Carbon Nets Research Articles

Influence of panel density on the characteristics of novel multifunctional particleboard

ABSTRACT A novel approach to produce a multifunctional particleboard (PB) with lower density and high electrical conductivity is presented. To this end, woven carbon nets with a perforated structure were inserted into the panel structure during mat formation. PB with different densities of 600, 650, 700, and 750 kg/m3 were produced without and with carbon nets having a mesh size of 225 mm2. The physical and mechanical properties of the PB were evaluated according to the EN310, EN319 and EN317 standards, respectively, and the electrical properties were measured using the developed “four-probe method”. It was found that, increasing the panel density from 600 to 750 kg/m3 led to a significant improvement in flexural strength and internal bond strength but had a negative effect on the thickness swelling of the PB. The results also showed that by incorporating carbon nets into the panel structure, the insulated PB was transformed into an electrically conductive panel suitable for furniture applications. The electrical resistance of the panels was significantly reduced by increasing the panel density to 750 kg/m3. The carbon nets also significantly improved the flexural properties of the composites and had some negative effects on the internal bond strength. The piece of furniture produced also confirmed the suitability of the multifunctional PB for illuminating the LED lamps and integrating the cell phone charging technology into the panels.

Development of electrically conductive wood‐based composites using carbon nets

AbstractA novel conductive composite material was developed using woven carbon nets. For this purpose, carbon nets with different mesh sizes of 25, 100, 225, and 400 mm2 were woven, using two different carbon yarns with widths of 2 and 0.5 mm. The woven carbon nets were used before and after the core layer formation during mat forming of the particleboard. It was found that the insertion of carbon nets into the panel structure not only transforms insulated particleboard into a highly conductive composite but also significantly improves the flexural properties of the composite. However, the internal bond strength and physical properties of the composites were negatively affected by the presence of carbon nets in the panel structure, although their values were still above the minimum requirements of the standard values. Increasing the mesh area of the carbon nets and using thinner carbon yarns to weave the nets had a negative effect on the electrical and mechanical properties of the composites. In addition, a demonstration object was made of conductive composites to integrate lighting and a smartphone charging port into the object and prove the applicability of the developed composites for the furniture industry.Highlights Composites with carbon nets with smaller mesh area showed higher conductivity. The smaller the width of the carbon yarn, the higher the electrical resistance. The carbon net in the composites led to a decrease in internal bond strength. The carbon nets improved the flexural properties of the composites. Thickness swelling was significantly reduced by the use of carbon nets.

Superior catalytic effect of titania - porous carbon composite for the storage of hydrogen in MgH2 and lithium in a Li ion battery

A novel nanocomposite (0.2TiO2 + AC) with two promising applications is demonstrated, (i) as an additive for promoting hydrogen storage in magnesium hydride, (ii) as an active electrode material for hosting lithium in Li ion batteries (surface area of activated carbon (AC): 491 m2/g, pore volume: 0.252 cc/g, size of TiO2 particles: 20–30 nm). Transmission electron microscopy study provides evidence that well dispersed TiO2 nanoparticles are enclosed by amorphous carbon nets. A thermogravimetry-differential scanning calorimetry (TG-DSC) study proves that the nanocomposite is thermally stable up to ∼400 °C. Volumetric hydrogen storage tests and DSC studies further prove that a 3 wt% of 0.2TiO2+AC nanocomposite as additive not only lowers the dehydrogenation temperature of MgH2 over 100 °C but also maintains the performance consistency. Moreover, as a working electrode for Li ion battery, 0.2TiO2+AC offers a reversible capacity of 400 mAh/g at the charge/discharge rate of 0.1C and consistent stability up to 43 cycles with the capacity retention of 160 mAh/g at 0.4C. Such cost effective-high performance materials with applications in two promising areas of energy storage are highly desired for progressing towards sustainable energy development.

FILTRASI AIR SEDERHANA DENGAN METODE SLOW SAND FILTER UNTUK MEMPERBAIKI KUALITAS AIR SAMBUNGAN RUMAH MASYARAKAT SEKITAR SEI MERDEKA SAMBOJA KABUPATEN KUTAI KARTANEGARA

This research was conducted to help the community due to clean water problems in a simple and easy way. This research found a problem related to clean water in Sungai Merdeka Village, Samboja District, Kutai Kartanegara Regency, East Kalimantan Province. The problem experienced by the surrounding community is that the clean water that comes out of the house connection faucet cannot be used directly for cooking and drinking, but is only used for washing clothes, bathing and washing cutlery. People have consumed this water, but what happens is an uncomfortable feeling in the throat (inflammation) and when it use for bathing, it makes skin sometimes feels dry and tight. This is the reason to develop our research activities to find out how the condition of the water used by the community to fulfill their daily activities, to test the content of tap water in one of the residents' house. The efforts made to improve the quality of the Merdeka River community's tap water are by using Simple Filtration with the Slow Sand Filter principle, which is a filtering method that flows from the bottom up using several natural filter media without using chemicals. The media used include filter foam, silica sand, zeolite stone, activated carbon, palm fiber, and gauze nets. The pH value in residents' water faucets, which range from 4-6, that is not in requirements for clean water/drinking water issued by Permenkes no. 492 of 2010 which requires a pH value between 6.5 – 8.5. When compared to the pH value in the raw water source, namely the Merdeka River, it is even better, ranging from 5.6 to 6.4. The simple tool design was made, which namely Filtration with an upflow flow system (from bottom to top). The result is that after the residents' tap water is filtered through simple filtration, the air pH value becomes normal around 6.9 – 7.4. This means that the water meets the requirements set by the government according to the Minister of Health.

Structure and oxygen-sensitive properties of thin films of natural carbon

Thin film carbon nanomaterials are widely studied and used as functional, conductive, reflective, and sensor coatings. In this work, films of natural graphene-based carbon are studied as a sensitive material for a gas sensor operating close to room temperature. The structural features of the films were studied by scanning electron microscopy and Raman spectroscopy. It has been found that the deposition of natural carbon on substrates with a conductive coatings of indium oxide and of indium tin oxide allows to obtain a thin films, represented by homogeneous carbon nets, in the nodes of which are globular nano-sized particles. Microwave conductivity measurements were carried out using a λ/4 coaxial resonator based on a symmetric two-wire line. The results demonstrated that films on substrates with deposited indium oxide and indium tin oxide desorb oxygen from various structural levels of graphene-based carbon.

Facile and Scalable Synthesis of Si@void@C Embedded in Interconnected 3D Porous Carbon Architecture for High Performance Lithium‐Ion Batteries

AbstractSi‐based materials possess huge potential as an excellent anode material for Li‐ion batteries. However, how to realize scalable synthesis of Si‐based anode with a long cycling life and high‐performance is still a critical challenge. Here a water‐in‐oil microemulsion process followed by UV illumination, calcination, and hydrothermal method to produce yolk‐shell Si@void@C embedded in interconnected 3D porous carbon network architecture using silicon nanoparticles is reported. As a result, the sample Si@void@C/C‐2 electrode has achieved a reversible capacity of 1160 mA h g−1 at 0.2 A g−1 after 300 cycles and a stable long cycling life of 480 mA h g−1 at 1 A g−1 after 1000 cycles. A full battery with the synthesized anode shows a capacity of 128 mA h g−1 at 0.2 A g−1 as well as good cycling stability after 1100th cycles. Such excellent electrochemical performance is ascribed to its unique structure, the yolk‐shell void space, highly robust carbon shells and interconnected porous carbon nets that can improve the conductivity of the electrode, buffer the volume expansion, and also suppress Si nanoparticles stress variation. This water‐in oil system makes it possible for mass production of environmentally friendly synthesis of core–shell structure.

Parameter optimisation of a fibre reinforced polymer composite by RSM design matrix

Polymer composites fabricated from natural fibres gained popularity since they possess numerous advantages in automotives. But natural fibres suffer from lower strength which can be overcome through hybridisation with stronger synthetic fibres like carbon or glass. This work explores the potential reinforcement of fibres from palm leaf stalks for fabricating polymer composites. The fibres were pre-treated with glass fibres to form as fibre mats and hybridised with glass fibres prior to reinforcement. These mats were reinforced in the polyester resin matrix as different layers to form a hybrid composite. Experiments were done by varying the length of fibre, fibre volume and with different treatments using response surface methodology. Tensile strength was measured as response. The tensile strength was spotted maximum in 8% potassium permanganate (KMnO4) treated palm fibres with optimum fibre length 40 mm and volume fraction of 20%. The surface study on these composites through scanning electron microscope (SEM) examination was satisfactory. Hence this specimen combination was best suited and recommended to manufacture components like car bonnets, bumpers, etc.

Novel Rhenium Carbides at 200 GPa

Laser heating of rhenium in a diamond anvil cell to 3000±300 K at about 200 GPa results in formation of two previously unknown rhenium carbides, hexagonal WC‐type structured ReC and orthorhombic TiSi2‐type structured ReC2. The shortest C–C distances [1.758(3) Å at 219(5) GPa and 1.850(4) Å at 180(7) GPa] found in honeycomb‐like carbon nets in the structure of ReC2 are quite unusual. The Re–C solid solution formed at multimegabar pressure has the carbon content of ≈ 20 at%.

PROPOSALS FOR STRENGTHENING DAMAGED BRICK CONSTRUCTIONS

In the process of exploitation of a brick construction by virtue of different reasons there are cracks of different kind, however, after strengthening of constructions, they can be exploited further. The most effective and widespread method of strengthening of existent stone constructions is taking them in a hoop. Posts and piers with cracks, celled in a hoop, restore the bearing strength fully. Hoops can be next kinds: steel, reinforce-concrete, reinforced solution, from composition materials, like carbon fiber canvases, ribbons and nets, brick and armobrick. With the purpose of partial renewal of bearing strength of the damaged by the main cracks brick posts their reinforcement by reinforce-concrete hoop is offered. Re-enforcement is executed as an expanded metal, and piling of concrete solution was produced by guniting. The sequence of technological process of strengthening of brick constructions is fully expounded. It is shown that bearing strength of such complex construction is 1,4 times higher than primary construction of brick post, loading of cracking of such construction is 1,07 times higher. At this strengthening reinforce-concrete re-enforcement works only, and a brick kernel only performs the duty of filling, although loading is passed through a kernel.

Damage methodology approach on a composite panel based on a combination of Fringe Projection and 2D Digital Image Correlation

Abstract The recent improvement in accessibility to high speed digital cameras has enabled three dimensional (3D) vibration measurements employing full-field optical techniques. Moreover, there is a need to develop a cost-effective and non-destructive testing method to quantify the severity of damages arising from impacts and thus, enhance the service life. This effect is more interesting in composite structures since possible internal damage has low external manifestation. Those possible damages have been previously studied experimentally by using vibration testing. Namely, those analyses were focused on variations in the modal frequencies or, more recently, mode shapes variations employing punctual accelerometers or vibrometers. In this paper it is presented an alternative method to investigate the severity of damage on a composite structure and how the damage affects to its integrity through the analysis of the full field modal behaviour. In this case, instead of punctual measurements, displacement maps are analysed by employing a combination of FP + 2D-DIC during vibration experiments in an industrial component. In addition, to analyse possible mode shape changes, differences between damaged and undamaged specimens are studied by employing a recent methodology based on Adaptive Image Decomposition (AGMD) procedure. It will be demonstrated that AGMD Image decomposition procedure, which decompose the displacement field into shape descriptors, is capable to detect and quantify the differences between mode shapes. As an application example, the proposed approach has been evaluated on two large industrial components (car bonnets) made of short-fibre reinforced composite. Specifically, the evolution of normalized AGMD shape descriptors has been evaluated for three different components with different damage levels. Results demonstrate the potential of the presented approach making it possible to measure the severity of a structural damage by evaluating the mode shape based in the analysis of its shape descriptors.

Nitrogen-doped carbon nets with micro/mesoporous structures as electrodes for high-performance supercapacitors

Supercapacitors based on nitrogen-doped micro/mesoporous carbon nets exhibited excellent specific capacitance and energy density.

Squaroglitter: A 3,4-Connected Carbon Net.

Theoretical calculations are presented on a new hypothetical 3,4-connected carbon net (called squaroglitter) incorporating 1,4 cyclohexadiene units. The structure has tetragonal space group P4/mmm (No. 123) symmetry. The optimized geometry shows normal distances, except for some elongated bonds in the cyclobutane ring substructures in the network. Squaroglitter has an indirect bandgap of about 1.0 eV. The hypothetical lattice, whose density is close to graphite, is more stable than other 3,4-connected carbon nets. A relationship to a (4,4)nanotube is explored, as is a potential threading of the lattice with metal needles.

Sensor system for active car bonnets on test bench

In order to comply with the future requirements for enhanced pedestrian protection, the automotive industry will have to consider active protection systems that, for example, involve raising the bonnet in the event of an impact. Such systems will require sensors to detect an accident with a pedestrian. In this context, the Institute for Automotive Engineering (IFT) at Trier University of Applied Sciences has evaluated Kinotex sensors that were originally developed for use in space.

Pop-up car bonnets can reduce pedestrian deaths

Pop-up car bonnets can reduce pedestrian deaths

Coulomb gap and variable-range hopping in self-organized carbon networks

Carbon networks fabricated by means of a self-organized process, which is in the focus of our interest, represent disordered porous systems. The degree of disorder and, accordingly, the values of their electric conductivity extending from insulator to metal behavior change via heat treatment under vacuum conditions at process temperatures in the range from 600 to 1000 °C. Upon varying the ambient temperature from 4.2 to 295 K, four transport mechanisms can be observed. For carbon nets whose conductivity is far beyond the metal–insulator transition (MIT), the specific resistivity ρ depends on the temperature T as ρ(T)∝T−b exp([T0/T ]1/p). In the low-temperature range, a Coulomb gap in the density of states located near the Fermi energy level occurs, which means that the characteristic value of the exponent is p=2. At high temperatures, the pre-exponential part ρ(T)∝T−b dominates. In the intermediate temperature range, we disclose Mott’s hopping law with p=3. However, the specific resistivity of the carbon networks subject close to the MIT follows the power law ρ(T)∝T−b with 0≲b≲3 at low temperatures. In the high-temperature range, the specific resistivity is characterized by ρ(T)∝exp(−[T/T1]c−1), where the values for c vary from 1.3 to 1.5. The above four charge transport mechanisms can be explained by the tails in the density of localized states pulled out of the conduction and valence band, as a consequence of disorder and, particularly, by some overlap between these tails.

Thermal Conditions Favoring Buckytube Growth on the Anode

ABSTRACTThe most widespread methoid for buckytube synthesis is by arc discharge in an inert gas ambient. At arc discharge the major kind of charge carriers are the electrons generated from the cathode by thermal emission. For this reason up until now the deposit was always obtained on the cathode. By supplementary electrode heating and cooling we studied the effects of the anode-cathode temperature difference and found that it plays a major role in defining the quality and quantity of the deposit obtained. Given appropriate heat-up or cool-down of the electrodes, a state can be reached such that the temperature at the cathode is higher than the temperature at the anode. A deposit was obtained on the anode, observed by a TEM. In our view employing this method yields the most favorable conditions for buckytube growth. Our results show that except buckytubes with a high ratio of their length with respect to their width, a multitude of small size polyhedral carbon systems closed in by spatial carbon nets and thin flat interfering carbon plates were also obtained. When using electrodes of different cross-section, with the deposition of an ever thicker deposit on the anode, its temperature regime changes. The lower initial temperature at the anode begins to grow steadily with time tending towards the temperature at the cathode. Thus, buckytube growth proceeds at the lowest possible rate, at a small temperature difference between the vapor source and growing structure. In our view employing this method yields the most favorable conditions for buckytube growth.

ChemInform Abstract: Organic Ferromagnets. New Results.

Abstract Theoretic generalization of ferromagnetic ordering in low and three-dimensional organic substances has been achieved. The conception of ferromagnetic exchange in boron or nitrogen substituted 2-dimensional carbon nets has got further development. Fundamentally new result has been obtained on the possibility of the ferromagnetic interaction of spins separated by sp 3 -centre. Basing upon this theoretic approach a number of three-dimensional carbon structures has been forwarded. The estimated theoretic magnetization of substances with such structures reaches 230 G g −I , which is somewhat above the record magnetization of α -Fe (2I5G-g −I ). These structures may be considered as intermediate graphite-diamond structures (IGD-structures). The organic materials with saturation magnetization around 200 G.g −I have been found in the products of controlled pirolysis of polyacrilonitryl. Curie temperature of this material is 480°C.

Organic ferromagnets. New results

Theoretic generalization of ferromagnetic ordering in low and three-dimensional organic substances has been achieved. The conception of ferromagnetic exchange in boron or nitrogen substituted 2-dimensional carbon nets has got further development. Fundamentally new result has been obtained on the possibility of the ferromagnetic interaction of spins separated by sp 3-centre. Basing upon this theoretic approach a number of three-dimensional carbon structures has been forwarded. The estimated theoretic magnetization of substances with such structures reaches 230 G g −I, which is somewhat above the record magnetization of α -Fe (2I5G-g −I). These structures may be considered as intermediate graphite-diamond structures (IGD-structures). The organic materials with saturation magnetization around 200 G.g −I have been found in the products of controlled pirolysis of polyacrilonitryl. Curie temperature of this material is 480°C.

Carbon network building blocks: triethynyl methanol and derivatives

Triethynyl methanol, a key intermediate in the synthesis of carbon nets, and some derivatives have been synthesized by oxidation of the corresponding secondary alcohol and reaction with lithio(trimethylsilyl)acetylene.

3,4-Connected carbon nets: through-space and through-bond interactions in the solid state

A theoretical study of a series of “honeycombed” or ”layered” 3,4-connected nets is presented. The most significant feature of this series of nets is that they have infinite stacks of carbon-carbon double bonds in close contact with each other. Two of these nets have structures that not only contain stacks of 3-connected centers but also have infinite 1-dimensional polymeric units related to cis-polyacetylene. We employ tight-binding band structure calculations on selected examples of these nets to determine their electronic properties. The consequences of a stacked structure are analyzed by calculating the band structure of infinite layers (stacks) of ethylenes. Some of these carbon nets may be metallic. We also show that through-space and through-bond (hyperconjugative) interactions are important in the solid state, but the overall effect of these interactions varies according to the area of k-space that is being sampled. Pursuing our continuing interest in alternative structures of diamond and graphite,’ we decided to study a series of 3,4-connected nets. There are a number of reasons for examining these nets: first, they have an intermediate valency between graphite (3-connected) and diamond (4-connected); second, the density of the nets we will be studying here is intermediate (-3.0 g/cm3) between that of diamond (3.51 g/cm3) and graphite (2.27 g / ~ m ~ ) ; ~ and third, these nets are interesting because they have close intrastack distances (2.3 to 2.8 A) thereby allowing for greater (especially T ) band dispersions (this may make these nets metallic). Before proceeding to a discussion of the electronic properties of these nets we would like to review briefly the current status of the allotropy of carbon. The structurally well-characterized allotropes of carbon are restricted to only two main types: diamond (cubic and hexagonal) and graphite (hexagonal and rh~mbohedra l ) .~ In cubic (1) and hexagonal diamond (2) each carbon atom is tetrahedrally surrounded by four other carbon atoms at a distance of 1.545 A. The structural differences between these two diamond forms can be envisioned in this way: 1 can be imagined to consist of an infinite network of adamantyl moieties, all chair cyclohexane rings, whereas in 2 there are some chair and some boat six-membered T Cornell University. *The Polytechnic. 0002-7863/87/ 1509-6742$01.50/0 rings. Both hexagonal (3) and rhombohedral (4) graphite contain hexagonal carbon layers linked by van der Waals forces. The difference, though, between these two forms lies in the stacking of these sheets. In 3 every third layer repeats (ABAB ...) with the first and second layers displaced away from each other in such a way that one-half of the atoms in each layer are above and below the center of the hexagon in the neighboring layer. 4, on the other hand, has every fourth layer repeating to give an ABCABC ... stacking pattern. There is some evidence for other carbon allotrope^.^ The best studied of these is karbin, sometimes called ~ h a o i t e . ~ . ~ Its structure is thought to contain carbon in alkyne or cumulene needles, 5. Though there has been much work on karbin, our opinion is that (1) Hoffmann, R.; Hughbanks, T.; Kertesz, M.; Bird, P. H. J . Am. Chem. SOC. 1983, 105, 4831. Hoffmann, R.; Eisenstein, 0.; Balaban, A. T. Proc. Nutl. Acad. Sci. U.S.A. 1980, 7 7 , 5588. Balaban, A. T.; Rentia, C. C.; Ciupitu, E. Rev. Roum. Chim. 1968, 13, 231; erratum: Ibid. 1968, 13, 1233. (2) These are theoretical densities calculated from idealized geometries and should be considered as an upper limit to the experimental densities. (3) Donohue, J. The Structure ofthe Elements; Wiley: New York, 1974. (4) S,e the following recent review of experimental and theoretical work: Stankevich, I . V.; Nikerov, M. V.; Bochvar, D. A. Usp. Khim. 1984,53, 1101; Russ. Chem. Reu. 1984, 53, 640. (5) For a review on karbin see: Mel’nichenko, V . M.; Sladkov, A. M.; Nikulin, Yu. N . Usp. Khim. 1982, 51 , 736; Russ. Chem. Reu. 1982, 51, 421. (6) Whittaker, A. G. Science 1978, 200, 763.