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Polyester-urea coatings were synthesized from corn oil with the help of a series of reactions in three different compositions by varying the amount of urea. Out of all the synthesized compositions, the best composition was optimized based on various parameters. The optimized composition was used as a matrix and graphene oxide (GO) was incorporated in three ratios, for the formulation of corn oil-based CPEUr@GO nanocomposites. Fourier transform infrared spectroscopy was used to confirm all the reactions. The physico-mechanical properties of CPEU[r.sub.2] coating were found to be the best among all the compositions. Therefore, CPEU[r.sub.2] was selected as a matrix for the inclusion of GO nanosheets to prepare CPEU[r.sub.2]@GO nanocomposites. Thermogravimetric analysis results showed that incorporation of GO enhanced the thermal stability of CPEU[r.sub.2] up to 325[degrees] C. The anticorrosive studies revealed the high impedance value of 6.5 * [10.sup.5] [ohm].[cm.sup.2] in case of CPEU[r.sub.2]@G[O.sub.0.5]. Furthermore, it can be concluded that the inclusion of 0.5 wt% GO proved to be the optimized amount to produce sustainable CPEU[r.sub.2] coatings with good performance. These CPEUr@GO nanocomposite coatings can be used for various protective purposes owing to their excellent physico-mechanical thermal as well as anticorrosive performance. Highlights * Corn oil-based polyester-urea, CPEUr, coatings were synthesized in three different compositions. * The best composition was used as a matrix for the formulation of CPEUr@GO nanocomposites. * Graphene oxide of 0.5 wt% was found to be the optimum quantity required to modify CPEUr matrix. * Thermal stability, mechanical durability as well as corrosion resistance performances were enhanced. * The environment friendly approach is suitable for the development of corrosion protective coatings. KEYWORDS corn oil, graphene oxide, nanocomposites, polyurea, 1 | INTRODUCTION Polyurea (PUr) coating represents a recent advancement in the field of coating technology, within the realm of urethane coatings chemistry. (1) PUr coatings exhibit notable mechanical strength [...]

The rapid use of additive manufacturing (AM) in electronic industry identifies the need of flexible electrically conductive materials suitable for 3D printing. Challenges like buckling of flexible filament and complexity in addition of conductive fillers makes pellet-based extrusion the most suitable alternative for part printing. In the present work, graphite powder is combined with ethylene vinyl acetate (EVA) to print flexible electrically conductive parts. EVA graphite composite with filler loading up to 30% has been investigated for its electrical conductivity and part printability. The composite made was found electrically conductive and suitable for part printing. The parts were printed on a CNC milling machine by using a retrofitted material extrusion tool with nozzle of 0.4 mm diameter and temperature range of 130-140[degrees] C. Parts were printed on a detchable heating bed placed on the milling machine setup. Samples of EVA with graphite filler by weight of 5%, 10%, 20%, and 30% were printed and were checked for electrical conductivity. When the filler content was increased from 10% to 20%, the electrical resistance of the composite was reduced by 62.6%. The presence and uniform dispersion of graphite flakes in the polymer matrix of EVA were guaranteed by the rheological and morphological characterization of the composite. Applications of 3D printable flexible electrically conductive parts lies in numerous domains including biosensors, wearable health monitoring devices, capacitors, field effective transistors, light emitting diodes, solar cells, and electronic displays. Highlights * CNC milling machine-assisted 3D printing is used for part printing. * Graphite powder is combined with EVA pellets. * Pellet-based extrusion is used to print flexible parts. * 3D printability of parts with resistivity 32.64 [ohm]-cm was achieved. KEYWORDS additive manufacturing (AM), ethylene vinyl acetate (EVA), extrusion, flexible electrically conductive polymers, graphite powder, 1 | INTRODUCTION The fundamental advantage of polymer-based additive manufacturing (AM) is rapid fabrication of parts having complicated geometries. Low weight, low cost, nontoxic nature, and workability make polymer a [...]

Multi-walled carbon nanotubes (MWCNTs) were synthesized by a microwave method. MWCNTs had filamentous shapes (10 [micro]m) and were intertwined in bundles (40-60 nm diameter). The rapid oxidation of MWCNTs with a loss of 90% of weight was observed from 530 to 630[degrees]C. 2% Residue was present at 630[degrees]C, which gradually decreased to 1.2% at 1000[degrees]C. In a silicone elastomer, increased thermal conductivity at a concentration of 8% MWCNTs was observed. The highest thermal conductivity of the nano-modified elastomer was 0.48 W/m[degrees]C with 8.0 wt% MWCNTs. The highest electrical conductivity was 2.4 * [10.sup.-5] S [cm.sup.-1] at 8.0 wt% MWCNTs. Both the thermal and electrical conductivities showed percolation behavior with the percolation thresholds at 6 and 5 wt%, respectively. The MWCNTs synthesized by microwave method gave a good power economy in comparison to MWCNTs obtained by chemical vapor deposition (CVD) on NiMg catalyst. Microwave-synthesized MWCNTs showed high stability at a potential of 250 V in an electrical resistance heater application due to the presence of Fe on the surface of MWCNTs. The developed heater can effectively operate at 220 V, which enables the use of the tubes in household appliances, such as heat fans, irons, and washing machines. Highlights * Synthesis of MWCNTs by microwave plasma treatment of ferrocene and graphite. * Characterization of MWCNTs by different techniques. * Concentration dependence of electro- and thermal conductivity of MWCNTs in elastomers. * Electro-physical parameters studies of elastomers modified with MWCNTs. * Heat generation studies in elastomeric matrix with MWCNTs. KEYWORDS ferrocene and graphite, heat dissipation, heaters, MWCNTs, thermal and electrical conductivities, 1 | INTRODUCTION The use of carbon nanotubes is very important in the production of functional materials. (1-3) The developed materials are being used in various applications including biomedicine, (4) [...]

In this work, expandable graphite (EG) was introduced to the composite of polypropylene/magnesium hydroxide (PP/MH) by melt compounding, fire performance, thermal degradation behavior, and acid resistance of the PP/MH/EG composites were investigated. The results demonstrate that the flame retardant efficiency of MH is very low by itself and there is a noticeable synergism between MH and EG in PP. The addition of proper EG can enhance flame retardancy, smoke suppression, and acid resistance of the PP/MH composite significantly at the same time. Replacing 8.7 wt% MH with 8.7 wt% EG reduces the filling grade needed for V-0 from 63 wt% MH to 56.5 wt% MH/EG mixture. The presence of EG on the composite surface hinders acid erosion of MH. There is no chemical reaction between MH and EG. Continuous intumescent char can be produced on the composite surface upon combustion, which is responsible for the much-improved flame retardancy and smoke suppression, regardless of the presence of MH on the surface area. KEYWORDS acid resistance, expandable graphite, flame retardancy, magnesium hydroxide, polypropylene, smoke suppression, 1 | INTRODUCTION As one of the most important thermoplastic polymers, polypropylene (PP) is widely used in many fields, such as plastics pipes, packaging, building materials, household appliances, and the [...]

A new Al.sup.3+ carbon paste ion selective electrode based on N,N'-bis(salicylidene)-1,3-propanediamine (SB-Salpr) was prepared for the quantification of trace Aluminum. The proposed sensor has significant selectivity and sensitivity toward Al.sup.3+ ions in the presence of a wide range of cations including alkaline, alkaline earth, intermediate and heavy metal ions. The use of multi-walled carbon nanotubes (MWCNTs) and nanosilica in the composition of carbon paste sensors caused improvements in their characteristics; these materials have suitable conductivity and can help in conducting signals through the carbon paste sensors. The electrode consisted of 3% of MWCNTs, 0.5% of nanosilica, 25% of paraffin oil, 66.5% of graphite powder and 5% of SB-Salpr ligand. The sensor shows a Nernstian response to Al.sup.3+ ions with a Nernstian gradient of 20.2 ± 0.1 in the concentration range of 1.0 x 10.sup.-6 to 1.0 x 10.sup.-2 M with the detection limit of 2.1 x 10.sup.-7 M. The sensor response is independent of pH in the range of 24 and possesses the advantages of fast response time less than 5 s. According to the obtained results, Al.sup.3+ nanocomposite carbon paste sensor exhibited good selectivity in the presence of a few metal ions. The sensor was effectively used as an indicator electrode in the potentiometric titration of Al.sup.3+ ions with ethylenediaminetetraacetic acid., Author(s): Razieh Sanavi Khoshnood [sup.1], Setareh Akbari [sup.1], Toktam Mashayekhi Chenarbou [sup.2] Author Affiliations: (1) grid.411768.d, 0000 0004 1756 1744, Department of Chemistry, Mashhad Branch, Islamic Azad University, , Mashhad, [...]

Emission spectrometry with an argon arc source, ensuring the significant suppression of interferences with the molecular spectrum of CN, is used for the rapid direct determination of sulfur in pure graphite powders. A method of the time selection of the analytical signal of sulfur at the line 921.286 nm is proposed (signal registration within a certain interval of 9.8 s). The limit of detection for sulfur is 5 x 10.sup.-4 wt %. The analytical range is 5 x 10.sup.-4-2 x 10.sup.-2 wt % and can be expanded to 1 wt %. The time of a single analysis (3 replicate measurements) is 10 min. The work was performed on an MS-300 compact spectrometer, efficient in the range 908-930 nm, with an S13496 diode array photodetector., Author(s): D. O. Antonov [sup.1], E. G. Silkis [sup.2], B. K. Zuev [sup.1] Author Affiliations: (1) grid.439081.7, 0000 0004 0380 8849, Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy [...]

We present a non-covalent compatibilization approach to prepare polypropylene (PP) composites containing expanded graphite (EG) and graphene nanoplatelets (GNPs) by melt compounding. This method involves PP matrix functionalization with pyridine (Py) moieties, which are capable of engaging in [pi]-[pi] interactions with the surface of the EG and GNPs. The addition of 10 wt% of PP grafted with amino-pyridine (PP-g-Py) to neat PP facilitated the break-up of EG particles, by intercalating between their layers and facilitating their separation into smaller tactoids. GNPs were prepared starting from EG through a thermomechanical exfoliation method. Addition of GNPs to PP resulted in well-dispersed platelets having aspect ratios as high as 40, whereas in the presence of the PP-g-Py compatibilizer the matrix contained sub-micron scale platelets. The electrical percolation thresholds were in the vicinity of 6 and 10 vol% in the compatibilized PPEG and PP-GNP composites, respectively, and the maximum value of the electrical conductivity achieved was [10.sup.-1] S/m for the compatibilized GNP composites. Addition of GNPs resulted in increases in the flexural moduli by as much as 95% compared to the unfilled PP, whereas the impact strength remained unaffected up to 10 wt% GNP content. KEYWORDS conducting polymers, functionalization of polymers, polypropylene), microstructure, nanocomposites, 1 | INTRODUCTION Polypropylene (PP) is used in a wide variety of applications ranging from packaging and textiles to light-weight automotive parts. [1] Recently, there has been growing demand for [...]

Raman spectroscopy is a versatile tool to identify and characterize the chemical and physical properties of graphene-based materials (1-4), providing information on graphene structures for fundamental research and for practical device fabrication, as well as demonstrating the first-and second-order modes in intrinsic graphene, as well as the shear, layer-breathing, and the G and 2D modes of multilayer graphene. Professor Ping-Heng Tan from the State Key Laboratory of Superlattices and Microstructures at the Institute of Semiconductors at the Chinese Academy of Sciences is carrying out new research to advance the use of Raman analysis of these materials. We recently interviewed Tan about this work., You have described Raman techniques to determine the number of graphene layers, to probe resonance Raman spectra of monolayer and multilayer graphenes, and to obtain Raman images of graphene-based materials. [...]

In this study, three different sizes of tripolyphosphate-modified expandable graphite (EGP) are prepared and incorporated into rigid polyurethane foam (RPUF) in order to obtain a flame retardant material with low density, good mechanical properties, and hydrophobicity. The influence of particle size on material combustibility, thermal stability, compression strength, pore cell structure, diathermancy, and hydrophobic property is investigated. Synergistic effect between the EGP and ammonium polyphosphate (APP II) is also examined. Results show the limiting oxygen index value and residue yield increase as the EGP size increases. On the contrary, the heat release rate and total heat release decrease as the EGP size increases. In addition, the chemical char formation effect of APP on RPUF is more important than the char formation of the graphite intercalation compounds. EGP and APP show synergistic effect in improving flame retardancy, thermal stability, and hydrophobicity., INTRODUCTION In order to prevent burning and delay fire spread, flame retardants (FRs) are commonly used in polymers [1-6]. The graphite intercalation compound (GIC), namely expandable graphite (EG), is known [...]

A new voltammetric approach was developed for the determination of paracetamol in tablet and syrup samples using chemometric optimization. The method is based on the use of the gold nanoparticles-polyaniline (AuNPs-PA) modified pencil graphite electrode (PGE). Electrode system was fabricated by using the electrochemical reduction of gold on aniline modified pencil electrode to give gold nanoparticles. A 3.sup.3 full factorial design was used to find optimal oxidation conditions of paracetamol on the AuNPs-PA-PGE. The optimal oxidation conditions of drug substance were found as -524 mV for the accumulation potential, 295 s for the accumulation time and pH 8.69 (for the phosphate buffer solution, 0.1 M). The determination of paracetamol was linear in the range of 2.0 x 10.sup.-7-6.0 x 10.sup.-6 M with a detection limit of 5 x 10.sup.-8 M. As a result, the proposed voltammetric approach gave satisfactory results for the determination of the related drug substance in tablets and syrup., Author(s): Remziye Güzel [sup.1], Haslet Eksi [sup.2], Erdal Dinç [sup.3], Ali Osman Solak [sup.4] Author Affiliations: (Aff1) 0000 0001 1456 5625, grid.411690.b, Dicle University, Faculty of Education, Department of Chemistry, [...]

A titanium dioxide modified expendable graphite ([EG.sub.T]) was prepared and characterized. The synergistic effect between [EG.sub.T] and ammonium polyphosphate (APP) on the combustion characteristics and thermal stability of rigid Polyurethane foam (RPUF) were investigated through limiting oxygen index (LOI), vertical-combustion, microscale combustion calorimeter tests, and thermogravimetric/differential thermal gravimetric (TG/DTG) analysis. Results showed that [EG.sub.T] modified RPUF presented better thermal stability and flame retardancy than the normal expandable graphite (EG) modified RPUF. Addition of [EG.sub.T] improved the LOI value of 80RPUF/20[EG.sub.T] from 19.0% to 26.9%. Furthermore, the combination of [EG.sub.T] and APP caused the 80RPUF/10APP/10[EG.sub.T] to exhibit a LOI value of 27.8%, a vertical burning level of V-0 and a total heat release of 16.5 kJ [g.sup.-1]. The research gave a body of evidence for synergistic performance between [EG.sub.T] and APP, and the effect of condensed phase mechanism was believed to be the main reason for such synergistic effect. POLYM. ENG. SCI., 58:2008-2018, 2018., INTRODUCTIONRigid polyurethane foam (RPUF) is extensively used as structural and insulating material and space filling material due to its excellent properties such as low thermal conductivity, high compressive strength, low [...]

The present study explores the potential use of graphene nanoplatelets (GL-GNPs), synthesized from glucose through a new chemical approach that is facile, economical, and eco-friendly alternative to the conventional Hummer's method, as a nanoreinforcement in polymers for the production of lightweight structural polymer nanocomposites. Understanding the interface character of GL-GNPs/Polyamide 12 (PA12) nanocomposites with various nanofiller loadings and how this affects their tensile behavior, are focal points of interest. Results reveal that enhancements in polymer stiffness and strength are superior at low GL-GNPs content than higher contents. This is attributed to higher degree of GL-GNPs exfoliation and increased polymer phase crystallinity. Interestingly, abundant small/imperfect PA12 crystallites have grown on the GL-GNPs surface, strongly interlinking thus the polymer and graphene phases within nanocomposites. The intensity of such crystallites in interface region is the determinant of the nanocomposites' Young's modulus, assessed at small applied tensile stress. While the GL-GNPs-PA12 interfacial bonding is the determinant of yield and ultimate strengths, estimated at medium and high stress levels. Overall, the 1 wt% GL-GNPs/PA12 nanocomposite is considered the optimum. Its low density and good mechanical performance among the previously developed graphene/Polyamide nanocomposites, propose promising future for GL-GNPs-based nanocomposites as ecofriendly and cost-effective lightweight structural material., INTRODUCTION Polymer nanocomposites (PNCs) are defined as polymeric-based materials filled with inclusions, having at least one dimension less than 100 nm. In contrast to the micro-scale fillers, incorporation of nanofillers [...]

Abstract: A flexible, lightweight, and high conductivity current collector is the key element that enables fabrication of a high-performance, flexible lithium-ion battery. Here, we report a thin, lightweight, and flexible [...]

A low-cost and simply fabricated amperometric glucose biosensor based on glucose oxidase (GOx) and 1,10-phenanthroline-5,6-dione (PD) modified graphite rod electrode was developed. The electrode exhibited good electrocatalytic activity with a well-defined hyperbolic dependence of amperometric signal upon glucose concentration in the presence and in the absence of oxygen. The electrode showed a good reproducibility and repeatability with relative standard deviation of less than 3 and 5%, respectively. The interaction of GOx with PD mediator was confirmed by means of UV-'Vis absorbance spectroscopy. Keywords: phenanthroline derivative, 1,10-phenanthroline-5,6-dione, glucose oxidase, glucose biosensor, amperometric sensors, electrocatalytic activity DOI: 10.1134/S1061934816010044, The development of biosensors is one of the most important directions in bioanalytical chemistry, because biosensors could be successfully applied for the determination of some toxic compounds [1] and biologically [...]

Expanded graphite (EG) was added to polylactic acid (PLA) and then fully mixed in a novel elongational mixing device (RMX) to obtain PLA/EG nanocomposites. The operation of the new mixer device is based on the induced multiple passages of material (by means of reciprocating pistons) at different flow speeds through a short capillary die, thus creating convergent/divergent elongational flows. Highly homogeneous materials were obtained at all mixing conditions and particle size ranged from hundred to several hundreds of nanometers. Also, X-ray diffractograms showed different intensity of the characteristic peak of EG (3% wt/ wt EG was kept constant), suggesting partial exfoliation. Furthermore, the molecular weight of processed neat PLA samples was assessed in order to correlate the PLA degradation to morphology and reinforcement mechanisms in the nanocomposites, as a function of the RMX parameters. As well, final flow properties of neat PLA and EG compounds were obtained by dynamic rheology. Thermomechanical degradation of PLA was found to play a major role in the rheology of mixing. On the other hand, PLA nanocomposites presented a storage modulus between 20 and 40% higher than neat PLA. Finally, morphology comparison between the RMX and an internal mixer, at the same mixing energy input, demonstrated a higher dispersive mixing efficiency for the RMX., INTRODUCTION Polymer/Graphite Nanocomposites With the advent of graphene in the last decade [1], research on polymer/graphite nanocomposites has been gaining relevance since graphite is a natural source of this revolutionary [...]

The potentials of using a graphite matrix for laser desorption/ionization from a thin-layer chromatography (TLC) spot is studied. Using a series of pharmaceutical substances with various functional groups and synthetic N-heterocyclic compounds, it was shown that the simple application of graphite onto TLC spots (outlining contour of the spots and shading the spots with a pencil lead) ensured the efficient desorption/ionization of analytes. In most of cases, the recorded mass spectra revealed only [[M + Na].sup.+] and [[M + K].sup.+] ion peaks, doublets of which can be used to determine molecular masses. The appearance of [[M + H].sup.+] ion peaks in some mass spectra may be due to the presence of mineral acids in the samples. The described approach to the application of the 'matrix' onto analyte spots eliminates the danger of spot blurring by a solution or an organic matrix, simplifies the procedure, and shortens the time of sample preparation. Keywords: graphite-assisted laser desorption/ionization, GALDI mass spectrometry, thin-layer chromatography, graphite, pharmaceutical substances, N-heterocyclic compounds DOI: 10.1134/S1061934814140032, INTRODUCTION Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) most often includes the use of various organic matrices. At the same time, the so called matrix-free versions, based on the activation of [...]