revealed a nano-blend morphology for the melt-blended system owing to increased physical interactions (hydrogen bonding and π-π stacking) between the two constituent polymers. Miscible blends of thiophene-based poly(azomethine-ester)- blend-polyaniline had superior conductivity (1.6-2.5 S cm−1) and thermal stability ( T10 = 507 °C) even at low polyaniline concentration relative to reported thiophene/azomethine/polyaniline-based structures. The new thermally stable and conducting nano-blends could be candidates for various applications including optoelectronic devices. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this study polymer-matrix composite has been processed using autoclave and Quickstep techniques. A phenomenological approach was adopted for the optimization of cure cycle for Quickstep of an aerospace grade epoxy composite (Cycom 977-2A carbon/epoxy prepregs). Though there are reports concerning the processing and properties of materials using Quickstep technique, little work has been reported on the design of optimized cure cycle for Quickstep processing based on rheology, ultrasonic testing, and mechanical characterization. A step by step account is provided in this study, describing the introduction, balancing and combination of isothermal dwell periods and temperature ramps in order to control the resin viscosity. All the panels manufactured were qualitatively assessed using ultrasonic C-scan and afterwards fiber and void content, panel thickness, flexural strength, and interlaminar shear strength (ILSS) were assessed and compared with those obtained from traditional autoclave- and oven-cured laminates. The Quickstep panel properties produced from optimized cure cycle was superior to oven curing and was comparable with autoclave. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

In the present work, nanocomposites of a matrix composed of poly(thiourea-amide) (an aramid)/epoxy (thermoset) and CNTs were fabricated. The hybrids were prepared byin situpolymerization using functionalized and nonfunctionalized CNTs. Amine-terminated poly(thiourea-amide)/epoxy/CNTs hybrids were cured at 120°C with different CNTs content. Chemical linking between amine terminated poly(thiourea-amide) and epoxide group of Bisphenol A diglycidyl ether (DGEBA) formed PTA/DGEBA complex. Hydrogen bonding of PTA with functionalized CNTs was expected to improve the hybrid characteristics. Tensile strength of functional hybrids ranged 57.36–60.68 MPa. 10% gravimetric loss (569–590°C) and Tgof PTA/DGEBA/functional CNTs (235–238°C) showed improvement over PTA/DGEBA/nonfunctional CNTs. [ABSTRACT FROM AUTHOR]

Series of aromatic polyamides containing azo groups have been synthesized by the phosphorylation polycondensation of a new dicarboxylic acid (E)-1-(4-(4-(3-carboxypyridylazo)thiocarbamoylaminophenyl-sulfonyl)phenyl)-3-(3-carboxypyridylazo)-thiourea and various diamines. Poly(azo-sulfone-amide)s (PASAs) were characterized using spectroscopic techniques, solubility, molar mass, electrical conductivity, mechanical strength, nonflammability, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies. PASAs possessed fine solubility in polar solvents and high molar mass 70 × 103–75 × 103 gmol−1. These polyamides showed fibrous structure according to field-emission scanning electron microscopy (FESEM). Thermal and nonflammability data indicated that PASAs were fairly stable above 500°C having initial weight loss of around 525–531°C, 10% of gravimetric loss in the range of 542–563°C, own high glass transition temperature 257–267°C and limiting oxygen index (LOI) values (35–47%). The polymers also demonstrated higher tensile strength (61.10–74.29 MPa) and elongation at break (1.49–1.57). FESEM images displayed fibrous morphology of the PASAs. Moreover, polyamides showed superior electrical conductivity (1.45–1.92 S cm−1). Fine balance of the properties render the new PASAs potential engineering plastics for a number of aerospace relevance. [ABSTRACT FROM AUTHOR]

The present work initially deals with the fabrication of a new generation of polyesters (bearing thiophene, azomethine, thiourea and ether moieties) and subsequent blending with polyaniline (PAN) exhibiting extremely valuable nanoblend characteristics. Few poly(azomethine-thiourea-ester)s (PATEs), by the polycondensation of a new diol 4,4′-oxydiphenyl bis((E)-1-(4-hydroxobenzylidene)thiourea) with thiophene-2,5-dicarbonyl/terephtaloyl chloride, were synthesized. The polymers obtained were characterized by Fourier-transform infrared, proton-nuclear magnetic resonance, solubility, solution viscosity, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry and wide-angle x-ray diffraction. The polymers exhibited high molar mass (77–89 × 103) and thermal stability (T10 528–531°C, glass transition temperature (Tg) 265–268°C). Then the electrically conducting blends, of PAN dispersed in the PATEs matrix, were prepared by mash-blending and melt-blending techniques. Materials obtained by conventional melt-blending approach generated an efficient conductive network compared with those produced by mash blending. Field emission scanning electron microscopy images displayed nanoblend morphology of the melt-blended system, owing to increased physical interactions (hydrogen bonding and π–π stacking) between the two polymers. Moreover, miscible blends of thiophene-based PATE/PAN led to superior conductivity (1.5–2.1 S/cm) and heat stability (T10 503°C) even at low PAN concentration relative to previous thiophene, azomethine or PAN-based structures. [ABSTRACT FROM PUBLISHER]

New thermoplastic segmented poly(azo-urethane)s (PAUs) have been synthesized by one-step polycondensation from aromatic diazo-diol, (E)-1-(4-(4-(3-hydroxypyridyl-azo)thiocarbamoylaminobenzyl)-phenyl)-3-(3-hydroxypyridylazo)thiourea, as chain extenders, phenylene diisocyanate and 20–60 mol % polyethylene glycol (PEG) with the molecular weight of 2000 g/mol. The effect of diazo-diol used in the structure and some physicochemical, thermal and mechanical properties of the segmented polyurethanes were studied. The structure was examined by proton nuclear magnetic resonance (1H NMR) and Fourier-transform infrared spectroscopy (FTIR) analyses. Polyazos were the products with good processability and high molar mass in the range 120 × 103–135 × 103 g/mol. Thermal properties, investigated by thermogravimetric analysis and differential scanning calorimetry indicated that PAUs up to 40 mol % polyol were fairly stable above 530°C, having initial weight loss of around 528–539°C, 10% gravimetric loss in the range 553–567°C and own high glass transition temperature 259–264°C. The polymers also demonstrated higher tensile strength (56.53–63.83 MPa) and elongation at break (1.58–1.63). However, compared with typical polyurethanes, PAUs with lower polyol content displayed higher Tgs, heat and mechanical stability owing to warily designed rigid hard segment structure. [ABSTRACT FROM PUBLISHER]

In this endeavor, a new type of nanocomposites has been developed from conducting organic polymers (layer-by-layer in situ polymerization of various monomers) and functionalized multiwalled carbon nanotubes (MWCNTs). Initially, functionalization of MWCNTs was achieved by sulfuric acid (H2SO4):nitric acid (HNO3) and HNO3:hydrogen peroxide treatment. A comparative study regarding the synthetic, morphological, and electrical profiles of raw MWCNTs (R-MWCNTs), pure-MWCNTs (P-MWCNTs), functionalized MWCNTs (F-MWCNTs), and polyaniline/polypyrrole/polythiophene-F-MWCNTs (PANI/PPy/PTh/F-MWCNTs) nanocomposites was successfully carried out. Introduction of functional groups on the surface of MWCNTs was confirmed by Fourier transform infrared spectra. Energy dispersive x-ray spectroscopy and Rutherford back scattering were employed for the elemental analyses. Morphology of the obtained hybrid material was studied via scanning electron microscopy and their thermal stability was investigated using thermogravimetric analysis. The dielectric constant and electrical conductivity were also measured. Result exploration revealed that F-MWCNTs were well functionalized ensuing interfacial entrapment between the carbon nanotubes and the matrix. In addition, the layer-by-layer deposition of PPy/PANI/PTh polymers enhanced the electrical conductivity of material relative to the neat ones. Besides, the improved thermal stability of composite was acquired when compared with the homopolymers. [ABSTRACT FROM AUTHOR]

An ultra efficient cobalt tailored silver and nitrogen co-doped titania (TiON/Ag2O/Co) visible nanophotocatalyst is successfully synthesized using modified reverse micelle processing. Composition, phase, distribution of dopants, functional group analysis, optical properties and morphology of synthesized materials are investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) based techniques, Diffuse reflectance spectroscopy (DRS) and others. Charge states of Titanium (Ti) and Silver are explored through core-loss electron energy loss spectroscopy (EELS) analysis and X ray photoelectron spectroscopy (XPS). Our characterization results showed that the synthesized nanophotocatalyst consisted of antase phased qausispherical nanoparticles that exhibited homogeneous distribution of dopants, large surface area, high quantum efficiency and enhanced optical properties. At lower content of doped Co ions, the TiON/Ag2O responded with extraordinary photocatalytic properties. Moreover, Co tailored nanophotocatalyst showed remarkable activity against E. coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus feacalis. [ABSTRACT FROM AUTHOR]

Heavy metal's release without treatment poses a significant threat to the environment. Heavy metals are non-biodegradable and persistent. In the present study the ash of water hyacinth (Eichhornia crassipes), was used to remove six metals from aqueous solutions through biosorption. Results of batch and column experiments showed excellent adsorption capacity. Removal of lead, chromium, zinc, cadmium, copper, and nickel was 29.83, 1.263, 1.575, 3.323, 2.984 and 1.978 μgg-1, respectively. The biosorptive capacity was maximum with pH >8.00. Desorption in μgg-1 of ash for lead, chromium, zinc, cadmium, copper, and nickel was 18.10, 9.99, 11.99, 27.54, 21.09, and 3.71 respectively. Adsorption/desorption of these metals from ash showed the potential of this technology for recovery of metals for further usages. Hydrogen adsorption was also studied with a Sievert-type apparatus. Hydrogen adsorption experiments showed significant storage capacity of water hyacinth ash. [ABSTRACT FROM AUTHOR]

We report an interesting finding that the catalytic performance of supported Ni/γ-Al2O3 catalyst towards selective catalytic hydrogenation of edible oils can be greatly enhanced by pretreatment of the γ-Al2O3 support before catalyst preparation. Calcination of Al2O3 at appropriate temperatures results in the highly dispersive nano Ni/γ-Al2O3 catalyst and thus improves the catalytic performance. Catalyst sample of improved physical properties prepared by modified procedure using γ-Al2O3 as support was characterized using powder XRD, SEM, BET, FTIR, Particle size analyzer, CO-chemisorption, and TPR studies. These studies indicate that support pretreatment results in enhancing catalyst dispersion with increase in Ni loadings. Clearly the effect of surface area and particle size of the catalyst coupled with surface properties and method of catalyst preparation on the saturated fats content of the foods like margarines prevails. [ABSTRACT FROM AUTHOR]