Ozone Surface Treatment Research Articles

Simultaneous measurement of electrical potential on both sides of the dielectric surface in a parallel-plate dielectric barrier discharges and analysis of net electric field

Dielectric barrier discharges (DBDs) are widely used for ozone generation and surface treatment owing to their ability to generate reactive species. Surface charges generated during discharges distort the electric field between the dielectrics and affect the generation of reactive species. Therefore, the net electric field variations are of significant interest. Herein, a DBD measurement system for the net electric field based on the Pockels effect is established for the first time. The proposed system can simultaneously measure the surface potentials on both sides of the dielectric, thereby obtaining the net electric field at the discharge gap. The net electric field distribution varies insignificantly with the magnitude of the applied voltage but significantly with gap length. Moreover, the breakdown electric field increases with a decreasing gap length. This study provides a physical explanation for microgap reactors, demonstrating that the electric field in a DBD can be manipulated.

Enhancing ozone production in dielectric barrier discharge utilizing water as electrode

Dielectric barrier discharge is widely used in applications such as ozone generation and surface treatment. This investigation studies the electrical diagnostics and ozone generation capability in a dielectric barrier discharge ozone generator utilizing water acting as the ground electrode for the first time. Results show that specific input energy peaks at 8 kHz when the frequency changes from 5 kHz to 10 kHz. Results also show that the maximum ozone generation efficiency reaches 391.66 g/kWh at discharge frequency of 6 kHz. At power frequency of 7 kHz, the ozone generation efficiency reaches 231 g/kWh and the ozone concentration reaches about 12293.59 ppm. In addition, by comparing with the results of previous studies in the literature, it is concluded that the using water flow as the ground electrode can achieve high ozone efficiency at high ozone concentrations. This investigation provides a new method for high efficient ozone production.

Creep behaviour of ozone treated jute fabric/epoxy composites

The present work attempted to study the creep behaviour of jute fabric/epoxy composites at different environment temperatures using several creep models (i.e., Burger’s model, Findley’s power law model, and Coupling model). The surface of jute fabrics was modified by ozone gas treatment to remove the non-cellulosic materials and thereby improve their adhesion with epoxy matrix. Further, the performance of ozone surface treatment was compared with traditional alkali treatment based on surface morphology, mechanical properties, hydrophilicity, etc. The ozone surface treatment was found to remove lignin and increase hydrophilicity of jute fibres to greater extent as compared to alkali treatment, however with higher tendency of defibrillation and fibre rupture. Later, the creep resistance of alkali treated jute fabric/epoxy composites was found superior to the ozone treated jute fabric/epoxy composites at lower temperature of 40°C and 70°C. However, the ozone treated jute fabric/epoxy composites showed higher instantaneous elastic deformation and lower viscous deformation at elevated temperatures of 70°C and 100°C. The ozone treated jute fabric/epoxy composites showed extended temperature range of 100°C–120°C to restrict segmental mobility of epoxy matrix and depicted higher interfacial shear strength properties from the microbead pull out test.

Communication—Power Enhancement of Fabric Triboelectric Energy Harvesters Using Ultraviolet Light and Fluoro-Based Treatment

Triboelectricity is a self-powered phenomenon that has recently attracted attention because it is capable of instantaneously generating a large amount of electrical power. In this study, we developed a method to fabricate a fabric-based triboelectric energy-harvesting device and enhanced the output of this device using a Fluorinert coating and ultraviolet (UV)/ozone surface treatment. Through simple surface treatment processes, the electrical output of triboelectric self-generation device will be significantly increased, and at the same time, it will present the possibility of being naturally suitable for next-generation electric clothing products.

Modulating the detection performance of solution processed stacked multilayer-MoS2 photodetectors upon ultraviolet–ozone surface treatment

Modulating the detection performance of solution processed stacked multilayer-MoS2 photodetectors upon ultraviolet–ozone surface treatment

Thermal properties and non-isothermal crystallization kinetics of biocomposites based on poly(lactic acid), rice husks and cellulose fibres

Bioplastics reinforced by agricultural waste fibres show promise to provide degradation back into the environment when they are no longer needed. These biocomposites have the potential to replace synthetic polymers from non-renewable resources in some applications and may turn out to be one of the material revolutions of this century. Unlike synthetic composites, biocomposites are renewable, carbon neutral, biodegradable and non-petroleum based and have low environmental, human health and safety risks. In this paper, poly(lactic acid) (PLA)-based biocomposites filled with technical cellulose fibres (CeF) and rice husks (RHs) at 10–30 mass% loading were prepared by twin-screw extrusion and injection moulding to enhance stiffness of resulting biocomposites. Particular attention was given to the enhancement of adhesion between the polymer matrix and natural filler through the physical modification by ozone (O3) and dielectric barrier discharge (DBD) plasma (p) surface treatments. Further than, compatibilizing agent based on PLA-g-MAH was produced and introduced into the PLA systems. The non-isothermal crystallization behaviour and thermal properties were investigated through differential scanning calorimetry (DSC) under various cooling rates (5, 10, 20 and 40 °C min−1). The addition of both fillers increased overall crystallization kinetics of resulted biocomposites, especially at high cooling rates. An increase in crystallinity degree from 2.4 (neat PLA) up to 51% has been observed for PLA/30CeFO3 samples at 40 °C min−1 cooling rate. An increase in crystallinity degree based on mass percentage of filler was noticed especially for PLA/RH. Mass percentage increase in CeF did not notice significant increase in PLA crystallinity. The influence of RH and CeF on transformation behaviours of PLA αʹ-/α-polymorphs was observed. The elimination of imperfect αʹ-crystals was observed with increasing amount of RH and CeF.

Factors That Affect Tribocharging of Polyethylene (PE) Granules After Exposure to a Dielectric Barrier Discharge (DBD)

Triboelectric charging is used in many applications including electricity nanogeneration, safety or electrostatic separation of insulating materials. Insulating granules charge must be the highest in electrostatic separators so that the electric field forces allow their separation. Dielectric barrier discharge (DBD), used for ozone production, depollution or surface treatment, is able to change the triboelectric properties of insulating materials. The aim of this study is to improve the triboelectric charging of polyethylene particles by exposing them to an atmospheric DBD. Signal shape, exposure duration, voltage amplitude, and frequency, which rule the DBD, are studied. After exposing the particles to DBD, they are charged in a vibratory device during 5 min. Then, particles are put in a Faraday pail connected to an electrostatic voltmeter to measure the acquired charge. Results show that the square waveform has the best effect and that the duration of the DBD treatment should not exceed 10 s, for the amplitude of the applied voltage of 21 kV.

An SDBD Plasma-Catalytic System for On-Demand Air Purification

Surface-dielectric-barrier discharges (SDBDs) can be applied for a wide range of applications, such as ozone generation, surface treatments, and air-pollutants removal. An important advantage of the SDBD plasma is that relatively low high-voltage (HV) pulses ( $1~\mu \text{s}$ and its ramp is about 6 kV/ $\mu \text{s}$ . The energy per pulse then ranges from 1.1 to 17.4 mJ. The output power can be adjusted up to 48 W at a repetition rate of 5.5 kHz. The maximum possible pulse repetition rate is 22 kHz, but it is limited to 5.5 kHz due to the limited current rating of the available dc power supply. The total energy efficiency of the power modulator is 68%. A single modulator unit can power up to two SDBD reactor plates of $100\times 150$ mm size, having plasma at both sides of the plate. The operational efficiency of the developed SDBD catalytic reactor has been investigated by studying the removal of NO x and ethylene. The removal efficiency of NO x and ethylene is determined as a function of energy density and operational parameters, such as their initial concentrations and the gas flow rate.

Controlled surface oxidation of multi-layered graphene anode to increase hole injection efficiency in organic electronic devices

Ultraviolet ozone (UVO) surface treatment of graphene changes its sp2-hybridized carbons to sp3-bonded carbons, and introduces oxygen-containing components. Oxidized graphene has a finite energy band gap, so UVO modification of the surface of a four-layered graphene anode increases its surface ionization potential up to ∼5.2 eV and improves the hole injection efficiency (η) in organic electronic devices by reducing the energy barrier between the graphene anode and overlying organic layers. By controlling the conditions of the UVO treatment, the electrical properties of the graphene can be tuned to improve η. This controlled surface modification of the graphene will provide a way to achieve efficient and stable flexible displays and solid-state lighting.

All-(111) surface silicon nanowire field effect transistor devices: Effects of surface preparations

Etching/hydrogen termination of All-(111) surface silicon nanowire field effect (SiNW-FET) devices developed by conventional photolithography and plane dependent wet etchings is studied with X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrical and electrochemical measurements. All measurements were carried out before and after etching with 1% HF, 40% NH4F, and 40% NH4F (N2) solutions and ozone surface treatments. AFM studies showed higher etching rates for the apex of the triangular nanowires. Stability of as prepared hydrogen terminated SiNW-FET surfaces and their electrical conductivity were considered. Surface etched devices were operated efficiently in an aqueous 0.02M KCl solution within a small potential window and a reference electrode was found to be essential. Retention of surface positive charges and inversion of p-type to n-type device character have been discussed.

Reducing the driving voltage of organic light-emitting diodes by inserting a transparent ultrathin layer of oxidized silver as a hole-injecting layer

Organic light-emitting diodes (OLEDs) containing a transparent ultrathin layer of oxidized silver as a hole-injecting layer, placed between a indium–tin-oxide (ITO) electrode and the hole-transporting layer, were fabricated, and their electrical and luminescent properties were investigated. The OLEDs had a structure that consisted of an ITO layer; followed by an ultrathin Ag layer oxidized by a ultraviolet (UV)–ozone surface treatment; a N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine (α-NPD) layer; a 5,6,11,12-tetraphenylnaphthacene (rubrene)-doped 9,10-diphenylanthracene (DPA) layer; a tris-(8-hydroxyquinoline) aluminum (Alq3) layer; a lithium fluoride (LiF) layer; and a Al layer. The operating voltages of the OLEDs with the oxidized Ag (i.e., AgOx) layer were drastically lower than those of the layer-free OLEDs, because the AgOx layer, which had high oxidizability, contributed to hole injection as it oxidized the surface of the α-NPD layer. However, the external quantum efficiency of the OLEDs with the AgOx layer was lower than that of the AgOx layer-free OLEDs, suggesting that the carrier balance (i.e., the balance between the holes and electrons) became uneven in the emission layer, owing to the insertion of the AgOx layer. It was assumed that this imbalance resulted from the number of holes in the emission layer being higher because of the increase in hole injection in the AgOx layer.

Effect of UV and UV–Ozone Treatment of Polyolefin Fibers on Toughness of Fiber Concrete Composite

Abstract Ultraviolet (UV) irradiation and a combination of UV irradiation and ozone treatment of polyolefin fibers were investigated for possible improvement of mechanical properties in concrete composites. In both treatment methods, various fiber exposure durations were used, and surface modification was monitored by measuring the water contact angle. Untreated and treated fibers were added to concrete at 0.32 % by volume, and the specimens were tested for flexural strength according to ASTM International specifications. Fiber surface treatment by UV alone was found to be an unattractive technique based on the results of flexural tests and contact angle measurements. Ten minutes of UV and ozone surface treatment of fibers was found to improve the composite peak stress by 11 % and the toughness by 4 %; longer periods of exposure led to lower flexural strength results, perhaps as a result of fiber deformation or degradation.

A-InGaZnO Thin-Film Transistor with Non-Vacuum Processed InGaZnO/AlOx Gate Dielectric Stack

We fabricated a thin-film transistor (TFT) with an amorphous InGaZnO (a-IGZO) and aluminum oxide (AlOx) gate dielectric stack that was deposited by a solution-based atmospheric pressure chemical vapor deposition. Field effect mobility of 4.1 cm2•V-1•s-1 and on/off current ratio of over 108 were obtained. We also investigated the effects of an ozone (O3) surface treatment of gate dielectric on electrical properties of the IGZO TFTs. The O3 surface treatment of the AlOx gate dielectric reduced the maximum area density of states in the IGZO TFTs. Moreover, transfer curve hysteresis also decreased by applying the O3 surface treatment of the AlOx gate dielectric.

Novel superhydrophobic top coating on surface modified PVC-coated fabric

A superhydrophobic surface was created on poly(vinylchloride)-coated architectural fabric using spray coating method. Dispersions of nanoparticles and a flourochemical were prepared as top coating solutions. After spray-dry-cure process, contact angle, sliding (tilt) angle, 3M water repellency test and surface morphology were compared between uncoated and top coated PVC surfaces. The results indicated that a specific nano-TiO2 dispersion top coating produced a superhydrophobic layer on the top of the PVC surface with high contact angle (150°) and very low sliding angle (2°). Combination of two major requirements, the magnified of the degree of roughness and low surface energy, created self-cleaning effect on the PVC surface. Abrasion fastness of superhydrophobic top coating was improved by surface oxidation via UV–ozone surface treatments. Spectroscopic analysis demonstrated that formation of oxygenated functional groups has improved PVC wettability and adhesion. Results of artificial weathering test indicated no change in superhydrophobicity of top coated PVC.

Solution processable silica thin film coating on microporous substrate with high tortuosity: application to a battery separator

A novel approach to incorporate a conformal inorganic thin layer inside 3D microporous polyolefin film is realized from a versatile solution process and applied to the preparation of a Li-ion battery separator with enhanced thermal and dimensional stability. Inorganic thin film thickness of around several tens of nanometers inside 3D micropores of a polyolefin could be systematically controlled by employing a mixed system of the silanization and epoxy–amine reaction of the UV-curable polymer and the plasma/UV ozone surface treatments. The surface-modified commercialized polyolefin separators with silica layers from the solution process show greatly improved thermal and dimensional stability compared to neat polyolefin separators, while maintaining charging/discharging performances of neat polyolefin separators, such as ionic conductivity, C-rate, and cycle life. Because of the conformal coating of the inorganic thin film inside the 3D polyolefin separator, the polyolefin separator maintains its initial dimension at high temperature, even above its melting point, which will result in improved safety of the Li-ion battery.

Tuning Nanoscale Friction on Pt Nanoparticles with Engineering of Organic Capping Layer

Nanoscale friction and adhesion on Pt colloid nanoparticles coated with different organic capping layers were probed with atomic/friction force microscopy. Platinum colloid nanoparticles with four types of capping layers have been synthesized and used as model lubricant systems: TTAB (tetradecyltrimethylammonium bromide), HDA (hexadecylamine), HDT (hexadecylthiol), and PVP (poly(vinylpyrrolidone)). Two-dimensional arrays of colloid nanoparticles were prepared using the Langmuir-Blodgett method. We found that the friction and adhesion properties on colloid nanoparticles are lower than those on a silicon surface. The variation of friction when changing the capping layers is ∼30%, and it appears that the friction depends on the packing and ordering of the capping layers. Partial removal of the capping layers using ultraviolet light (UV)-ozone surface treatment resulted in increased friction. These results suggest a new method of tuning nanometer scale friction and adhesion by engineering organic capping layers on nanoparticles.

Effect of surface oxidation treatment on the tribological performance of carbon fiber reinforced polyimide composites

AbstractThe effect of ozone surface treatment of carbon fibers (CF) on the tensile strength and tribological properties of carbon fiber reinforced polyimide (CF/PI) composite was investigated. Experimental results revealed that the tensile strength of ozone and air oxidation treated CF reinforced PI composite was improved compared with that of untreated composite. Compared with the untreated and air‐oxidated CF/PI composite, the ozone treated composite had the lowest friction coefficient and specific wear rate under given applied load and reciprocating sliding frequency. Ozone treatment effectively improved the interfacial adhesion between CF and PI. The strong interfacial adhesion of the composite made CF not easy to detach from the PI matrix, and prevented the rubbing‐off of PI, accordingly improved the friction and wear properties of the composite.

Effect of Carbon Fiber Surface Oxidation on Tribological Properties of PTFE Composite under Oil-Lubricated Conditions

Air-oxidation and ozone surface treatment of carbon fibers (CF) on tribological properties of CF reinforced polytetrafluoroethylene (PTFE) composites under oil-lubricated conditions was investigated. Experimental results revealed that ozone treated CF reinforced PTFE (CF/PTFE) composite had the lowest friction coefficient and wear under various applied loads and sliding speeds compared with untreated and air-oxidated composites. X-ray photoelectron spectroscopy (XPS) study of the carbon fiber surface showed that, after ozone treatment, oxygen concentration was obviously increased, and the amount of oxygen-containing groups on CF surfaces were increased greatly. The increase in the amount of oxygen-containing groups enhanced interfacial adhesion between CF and PTFE matrix, and large scale rubbing-off of PTFE was prevented; therefore, the tribological properties of the composite were improved.

The Tribological Properties of Oxidation-Treated Carbon Fiber-Reinforced PTFE Composite under Oil-Lubricated Conditions

The effect of air-oxidation and ozone surface treatment of carbon fibers (CF) on tribological properties of CF reinforced Polytetrafluoroethylene (PTFE) composites under oil-lubricated condition was investigated. Experimental results revealed that ozone treated CF reinforced PTFE (CF/PTFE) composite had the lowest friction coefficient and wear. X-ray photoelectron spectroscopy (XPS) study of carbon fiber surface showed that the increase in the amount of oxygen-containing groups enhanced interfacial adhesion between CF and PTFE matrix. With strong interfacial adhesion of the composite, stress could be effectively transmitted to carbon fibers; carbon fibers were strongly bonded with PTFE matrix.

The effect of carbon fibre surface oxidation on the friction and wear properties of polytetrafluoroethylene composites under oil-lubricated conditions

In this study, the effect of air oxidation and ozone surface treatment of carbon fibres (CFs) on tribological properties of CF-reinforced polytetrafluoroethylene (PTFE) composites under oil-lubricated condition was investigated. Experimental results revealed that ozone-treated CF-reinforced PTFE (CF/PTFE) composite had the lowest friction coefficient and wear compared with untreated and air-oxidated composites. An X-ray photoelectron spectroscopy study of the CF surface showed that, after ozone treatment, oxygen concentration was obviously increased, and the amount of oxygen-containing groups on CF surfaces was largely increased. The increase in the amount of oxygen-containing groups enhanced interfacial adhesion between CF and PTFE matrix. With strong interfacial adhesion of the composite, CFs were strongly bonded with PTFE matrix, and large-scale rubbing-off of PTFE was prevented; therefore, the tribological properties of the composite was improved.