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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 [...]

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 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 [...]

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 [...]

In this study, the flammability characterization and synergistic effects of different particle size of expandable graphite (EG) with modified magnesium hydroxide (MH) in flame-retardant polypropylene (PP) composites were studied by limiting oxygen index (LOI), UL-94 test, ther-mogravimetric analysis (TGA), and fourier transform infrared (FTIR) spectroscopy. The results showed that the particle size of EG had a great effect on the flammability of the PP/MH/EG composites. The EG2 with smaller particle size could apparently increase the LOI value and improved the UL-94 flammability properties rating of the PP composites. The data obtained from the TGA and FTIR curves indicated that the thermo-oxidative stability of PP/MH/EG composites increased with decreasing particle size of EG. And the smaller the particle size of EG, the higher the residues of the composite. POLYM. ENG. SCI., 47:1756-1760, 2007. © 2007 Society of Plastics Engineers, INTRODUCTION Traditionally, halogen containing compounds, alone or in conjunction with antimony trioxide, are the main flame retardants (FR) of polyolefins (PO). There is an increasingly restriction about the use of [...]

Poly(methyl methacrylate) (PMMA)/expanded graphite composite has been made via an in situ polymerization of methyl methacrylate(MMA) in the presence of expanded graphite obtained by rapid heating of the graphite intercalation compound (GIC). The composite was then blended with poly(vinyl chloride) (PVC) to form an electrically conducting composite. SEM, TEM and XRD showed that the graphite had been dispersed throughout the polymer matrix in the form of nanosheets with thicknesses of about 20 nm. The resulting composite showed excellent electrical conductivity despite a low concentration of graphite. The transition from an electrical insulator to an electrical semiconductor for the composite occurred when the graphite content was 3.5 wt%, much lower than that of conventional conducting polymer composites. Conductivity reached a maximum of [10.sup.-4] s/cm at a graphite concentration of 5.0 wt%. This improvement of conductivity could be attributed to the high aspect ratio (width-to-thickness) of the graphite na nosheets dispersed in the polymer matrix., INTRODUCTION Graphite, which is naturally abundant, has been widely used as a conducting filler in preparing conducting polymer composites (1, 2). Conventional graphite fillers are usually micro-diameter powders. In order [...]

Silver-graphite materials are commonly used as arcing contacts is prevalent in both arcing and sliding applications. One such material, Graphite, has the ability to prevent sticking or welding and stops the formation of insulating compounds which could cause high contact resistance. On the other hand, silver is a very good electrical conductor and does not form stable oxides. The effects of graphite particles on the arc erosion behavior of silver-graphite materials are discussed.

We report the synthesis of tubular graphite cones using a chemical vapor deposition method. The cones have nanometer-sized tips, micrometer-sized roots, and hollow interiors with a diameter ranging from about 2 to several tens of nanometers. The cones are composed of cylindrical graphite sheets; a continuous shortening of the graphite layers from the interior to the exterior makes them cone-shaped. All of the tubular graphite cones have a faceted morphology. The constituent graphite sheets have identical chiralities of a zigzag type across the entire diameter, imparting structural control to tubular-based carbon structures. The tubular graphite cones have potential for use as tips for scanning probe microscopy, but with greater rigidity and easier mounting than currently used carbon nanotubes., Owing to their unique mechanical properties and atomic structures, carbon nanotubes (CNTs) have various potential applications, such as probes for scanning probe microscopy (1-3), field electron-emitting sources (4-6), and tiny [...]

A scanning tunneling microscopy (STM) experiment can be used to teach physical chemistry undergraduate students about surface oxidation kinetics, exploring the kinetics of the oxidation of a carbon surface. The students first do an experiment introducing them to STM and the crystal structure of graphite.

The effects of iron content and initial fractional density of the preforms on deformation behavior are investigated thoroughly by using graphite as a lubricant. It was found that the preforms of higher iron content show higher values of deformation properties like the axial stress and the Poisson's ratio than less/without iron preforms provided that the initial fractional density taken is kept constant.

Researchers at University of Manchester, U.K., say graphene has the potential to replace carbon fiber in high-performance materials used to build aircraft. Graphene, a 2-D layer of carbon atoms that [...]

The Dixon Ticonderoga 1388 Number 2 graphite pencil is a suitable substitute for expensive platinum in voltaic cell measurements. The pencil with graphite revealed on both ends can be used as an electrode for the measurement of galvanic cell potentials and the results obtained are in good agreement with those of platinum. Good reproducibility has also been documented. Comparison of platinum and pencil electrode results after multiple uses revealed that solution absorption was not a problem.

A number of methods have been developed for the synthesis of single-and multiwalled carbon nanotubes. However, these methods typically require high temperatures and complex procedures, or they use metallic catalyst [...]

The world market for automobile gaskets is estimated at around $3 billion. Industry tends to use technically over-engineered systems, which result in higher costs. A gasket material has been introduced which may offer savings in both material and manufacturing costs. Expanded graphite has been used successfully, but it can be brittle, however when synthesized with Kevlar, its operating envelope is extended. The new material combines the strength and durability of Kevlar with the sealing abilities and temperature performance of graphite.

Copper wires can be soldered to graphite easily without losing conductivity by electrodepositing copper at the connection site and then soldering the wire to the copper. Other techniques such as silver glue increase the resistance of the copper-graphite connection while the electrodeposit technique does not introduce any more resistance because of the copper and solder alloy's high compatibility. This technique is important because of graphite's common use as electrode material.