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EN
This work is the continuation and refinement of already published communications based on PET/EG nanocomposites prepared by in situ polymerization1, 2. In this study, nanocomposites based on poly(ethylene terephthalate) with expanded graphite were compared to those with functionalized graphite sheets (GO). The results suggest that the degree of dispersion of nanoparticles in the PET matrix has important effect on the structure and physical properties of the nanocomposites. The existence of graphene sheets nanoparticles enhances the crystallization rate of PET. It has been confirmed that in situ polymerization is the effective method for preparation nanocomposites which can avoid the agglomeration of nanoparticles in polymer matrices and improve the interfacial interaction between nanofiller and polymer matrix. The obtained results have shown also that due to the presence of functional groups on GO surface the interactions with PET matrix can be stronger than in the case of exfoliated graphene (EG) and matrix.
EN
The aim of the work presented in the article was to clarify controversial comments about anti-corrosion and mechanical properties of graphene coatings, deposited on copper substrates. It was designed special experimental cycle comprising: preparation of graphene forms and copper, the observation of layers Cu / GO (rGO) after the thermal reduction processes and oxidative test in air at 150°C temperature and 350 h in time. The resulting coatings and graphene layers were subjected to tribological test for hardness. The observed differences in the continuity of the coverage copper surface by graphene forms, allowed to understand the macroscopic effect of increased hardness and wear resistance layers rGO/Cu.
EN
The paper presents the results of studies on the preparation and properties of composite granules produced by phase inversion from cellulose (CEL) solutions in 1-ethyl-3-methylimidazole acetate (EMIMAc), containing nano-addition in the form of graphene oxide (GO) in N,N-dimethylformamide (DMF). Water absorption and sorption of such compounds as FeCl3, methylene blue (MB) and bovine serum albumin (BSA) were studied. In addition, attempts were made to investigate the sorption properties of the obtained cellulose granules in terms of metals removal from galvanizing wastewater. Among the many components, iron and lead were found to have the highest concentration (~ 1 mg Fe/dm3; ~2 mg Pb/dm3) in the tested wastewater sample. The qualitative and quantitative composition of the wastewater was examined by UV-Vis spectrophotometry. The studies show that doping of cellulose with Graphene oxide clearly affects the physical properties of this biopolymer. GO improves the water absorption of CEL/GO composite cellulose granules only in the concentration above 0.05% w/w. For a concentration of 0.1% w/w of GO in cellulose, water absorption is increased by ~108% compared to pure cellulose granules. In addition, the use of dry and wet granules in the study changes their sorption properties with respect to all tested substances. Studies on test solutions have shown that the sorption of cellulose granules decreases with increasing molar mass of test compounds, in the following order: FeCl3, methylene blue (MB) and bovine albumin (BSA). This means that the cellulose granules obtained in the experiment are made up of small micropores, which makes the diffusion of compounds of high molecular weight difficult. The best sorption results were obtained for ferric ions and amounted to 66–72% for FeCl3 solution, and ~92% for the wastewater that was sorbed on pure cellulose granules.
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Content available remote Graphene as a material for solar cells applications
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EN
Graphene is a two-dimensional material with honeycomb structure. Its unique mechanical, physical electrical and optical properties makes it an important industrially and economically material in the coming years. One of the application areas for graphene is the photovoltaic industry. Studies have shown that doped graphene can change one absorbed photon of a few electrons, which in practice means an increase in efficiency of solar panels. In addition, graphene has a low coefficient of light absorption 2.3% which indicates that is an almost completely transparent material. In fact, it means that solar cells based on graphene can significantly expand the absorbed spectrum wavelengths of electromagnetic radiation. Graphene additionally is a material with a very high tensile strength so it can be successfully used on the silicon, flexible and organic substrates as well. So far, significant effort has been devoted to using graphene for improving the overall performance of photovoltaic devices. It has been reported that graphene can play diverse, but positive roles such as an electrode, an active layer, an interfacial layer and an electron acceptor in photovoltaic cells. Research on solar cells containing in its structure graphene however, are still at laboratory scale. This is due to both lack the ability to produce large-sized graphene and reproducibility of its parameters.
EN
The paper presents the results of microbiological tests of composite membranes made of cellulose (CEL) with graphene oxide (GO) admixture. At the beginning, the antibacterial properties of the GO in aqueous solutions of various concentrations (0.001; 0.01; 0.1% w/w) were studied, and the obtained results allowed to use GO as an additive to cellulose membranes. The solution used to prepare the membranes was a 5% cellulose solution (CEL) in 1-ethyl-3-methylimidazolium acetate (EMIMAc), into which various amounts of graphene oxide (GO) dispersed in N,N-dimethylformamide (DMF) were added (0.5÷28.6% of GO). From this solution, composite membranes were formed using phase inversion method. It was observed that the GO addition influences the process of membrane formation and their physicochemical properties. The obtained membranes were subjected to microbiological tests using the Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcuc aureus) and fungi (Candida albicans). It was observed that the GO addition to the cellulose membrane (GO/CEL) inhibited the growth of bacteria and fungi, and the biological activity as dependent on the type of living organism and the size of GO particles.
EN
The objective of the work was to investigate the possibility of application of carbon and bentonite nanoparticles in carboxylated acrylonitrile-butadiene rubber (XNBR) and the related effects of the nanofi llers on the structure, as well as mechanical and barrier properties, of the resulting composites. The composites were designed for use in protective clothing and gloves. XNBR compounds were modifi ed with 2 phr of graphene fl akes, graphene oxide, or modifi ed bentonite, and crosslinked with sulfur-accelerator system. Rubber compounds were prepared using a conventional method with a laboratory rolling mill. The composites were studied in terms of structure (WAXS), surface morphology (AFM), the presence of functional groups (ATR-FTIR) barrier properties against chemical substances (mineral oil) and swelling properties, as well as mechanical properties (abrasion resistance and tensile strength). The composites were characterized by very high resistance to oil permeation (breakthrough time >480 min). The type of nanofi ller added to the XNBR blend in the amount of 2 phr did not signifi cantly affect mechanical parameters.
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Content available remote Preparation of rGO/ZnO photoanodes and their DSSCs performance
88%
EN
In this study, we report a mild and controllable preparation method for graphene oxide (GO) and ZnO ultrafine powder, respectively. On this basis, reduced graphene oxide (rGO)/ZnO composite powder for the photoanodes of dye-sensitized solar cells (DSSCs) was synthesized by chemical reduction method. Phase composition, microstructure, chemical structure, conductivity, and specific surface area were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), Raman, and Brunauer-Emmett-Teller (BET) method, respectively. Photoelectric performance of DSSCs was studied by the current density-voltage (J-V), electrochemical impedance spectra (EIS) photoelectric test system. As rGO possesses higher adsorption capacity and excellent conductivity, hence it may effectively promote separation of electrons and holes, transmission ability of electrons and holes, and utilization of the light. By contrast, the as-synthesized zinc oxide (ZnO) may increase adsorption capacity of dye molecules, so photoelectric conversion efficiency (PCE) of the solar cells is increased by means of synergistic effects. When adding rGO in the rGO/ZnO composite powder at 1.25 wt%, PCE reaches to 6.27%, an increase of 20.6% more than that of pure ZnO as the photoanode.
EN
The paper studies the effect of incorporating graphene oxide (GO) without surface functionalization on a commercial epoxy resin. GO was dispersed in a commercial epoxy resin at concentrations of 0 wt.%, 0.1 wt.%, 0.5 wt.%, 1 wt.%, and 3 wt.%. The resultant materials were deposited on carbon steel substrates, followed by the use of a 5 wt.% aqueous NaCl electrolyte, to evaluate the effectiveness of their anticorrosive coating function. Scanning electron microscopy (SEM) analysis showed that the GO was homogenously dispersed in the polymer matrix, resulting in flat and smooth surfaces. The X-ray diffraction (XRD) results showed that although GO was highly dispersed in the polymer matrix, multilayer graphene was also obtained after curing. The anticorrosive properties were evaluated by electrochemical impedance spectroscopy (EIS) at various exposure periods. Analysis of the prepared samples indicated that the best anticorrosion performance among them was available with the 0.5 wt.% GO coating. The obtained results indicate that GO–polymer matrix composites provide improved corrosion protection properties even after 500 h exposure to the NaCl solution.
EN
Combinations of biopolymers with nanostructured carbon materials have been the subject of interest of many scientists in recent years. Particularly significant are nanocomposites made of chitosan, which is a linear aminopolysaccharide obtained in the process of deacetylation of chitin, and graphene oxide (GO). These systems, due to the atypical properties of both components such as non-toxicity, biocompatibility with human tissues and organs as well as bacteriostaticity, are characterised by a wide range of biomedical applications. They may be used in emergency medicine as dressing materials which accelerate wound healing, as well as carriers of drugs/genes and biological macromolecules, for example proteins, peptides and nucleic acids. In addition, CS-GO systems can potentially be used in regenerative medicine as scaffolds for cell culture. For this reason, the current publication presents the possibilities of the application of chitosan–graphene oxide nanocomposites in medicine considering the characteristics of the system components.
EN
Purpose: Nanocomposite materials, comprising of polymer matrices and nano-sized reinforcements, exhibit significantly enhanced mechanical and functional properties at extremely low filler loading. In recent years, graphene oxide (GO) has emerged as a new class of low cost nano-filler with high mechanical strength and stiffness, and alterable electrical properties. For nano-fillers with layered structure like GO, complete exfoliation and uniform dispersion of filler in the polymer matrices is essential to enhance the matrix-filler interaction and in turn the mechanical and/or functional property improvement. Conventional nanocomposite manufacturing methods including in-situ polymerisation and solvent processing encounter the problem of agglomeration of GO films. Additionally, its low bulk density presents difficulties in handling, and the energy requirement for mechanical mixing and extrusion processes is very high. In this work, we report manufacturing of poly(methyl methacrylate)-graphene oxide (PMMA-GO) nano-fibre mat using relatively novel approach of employing electrospinning technique. The manufactured electrospun core was inserted between plain polymer layers to prepare a robust and easy to handle sandwich film. Morphology and structure of the PMMA-GO nano-fibre cores was evaluated with scanning and transmission electron microscopy and X-ray diffractometry. The manufactured nano-fibre mat samples exhibited uniform diameter and dispersion. The functional parameters including thermal stability and gas barrier were evaluated with differential scanning calorimetry and oxygen permeation testing, and these functional properties were observed to be superior to that of monolithic polymer counterparts.
EN
This paper presents a comparative study on which type of platelets nanofiller, organic or inorganic, will affect the properties of thermoplastic elastomer matrix in the stronger manner. Therefore, poly(trimethylene terephthalate-block-poly(tetramethylene oxide) copolymer (PTT-PTMO) based nanocomposites with 0.5 wt.% of clay (MMT), graphene nanoplatelets (GNP) and graphene oxide (GO) have been prepared by in situ polymerization. The structure of the nanocomposites was characterized by transmission electron microscopy (TEM) in order to present good dispersion without large aggregates. It was indicated that PTT-PTMO/GNP composite shows the highest crystallization temperature. Unlike the addition of GNP and GO, the introduction of MMT does not have great effect on the glass transition temperature of PTMO-rich soft phase. An addition of all three types of nanoplatelets in the nanocomposites caused the enhancement in tensile modulus and yield stress. Additionally, the cyclic tensile tests showed that prepared nanocomposites have values of permanent set slightly higher than neat PTT-PTMO.
EN
This article describes a method for producing polymeric membranes by adding carbon nanostructures in the form of graphene oxide (GO). The reference membrane (having typical composition) was formed via phase inversion, using polyvinylidene fluoride (PVDF) dissolved in dimethylacetamide (DMAC). The polymeric matrix was additionally enriched with a plasticizer, i.e. polyethylene glycol (PEG). Afterwards, graphene oxide ultrasonically dispersed in dimethylacetamide was added to basic matrix. The membranes were further compared with one another by measuring their contact angle and hydrodynamics. The results were compared with the literature reports. The transport properties of the membranes were assessed with experimental ultrafiltration equipment (KOCH Membrane System). Also, their permeate flux and mass transfer resistance were determined.
15
Content available Metody syntez i badania właściwości grafenu
75%
PL
Grafen i jego pochodne są materiałami o unikalnych właściwościach biochemicznych, elektrycznych, optycznych i mechanicznych, co wzbudza zainteresowanie w wielu ośrodkach badawczych. Z tego powodu, na podstawie dostępnej literatury, podjęliśmy próbę zestawienia i interpretacji wyników badań uprzednio wymienionych materiałów otrzymanych różnymi metodami. Analizując wyniki badań różnych materiałów grafenopodobnych, można przypuszczać, że najbardziej ekonomiczną metodą otrzymywania grafenu jest zmodyfikowana metoda Hummersa. Najlepszymi technikami pomiarowymi są spektroskopia Ramana i rentgenowska spektroskopia fotoelektronów. Obydwie techniki umożliwiają ocenę składu chemicznego badanych próbek oraz stopnia ich zdefektowania. W pracy przedstawiono również niektóre z licznych zastosowań tych materiałów oraz wnioski.
EN
Graphene and its derivatives are the materials with unique biochemical, electric, optical and mechanical properties, which has aroused interest in many research centres. Therefore, on the basis of the accessible literature, we attempt to collate and interpret the results of the aforesaid materials obtained by different methods. Analysing the results for the different graphene-like materials one can suppose, that the most economical method of the graphene synthesis is the modified Hummers’ method. The most useful testing techniques are the Raman spectroscopy and the X-ray photoelectron spectroscopy. Both techniques enable the estimation of the chemical composition and the presence of defect structure in the materials. Some of the many applications of the materials and conclusions are also presented in our review.
16
75%
EN
Purpose: The aim of the paper is to fabricate semi-transparent graphene oxide counter electrodes for dye-sensitized solar cells. Design/methodology/approach: A thermal reduction is applied to decreased the amount of surface oxygen functionalities on graphene sheets. For this purpose thermal treatments in oven in 250°C and 500°C were used. Graphene oxide materials were mixed with PEDOT:PSS and then deposited on FTO glass by spin coating method. PEDOT:PSS was added to graphene oxide to increase conductivity and enhance film forming ability. Findings: Ultraviolet-visible spectroscopy measurement was carried out to monitor the degree of oxidation for the graphene samples. It has been found that annealing of graphene oxide counter electrodes under inert atmospheres enable a better ordering of graphene oxide films and also cause losing an oxygen functional groups, that makes layers become denser and smother, with a lower surface roughness, and thus less transparent. Research limitations/implications: It has been found that due to development of the technology of dye-sensitized solar cells with graphene oxide counter electrode, it is possible to lowering a production costs by replacing a costly platinum. It is advisable to take into account in the further experiments application of counter electrode on different kinds of substrates in the selected process parameters, and research for using them in DSSC cells mass production. Practical implications: DSSC cells are an interesting alternative to silicon solar cells. Presented in this paper results showed possibilities of modify dye-sensitized solar cells by replacing costly platinum. Originality/value: It was shown that dye-sensitized solar cells with graphene oxide counter electrode can be used in building integrated photovoltaic.
PL
Celem tej publikacji jest przedstawienie wyników badań bazy olejowej SN-650 z różnymi stężeniami tlenku grafenu (GO), zredukowanego tlenku grafenu (rGO) wyprodukowanych przez Instytut Technologii Materiałów Elektronicznych w Warszawie oraz heksagonalnego azotku boru (h-BN) wytwarzanego według technologii opracowanej w Wojskowej Akademii Technicznej. W pierwszej części pracy przedstawiono podstawowe wiadomości na temat grafenu i tlenku grafenu oraz możliwości ich zastosowania, w szczególności w dziedzinie tribologii. W drugiej części publikacji zaprezentowano wyniki badań właściwości smarnościowych próbek z dodatkiem 0,05%, 0,1%, 0,5%, 1% i 2% masy tlenku grafenu, zredukowanego tlenku grafenu oraz heksagonalnego azotku boru. Pomiary zrealizowano przy wykorzystaniu uniwersalnego nanomikrotestera UNMT oraz aparatu czterokulowego T-02, w Zakładzie Tribologii, Inżynierii Powierzchni i Logistyki Płynów Eksploatacyjnych (od 1.10.2019 r. Zakład Materiałów Pędnych i Smarów) Wydziału Mechanicznego (od 1.10.2019 r. Wydział Inżynierii Mechanicznej) Wojskowej Akademii Technicznej. Otrzymane wyniki wykazały korzystny wpływ wprowadzania do bazy olejowej SN-650 dodatków w postaci tlenku grafenu lub heksagonalnego azotku boru na właściwości tribologiczne oleju.
EN
The aim of this publication is to present the results of studies on the SN-650 oil base with various concentrations of graphene oxide (GO), reduced graphene oxide (rGO) produced by the Institute of Electronic Materials Technology in Warsaw and hexagonal boron nitride (h-BN) produced according to the technology developed at the Military University of Technology. The first part of the publication presents basic information about graphene oxide and the possibilities of its use, in particular in the field of tribology. The second part of the publication presents the results of tests of lubricity properties of the samples with the addition of 0.05%, 0.1%, 0.5%, 1% and 2% of graphene oxide, reduced graphene oxide or hexagonal boron nitride. The measurements were carried out using the UNMT universal nano/microtester tester and the T-02 four-ball device, at the Department of Tribology, Surface Engineering and Logistics of Service Fluids, which is a part of the Institute of Mechanical Vehicles and Transport of the Mechanical Faculty of the Military University of Technology. The obtained results have demonstrated the beneficial effect of introducing additions in the form of graphene oxide or hexagonal boron nitride onto the tribological properties of the oil base.
EN
Biomimetic mineralized composite scaffolds are widely used as natural bone substitute materials in tissue engineering by inducing and assembling bonelike apatite. In this study, the single lamellar structure of graphene oxide (GO) powder was prepared via an improved Hummers’ method. Methods: To better mimic natural bone, the collagen (COL)/Nano-hydroxyapatite (nHA)/graphene oxide (GO) composite material was prepared by simulated body fluid (SBF) method using COL/GO as a matrix template. Hydroxyapatite (HA) with calcium ion deficiency was achieved via biomimetic mineralization, and it had properties closer to those of natural bone than pure HA has. Results: The mineralized COL/nHA/GO composites exhibited loose porous structures, and the connectivity of the holes was good and thus beneficial to the exchange of nutrients and excreted metabolites. Conculsions: Antibacterial and MTT experiment confirmed that the COL/nHA/GO composite material had excellent antibacterial property and biocompatibility. Hence, these results strongly suggested the mineralized COL/nHA/GO composite is a good candidate biomaterial to be applied in bone tissue engineering.
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tom Vol. 23, no. 3
art. no. e202, 2023
EN
Accurately predicting the 28-day compressive strength (CS) of carbon nanotubes-reinforced cement composites (CNTRCCs) and graphene oxide-reinforced cement composites (GORCCs) is crucial for accelerating their potential application in civil engineering. However, traditional experimental and theoretical modeling methods suffer from problems, including time-consuming, costly, and inefficient. Moreover, it is also challenging to consider the effects of multiple coupling factors. In this work, a multimodal machine learning (ML) approach is proposed as the first attempt to explore the complex relationships between the CS of hybrid system containing both CNTRCCs and GORCCs. The proposed multimodal ML shows great potential in estimating the nanomaterials-reinforced cement composites with a coefficient of determination (R2) of 0.96, surpassing the single-modal ML approaches. The results demonstrate the effectiveness of the developed model in accurately predicting the 28-day CS of hybrid system containing both CNTRCCs and GORCCs. Shapley additive explanations (SHAP) analysis illustrates that the optimal concentration of CNT is approximately 0.5 wt%, and preferred length of CNT and sheet size of GO are within a range of 20–30 μm and below 10 μm, respectively. Additionally, the enhancement effect of a single-layer GO is better than its multilayer counterparts.
EN
The proposed work is about the investigation of nano-textured tool insert with magnetor-heological-based graphene coating process. The comparative study on nano-textured car-bide insert with unpolished one for turning duplex stainless steel (S31803/2205) is made by conducting number of experiments with Box–Behnken design using response surface methodology. An array of sensor based on the conductive element of chromel and alumel core integrated through DC magnetron sputtering on the rake surface of the tool insert. The performance of the proposed sensor was evaluated from the obtained thermo-electromotive force on tool chip contact interference and the temperature measurements taken at the contours of multiple points with respect to the tool wear. Results obtained clarify that with the rise in cutting tool temperature leads to the rise in tool wear based on the adhesion and abrasion. It has been found that the graphene coated tool inserts provides high wearable resistances with flank wear of 0.298 mm at 21st pass. The cutting tool temperature is found to spread uniformly with a value of 202 8C for graphene coated inserts for cutting speed of 55 m/min. Microstructural images taken proved that the formation of cementite and carbides with inter metallic compounds (IMCs) produced during the tool chip interface leads to the strengthening of tool tip in reducing the tool-wear. Also the occurrence of ultrafine grain boundaries on the tool tip occurs increasing the formation of covalent bonds in providing the robust resistance against tool wears.
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