Fluorocarbon Compounds Research Articles

Effect of outdoor ageing on pyrolytic characteristics and kinetics of different organic components in waste photovoltaic panels

Pyrolysis is a potential approach for volume reduction and utilization of organic components in waste photovoltaic panels. During a usage period of 20–25 years, the physical and chemical properties of photovoltaic panels might undergo ageing and deterioration, thereby affecting their thermal decomposition characteristics. The characteristics of samples before and after ageing were studied using Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analyzer, and thermogravimetry-Fourier transform infrared spectroscopy-mass spectrometry. There were certain differences in the weight loss temperature, time, residual mass, and activation energy of the samples in the pyrolysis reaction. After ageing, the production of acetic acid and methane in ethylene vinyl acetate pyrolysis products increased, while the production of CO2 decreased. After ageing, Tedlar-Polyethylene Terephalate-Tedlar mainly produced water, carbon dioxide, and fluorocarbon compounds, and the percentage of harmful fluorocarbon compounds in the human body increased. Cyclosiloxane, CO2, and hydrocarbons containing C-H bond were detected in each weight-loss stage of aged silica gel. As the heating rate changed, the amount of pyrolysis products also changed. Controlling the sample's heating rate would help to lessen the quantity of hazardous pollutants that were produced. The influence of ageing on the weight loss of mixed samples was discussed. This study seeks to give a fundamental understanding of the physicochemical properties, pyrolysis behaviour, and volatiles of samples before and after ageing, thus providing helpful insights for the final disposal or recovery of waste photovoltaic panels through pyrolysis.

Erratum to: Water/Oil-Repellent Cotton Fabrics Prepared Using Fluorocarbon Compounds, Polyurethane Cross-linker, and Silica Nanoparticles

Erratum to: Water/Oil-Repellent Cotton Fabrics Prepared Using Fluorocarbon Compounds, Polyurethane Cross-linker, and Silica Nanoparticles

Computational Insights into Degradation Probability of Small Fluorocarbon Compounds

Computational Insights into Degradation Probability of Small Fluorocarbon Compounds

Mechanically robust hydrophobic fluorine-doped diamond-like carbon film on glass substrate

Development of hydrophobic surfaces with a low friction coefficient is an impressive strategy for improving performance of self-cleaning glasses and photovoltaic cells. To this end, diamond-like carbon (DLC) films have been fabricated by plasma-enhanced chemical vapor deposition (PECVD) by varying the fluorine concentration of the film. As fluorine is introduced to the DLC film, some fluorocarbon compounds, including CF and CF2 and also CF3, are formed as confirmed by X-ray photoelectron spectroscopy (XPS). Additionally, the Raman spectroscopy analysis revealed a decrease in the sp3/sp2 hybridization ratio of carbon atoms as the fluorine concentration increased in the DLC films. It is believed that the presence of fluorocarbon compounds on the surface and high surface roughness are the key factors responsible for the high hydrophobicity of the fluorine-doped DLC films. Nano-scratch and nanoindentation tests indicated a significant relationship between fluorine content and mechanical properties of the DLC films. The hardness and elastic modulus of the film were decreased by increasing the fluorine content of the film. With incorporation of fluorine (19.2 at.%) into the DLC film, the friction coefficient of 0.2 was obtained. The potential of the fluorine-doped DLC films with a moderate concentration of fluorine (19.2 at.%) was confirmed as a robust interface with adequate hydrophobicity for surface engineering of self-cleaning glasses.

A Mass Spectrometry-Machine Learning Approach for Detecting Volatile Organic Compound Emissions for Early Fire Detection.

Mass spectrometry in parallel with real-time machine learning techniques were paired in a novel application to detect and identify chemically specific, early indicators of fires and near-fire events involving a set of selected materials: Mylar, Teflon, and poly(methyl methacrylate) (PMMA). The volatile organic compounds emitted during the thermal decomposition of each of the three materials were characterized using a quadrupole mass spectrometer which scanned the 1-200 m/z range. CO2, CH3CHO, and C6H6 were the main volatiles detected during Mylar thermal decomposition, while Teflon's thermal decomposition yielded CO2 and a set of fluorocarbon compounds including CF4, C2F4, C2F6, C3F6, CF2O, and CF3O. PMMA produced CO2 and methyl methacrylate (MMA, C5H8O2). The mass spectral peak patterns observed during the thermal decomposition of each material were unique to that material and were therefore useful as chemical signatures. It was also observed that the chemical signatures remained consistent and detectable when multiple materials were heated together. Mass spectra data sets containing the chemical signatures for each material and mixtures were collected and analyzed using a random forest panel machine learning classification. The classification was tested and demonstrated 100% accuracy for single material spectra and an average of 92.3% accuracy for mixed material spectra. This investigation presents a novel technique for the real-time, chemically specific detection of fire related VOCs through mass spectrometry which shows promise as a more rapid and accurate method for detecting fires or near-fire events.

Investigation of the Usage Characteristics of Environmentally Friendly Water-Repellent Chemicals on Cotton Fabrics

Fabrics with water-repellent properties are widely valued in the textile industry. It is known that fluorocarbon compounds, which are widely used for this purpose, are harmful to the environment. Therefore, within the scope of this study, a water-repellent chemical that does not contain fluorocarbon compounds was used to treat 100% cotton fabrics and compared with fluorocarbon compounds. The results show that the environmentally friendly chemical is at least as effective as the fluorocarbon compounds. According to the spray test, water repellency at ISO 5 level was obtained. In addition, the fabrics’ usage properties were assessed and high water vapour permeability, air permeability and low bending stiffness (280 mg cm) were obtained. This has yielded important results in terms of sustainability and the potential for eliminating the use of fluorocarbons for this application.

SURFACE PROPERTIES OF FLUOROCARBON COATINGS PRODUCED BY LOW-FREQUENCY PLASMATRON AT ATMOSPHERIC PRESSURE

This paper presents the results of studies conducted on coatings based on thin fluorocarbon films obtained by plasma-enhanced chemical vapor deposition using low-frequency plasmatron and low-temperature plasma at atmospheric pressure. The possibility of forming thin fluorocarbon layers by supplying a cyclohexane/carbon tetrafluoride gas mixture to substrates made of polymeric materials (polyethylene terephthalate and polystyrene) has been demonstrated and the main technological modes of deposition process have been established. The absorption spectra of the obtained coatings were studied, the influence of the gas discharge energy contribution on the concentration of fluorocarbon compounds was established, and the band gap was calculated using the Tauc method. The surface relief of the obtained structures was considered using atomic force microscopy and the root-mean-square deviation of the surface roughness was calculated, which reached a maximum of 36 ± 3 nm. Using the Oliver-Pharr method, the nanohardness and Young's modulus of elasticity of the obtained coatings were calculated, which amounted to 0.447 ± 0.025 and 6.10 ± 0.39 GPa, respectively.

Characteristics of generated aerosol suspensions-complexes at traditional and modernized aluminum electrolysis technologies

Introduction. Assessment of occupational risk and mechanisms of workers' health disorders due to exposure to complex aerosol suspensions determines the need for in-depth study of the physicochemical properties of dust particles in the air. The study aim was the assessment of the dispersion and chemical composition of complex aerosol suspensions affecting workers in traditional and modernized aluminum production technologies. Materials and methods. The monitoring of air pollution of the working area with soluble and insoluble fluorides, aluminum trioxide aerosols was carried out using standard analysis methods, the dispersed and chemical composition of aerosol suspensions was studied using scanning electron microscopy and energy dispersive X-ray microanalysis. Results. The highest average shift concentration of fluorides, exceeding the occupational exposure limit by 4.7-12.5 times, are observed in the working area of professions serving electrolyzers and anodes, with a predominance of insoluble fluorides over soluble ones. Cases of exceeding the occupational exposure limit of aluminum trioxide by 1.9-2.6 times were noted. Dust suspended in the air of the working area consists of highly and ultradispersed aerosol mixtures of various chemical nature, including particles of the nanoscale range, impurities of heavy metals and toxic compounds. Highly dispersed dust particles, mainly alumina and fluorocarbon compounds, dominated in the air of workshops with traditional aluminum electrolysis technology, while micro- and nanoparticles, consisting mainly of cryolite and a mixture of aluminum fluoride with alumina, dominated in the modernized one. Conclusion. The exposure of complex multicomponent aerosol mixtures of aluminum production can pose a danger to the health of workers, which requires an in-depth analysis of the chemical and dispersed composition of aerosols when assessing the exposure of the dust factor and improving the complexes of preventive measures to prevent the development of diseases.

Effect of Oxygen on Power Frequency Breakdown Characteristics and Decomposition Properties of C5-PFK/CO2 Gas Mixture

This study explores the effect of O2 as the second-component buffer gas on the power frequency breakdown characteristics and decomposition products of C5-PFK/CO2 gas mixture. It is found that the breakdown voltage of C5-PFK/CO2 gas mixture containing 7.5% C5-PFK is about 1.4 times that of CO2 gas and about 2/3 of SF6 gas at the same pressure. Although the average breakdown voltage of C5-PFK/CO2/O2 gas mixture is slightly lowered, the addition of O2 reduces the standard deviation of the breakdown voltage, improving the insulation stability of the C5-PFK/CO2 gas mixture. The decomposition by products of C5-PFK/CO2 gas mixture include CO, CO2, CF4, COF2, C2F4, C2F6, C3F6, C3F60, C3F8/, C4F10, CHF3, C3HF7 and other fluorocarbon compounds. C5-PFK/CO2/O2 gas mixture with 4% O2 produces much CF4, C2F6 and less CO after breakdown. It is recommended to add 4 to 6% O2 in C5-PFK/CO2 gas mixture to improve the power frequency breakdown characteristics for engineering application.

Study on discharge decomposition characteristics of environmentally friendly gas C6F12O/CO2

Recently, finding a new environmentally insulating medium which can replace SF6 has become a research hotspot in the power industry field in recent years. Current research shows that C6F12O has good environmental performance and dielectric strength. In order to further explore the potential of C6F12O/CO2 mixed gas used in medium and low-voltage level electrical equipment, this paper has explored its decomposition characteristics through theoretical calculations and power frequency breakdown tests. First, the formation process of C6F12O decomposition products is calculated by using density functional theory. Then, the decomposition products of C6F12O/CO2 gas mixture with 6% C6F12O was detected by GC-MS after 50 times power frequency breakdown tests. Theoretical calculations show that the C–C bond and C–F bond in the C6F12O molecule are broken to form free radicals CF3•, C2F5•, C3F7• and F atoms, and then they further combine to form fluorocarbon compounds CF4, C2F6, C3F8, C3F6 and C5F12. Among them, the reactions of forming CF4, C2F6 and C3F8 are easier to occur. In the temperature range of 0–1000 K, with the temperature rising, the energy of the main decomposition products does not change much. At the same time, the experimental results show that the breakdown voltage of C6F12O/CO2 mixed gas with 6% C6F12O is about 1.5 times that of pure CO2 under 0.14 MPa. The components and content of the decomposition products are consistent with the theoretical calculation results. The above conclusions can provide theoretical basis and engineering guidance for the application of C6F12O/CO2 mixed gas.

C4F8 plasma treatment for the modification of the focal length of liquid-based plano-convex lenses on different substrates

In this contribution, we present a plasma-based approach for modifying the focal length of plano-convex lenses realised by the deposition of droplets made of optical cement. For this purpose, PMMA and soda-lime glass substrates were treated with a direct dielectric barrier discharge plasma at low pressure. To obtain plasma-induced changes in surface energy of the substrates by the formation of functional groups, octafluorocyclobutane (C4F8) was used as process gas. Such treatment lead to a notable decrease in surface energy and especially its polar fraction, which is attributed to the generation of fluorocarbon compounds such as polytetrafluoroethylene (PTFE) as also confirmed by FTIR spectroscopic measurements. It is shown that this effect has a considerable impact on the contact angle and radius of curvature, respectively, of the deposited cement droplets where differences by a factor of about two were obtained. After curing of the cement, front focal lengths in the range from approx. 5 to 13 mm were realised depending on the duration of the plasma pre-treatment. The cement lenses finally feature dimensions in the range of some millimetres.

The effects of fluoroalkyl chain length and density on siRNA delivery of bioreducible poly(amido amine)s

Fluorination is an attractive strategy for the improvement of transfection efficiency of nucleic acid delivery vectors. Bioreducible poly(amido amine)s (bPAAs) are an important class of biomaterials exhibited to effectively deliver multiple nucleic acids. However, still, the effects of fluoroalkyl chain length and density of bPAA on siRNA delivery are unveiled. Here, we synthesized bPAAs and grafted with different chain lengths and densities of fluorocarbon compounds. Furthermore, we prepared a library of complexes of fluorinated bPAA and siRNA, and investigated the effects of fluorination on the siRNA delivery in vitro and in vivo. We found that all the synthesized bPAAs readily formed complexes with siRNA and the fluorinated complexes considerably achieved improved gene silencing efficacies both in vitro and in vivo. Dramatically, the gene silencing efficacy was increased with increasing fluorine contents. Heptafluorobutyric anhydride (HF) modified bPAAs achieved better gene silencing efficacy when compared with bPAAs fluorinated by trifluoroacetic anhydride (TF) and pentafluoropropionic anhydride (PF) providing the evidence for choosing of best one among fluorocarbon compounds. In addition, a combination of fluorination with bioreducibility enables efficient and safe siRNA delivery.

Effect of Hydrophobic Chains on Solubilization of Hydrocarbon and Fluorocarbon Surfactant Mixtures in Aqueous Solution.

We investigated the solubilization behavior of the hydrocarbon surfactant lithium dodecyl sulfate (LiDS) and the fluorocarbon surfactant lithium 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluoro-1-octanesulfonate (LiFOS) in an aqueous solution to determine the controlled release mechanism of solubilizate. The LiDS system solubilized Sudan III, a hydrocarbon compound, whereas the LiFOS system did not, because of the immiscibility of the hydrocarbon and fluorocarbon compounds. The solubilization ability of the LiDS and LiFOS mixtures gradually decreased with increasing LiFOS bulk composition because the micelles mainly composed of LiDS transformed into micelles mainly composed of LiFOS. Furthermore, Sudan III solubilized in the aqueous LiDS was deposited when an aqueous LiFOS was added. The difference in the solubilization behavior between LiDS and LiFOS enabled the controlled release of the solubilizate.

Nanocomposite Synthesized in Plasma of Pulse High-Voltage Discharge Initiated between Copper Electrodes in the Presence of Fluoroplast

Abstract—Nanocomposites have been synthesized by the destruction of copper electrodes in the plasma of a pulsed high-voltage discharge in the presence of fluoroplast. Nanocomposites include copper-containing nanoparticles distributed in a carbon-fluorocarbon matrix made from chain nanofibrils. Calcining of the specimens has afforded coils from carbon nanoribbons. An identical behavior of magnetic susceptibility M(H) has been determined in initial and calcined specimens, which manifests itself in gradual changes at specific values of magnetic field, which suggests the existence of a Josephson contact environment at room temperature. High-molecular fluorocarbon compounds, which do not correspond to PTFE molecules, have been determined in the products of pyrolysis of initial specimens. A powder specimen consisting of the composite nanoparticles containing PTFE and these compounds has been prepared. It has been demonstrated that high-molecular fluoroorganic compounds, which are not poly(tetrafluoroethylene) molecules, are formed from fluoroplast molecules after exposure to the plasma of pulsed of high-voltage discharge on fluoroplast.

Fabricating durable, fluoride‐free, water repellency cotton fabrics with CPDMS

ABSTRACTThe demand for fluoride‐free and durable hydrophobic cotton fabric is dramatically increasing due to environmental and human safety concerns. The current approach to produce water repellent cotton fabrics is applying fluorocarbon compounds in topical treatments. However, the fluorocarbons employed in the water repellent treatments on cotton fabrics have environmental concerns and environmentally friendly technologies are desperately sought. Herein, we report a new approach of fabricating water repellent cotton fabrics with proper washing durability by using poly{dimethylsiloxane‐co‐[2‐(3,4‐epoxycyclohexyl)ethyl]methylsiloxane} (CPDMS) as a hydrophobic agent. Benefiting from formation of robust ether bonds between CPDMS and celluloses, the cotton fabrics could gain promising durability for daily laundry. The resultant cotton fabrics demonstrated simultaneously desired waterproofness (hydrostatic pressure up to 22 mbar), durability (hydrostatic pressure stabled at 12 mbar after five laundry cycles), and breathability. Moreover, the CPDMS modified cotton fabrics also exhibited robust physical property with tensile strength retention up to 73%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46396.

Pressure-Temperature-Induced Transformations of Hydrocarbon- Fluorocarbon Mixtures into Nano- and Micron-Size Diamonds

Studies of thermal transformations of naphthalene (С10Н8), fluorographite (CF1.1) and octafluoronaphthalene (С10F8) and their binary mixtures (С10Н8 – CF1.1, С10Н8 – C10F8) under pressure of 8 GPa have been undertaken as models for gaining understanding of processes of carbonization, graphitization and diamond formation in pure hydrocarbon, fluorocarbon and carbon-hydrogen-fluorine-containing systems under high pressures. The studies found a significant reduction in the initiation temperature thresholds for all major thermal transformation processes in case of binary mixtures with respect to thresholds for pure hydrocarbon and fluorocarbon compounds. Another distinctive feature of the transformations of binary mixtures with respect to diamond formation stage of the transformations of pure hydrocarbons, has been the presence of massive quantity of nanosize (10–60 nm) diamond fraction in the products from binary mixtures along with the micron-size (5–20 μm) diamond fraction, typically observed in the transformations of pure hydrocarbons. The origin of nanodiamond was related to the specifics of carbonization of fluorocarbon compounds under pressure, which at 800–1000 °С produces, along with submicron particles of graphite-like material, a significant amount of closed shell 2–5 layer carbon nanoparticles of 5–15 nm size. These onion-like carbon nanoparticles act as precursors for formation of nano size diamond fractions in the transformations of binary mixtures of hydrocarbon and fluorocarbon compounds. These results potentially open a new direction for metal catalyst-free synthesis of pure and doped diamonds for broad applications. The present article gives an overview of this emerging area of rese arch.

Comparative Study of Condensation Routes for Formation of Nano- and Microsized Carbon Forms in Hydrocarbon, Fluorocarbon, and Fluoro-Hydrocarbon Systems at High Pressures and Temperatures

Thermal transformations of binary mixtures of hydrocarbons and fluorocarbons under high pressures demonstrate significantly lower initiation temperature thresholds for all major transformation stages, including carbonization, graphitization, and diamond formation, than the transformations of pure hydrocarbon and fluorocarbon components. In addition, along with the formation of micrometer-size diamond fraction, typical for transformation products of pure hydrocarbons, massive formation of nanosize diamond fraction has been observed in the products of conversion of mixtures. In order to gain understanding of the nature of simultaneous formation of micro- and nanosize fractions of diamond in the binary mixtures of hydrocarbon and fluorocarbon compounds, a comparative studies of the attributes of thermal transformations of pure hydrocarbon, fluorocarbons and their homogeneous and heterogeneous mixtures has been carried out under pressure of 8 GPa and temperatures up to 1500 °C. Naphthalene (C10H8) and octaflu...

Fluorocarbon compounds in MRI diagnostics and medical therapy

The lecture describes the application of fluorocarbon compounds as blood substitutes and contrasting preparations in MRI diagnostics. A blood substitute product fluorocarbon Perfluorane® has shown effectiveness in oxygen delivery to the tissues of living organisms, and cardioprotective effect which does not depend on the patient's blood group. Inclusion of paramagnetic atoms (gadolinium, iron, etc.) to the Perfluorane® chemical formula creates a new compound with high MRI contrast efficiencies at Larmor frequencies of protons so and fluorine-19 nuclei.

Study on Colloid Vibration Current in Aqueous Solution of Binary Surfactant Mixtures: Effects of Counterions and Hydrophobic Chains.

In order to elucidate an electroacoustic phenomenon of mixed micelles in an aqueous solution, we measured the colloid vibration current (CVI) in aqueous solutions of binary surfactant mixtures. Based on the thermodynamic treatment of critical micelle concentration (cmc) values determined by conductivity measurements, it was expected that dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium chloride (DTAC) molecules would mix ideally in the micelle. However, the micelle composition as evaluated from the CVI measurement, based on the linear dependence of the CVI value on the micelle composition, differed from the aforementioned ideality. Considering these observations, we concluded that the CVI measurement was more sensitive to the counterion distribution near the micelle surface, whereas the thermodynamically determined micelle composition included the counterions more loosely bound in the diffuse double layer due to the electroneutrality condition included in its assumption. On the other hand, the phase diagram illustrating micelle formation in the lithium dodecyl sulfate (LiDS) - lithium perfluorooctane sulfonate (LiFOS) mixture system showed a heteroazeotropic point arising from the stronger interactions between homologous surfactants than between heterologous ones. Although the concentration dependence of CVI values was expected to drastically change at a heteroazeotropic point due to the enormous variation in the density of the micelle core, the results showed a monotonous change, which suggests that the density of the micelle core varies continuously. By taking the partial molar volume of fluorocarbon compounds in the hydrocarbon compounds into account, the density of the micelle core was affected by the size of the micelle as well as its constituents.

Multinuclear Magnetic Resonance Imaging and NMR Spectroscopy in Biomedical Investigations

Biomedical investigations with small animals using 0.5-T and 7-T MRI scanners adjusted on the Larmor frequencies of different nuclei 1H, 2H, 11B, 13C, 19F, 23Na, 31P, 35Cl are described. Experiments on registration of signals 19F from the fluorocarbons injected in laboratory animals are discussed. They give presentation on the application of fluorocarbon compounds as blood substitutes and contrasting preparations in MRI diagnostics. A blood substitute product fluorocarbon Perfluoranum® has shown effectiveness in oxygen delivery to the tissues of living organisms, and cardioprotective effect which does not depend on the patient's blood group. Inclusion of paramagnetic atoms (gadolinium, iron, etc.) to the Perfluoranum® chemical formula creates a new compounds with high MRI contrast efficiencies at Larmor frequencies of protons so and fluorine-19 nuclei.