Mechanical Properties of Graphene Oxide-Copper Composites

Due to their characteristics, sintered Cu-C composites are materials used in electrical equipment. These characteristics include high electrical conductivity, thermal conductivity and excellent resistance to abrasion. Currently, graphite nanopowder is used successfully as a carbon material. Metal-graphite, which is created on its basis, exists in different proportions of graphite to metal. A larger graphite content has a positive effect on smaller wear of commutators and rings. In contrast, a material with a higher copper content is used at high current densities. An example of such machines is a DC motor starter characterized by low voltage and large current. Tribological properties of Cu-C composites depend on the form of carbon they include. Owing to the capability to manufacture graphene, it has become possible to produce composites with its content. The present study tested the effect of a graphene oxide content on tribological properties in contact with steel. Tests were conducted on a ball-on-disk apparatus in conditions of dry friction. Microscopic observation was performed on the Hitachi SU70 field emission electron microscope. EDS analyses were performed using the Thermo Scientific X-ray Microanalysis system. Disk wear and surface geometrical structure parameters (SGP) of the samples after tribological tests were determined on the basis of measurements made on the Talysurf 3D contact profilometer from Taylor Hobson

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Impact of Plastic Blends on the Gaseous Product Composition from the Co-Pyrolysis Process

The co-pyrolysis of various biomasses mixed with two types of plastic waste was investigated in this study. Mixture M1 consisted of 30% m/m styrene–butadiene rubber (SBR), 40% m/m polyethylene terephthalate (PET), and 30% m/m polypropylene (PP). M2 consisted of 40% m/m PET, 30% m/m PP, and 30% m/m acrylonitrile–butadiene–styrene copolymer (ABS). The SBR, ABS, and PP used in this study were from the automotive industry, while the PET originated from scrap bottles. Co-pyrolysis was performed using wood biomass, agricultural biomass, and furniture trash. Thermal treatment was performed on samples from room temperature to 400 or 600 °C at a heating rate of 10 °C/min under N2 at a flow rate of 3 dm3/min. Based on the findings of the experiments, an acceptable temperature was found for the fixed-bed pyrolysis of biomass–plastic mixtures with varying ratios, and the raw materials were pyrolyzed under the same conditions. The composition of the derived gaseous fraction was investigated. The co-pyrolysis studies and variance analysis revealed that combining biomass with plastic materials had a good influence on the gaseous fraction, particularly in the presence of 6.6–7.5% v/v hydrogen and a lower heating value of 15.11 MJ/m3. This type of gaseous product has great potential for use as a replacement for coke oven gas in metallurgy and other applications

Comparison of Gas Sensing Properties of Reduced Graphene Oxide Obtained by Two Different Methods

In this study, the sensitivity of reduced graphene oxide structures (rGO) to the action of selected gases (especially hydrogen, but also nitrogen dioxide and ammonia) was examined. Two sensing structures, based on rGO structures, obtained by different methods of oxidation (the modified Hummers, and the modified Tour’s method respectively), were investigated. We show here that the method used for the oxidation of rGO influences the sensitivity of the sensing structure during contact with various gaseous atmospheres. We performed our experiments in the atmosphere, containing hydrogen in a concentration range from 0 to 4% in nitrogen or synthetic air, both in dry and wet conditions. The temperature range was from 50 °C to 190 °C. Finally, we checked how the resistance of the samples changes when the other gases (NO2, NH3) appear in tested gas mixtures. The gas investigations were supplemented by the characterization of rGOs materials using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 sorption method

Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy Statistical Analysis

In this paper, various graphite oxide (GO) and reduced graphene oxide (rGO) preparation methods are analyzed. The obtained materials differed in their properties, including (among others) their oxygen contents. The chemical and structural properties of graphite, graphite oxides, and reduced graphene oxides were previously investigated using Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). In this paper, hierarchical clustering analysis (HCA) and analysis of variance (ANOVA) were used to trace the directions of changes of the selected parameters relative to a preparation method of such oxides. We showed that the oxidation methods affected the physicochemical properties of the final products. The aim of the research was the statistical analysis of the selected properties in order to use this information to design graphene oxide materials with properties relevant for specific applications (i.e., in gas sensors)

Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy

In this paper, the influences of the graphite precursor and the oxidation method on the resulting reduced graphene oxide (especially its composition and morphology) are shown. Three types of graphite were used to prepare samples for analysis, and each of the precursors was oxidized by two different methods (all samples were reduced by the same method of thermal reduction). Each obtained graphite oxide and reduced graphene oxide was analysed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (RS)

Oxidative Liquefaction, an Approach for Complex Plastic Waste Stream Conversion into Valuable Oxygenated Chemicals

Various waste streams including municipal solid waste (MSW), polymer waste from personal protective equipment (PPE) used in medical fields, and composite waste from wind turbine blades (WTBs) demand modern waste management and recycling approaches. Ultimate and proximate analysis of mentioned samples revealed a higher content of carbon—28.2 ± 8.0, 80.1 ± 2.3, and 50.3 ± 2.3, respectively—exhibiting sufficient potential to be converted into secondary carbon-based compounds. For this purpose, oxidative liquefaction of selected waste materials was carried out following a detailed experimental plan, a centred composite design for WTBs, and a central composite face-centred plan for MSW and PPEs. Temperature, pressure, oxidant concentration, reaction time, and waste-to-liquid ratio were the parameters of key interest, and their values were tested at a range of 200–350 °C, 20–40 bar, 15–60%, 30–90 min, and 3–25%, respectively, depending upon the type of waste. As a result, total polymer degradation (TPD) was recorded for three types of waste and the results were satisfactory, encouraging the decomposition of primary waste in liquid oxygenated chemical compounds (OCCs). Gas Chromatography with Flame Ionisation Detection (GC-FID) helped us quantify the number of OCCs for each waste sample. Energy consumption during the process was also recorded and optimisation of the experimental plan based on maximum TPD and OCCs yields against the minimum energy consumption was performed to make the process tech-economic

A Comparative Analysis of Waste Biomass Pyrolysis in Py-GC-MS and Fixed-Bed Reactors

Pyrolysis is one of the most popular methods for the thermal conversion of biomass-derived materials, which can be applied to produce valuable products such as biochar, bio-oil, and pyrolysis gas. However, this does not change the need for more precise data on the products obtained from such processes under different conditions, using different types of reactors or types of biomass material. Pyrolysis products can have a high energy value and have been extensively studied. In the presented research, three potential energy feedstocks from waste biomass, wheat cereal straw (CS), tobacco waste (TW), and furniture waste (FW) were comprehensively evaluated in terms of product yields, as well as the chemical composition of the volatile products of the pyrolysis process using the pyrolysis–gas chromatography–mass spectrometry technique and the chemical distribution of the products obtained under fixed-bed pyrolysis conditions. The obtained results were compared to data from the literature, which provided thorough information on the pyrolysis of biomass materials in diverse systems. The research identified the primary elements of the liquid fraction, such as N-compounds, furans, phenols, benzene, PAHs, aldehyde-ketone-alcohol, and organic acids, which were the main constituents of the liquid fraction, and the concentration of non-condensable components of gaseous products. The research discussed in this article provides a comprehensive approach to the thermal conversion of biomass materials, which, depending on their origin, processing conditions, and methodologies, can be utilised for more than only energy production

Studies of physicochemical properties of graphite oxide and thermally exfoliated/reduced graphene oxide

The aim of the experimental research studies was to determine some electrical properties of graphite oxide and thermally exfoliated/reduced graphene oxide. The authors tried to interpret the obtained physicochemical results. For that purpose, both resistance measurements and investigation studies were carried out in order to characterize the samples. The resistance was measured at various temperatures in the course of composition changes of gas atmospheres (which surround the samples). The studies were also supported by such methods as: scanning electron microscopy (SEM), Raman spectroscopy (RS), atomic force microscopy (AFM) and thermogravimetry (TG). Moreover, during the experiments also the elemental analyses (EA) of the tested samples (graphite oxide and thermally exfoliated/reduced graphene oxide) were performed