Plasma-treated Samples Research Articles

Nano-ZrO2@C, Nano-(ZrC, ZrO2)@C and Nano-ZrC@C Composites Prepared by Plasma-Assisted Carbonization of Zr-Loaded Iminodiacetate-Functionalized Styrene-Divinylbenzene Copolymers

We have developed an easy route to prepare (nano-ZrO2,nano-ZrCx)@C composites with varying ZrO2/ZrCx content. The process consists of preparing a zirconium-loaded, iminodiacetate-functionalized styrene-divinylbenzene (STY-DVB) copolymer, and its subsequent carbonization in a tube furnace and/or a thermal plasma reactor. Depending on the zirconium salt used (zirconyl chloride, zirconyl nitrate or zirconium (IV) sulfate) in the Zr loading, the Zr-loaded resins resulted in ZrO2@C pre-pyrolizates with C to Zr molar ratios of 5.8, 6.8 and 6.60. This carbon surplus is sufficient for the partial or even complete reduction of ZrO2 into ZrC0.58 at 1400 °C. The reaction products also contain 5 to 55 mass% residual free carbon. The plasma processing of the ZrO2@C composite formed at 1000 °C in a tube furnace led to ZrC0.94@C composites. The transformation of amorphous carbon content during the plasma treatment strongly depended on the atmosphere (He or H2) in the reactor and the anion type of the Zr salt. In the presence of He, amorphous carbon could be completely transformed into graphite. In the presence of H2, amorphous carbon and graphite were found at roughly the same ratio. No ZrO2 could be detected in the plasma-treated samples, whilst different ZrO2 polymorphs were found in the samples prepared in the tube furnace, depending on the synthesis conditions.

Study of the Effect of Plasma Treatment on the Mechanical Properties of Mineral Fiber Threads

The article describes methods for modifying glass and basalt fibers and threads, and composite materials from them. Special attention is paid to plasma methods. Twisted glass thread and basalt twisted thread are investigated in the work. Plasma treatment was used to modify the threads. The type of plasma is nonequilibrium, low-temperature; the type of discharge is high-frequency capacitive. The results of research of thread properties, such as morphological changes and breaking load of threads. The plasma-treated and non-treated samples of threads were compared. The modes of plasma modification of threads in which the increase of breaking load strength of glass threads up to 23 % and of basalt threads up to 10 % is achieved have been established.

The impact of combination of solution plasma processing and pulsed electric field on the viability of probiotic bacteria, microbial growth, and structure of yoghurt drink

In this study, the properties of the milk treated with combination of solution plasma (SP) processing and pulsed electric field (PEF) for different periods (5 and 10 min) was investigated. The microbiological, physicochemical, and sensory properties of the probiotic yoghurt drink (Ayran) produced from these milks were determined during storage. PEF was performed at voltage 3500 V, repetition 17,000 Hz, and pulse width 2.58 μs on the raw milk. Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis probiotic cultures were used in production with conventional yoghurt bacteria Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. In addition to the probiotic viability, texture and sensory quality in terms of consumer preference were investigated. It was determined that the viscosity and dry matter values of the solution plasma-treated samples were lower compared to the samples produced by heat treatment, and these values decreased further with the increase in plasma application time. It was also found that the maximum increase in L* and b* values of all samples during storage was in the samples treated with plasma for 10 min. The viability of the probiotic bacteria in probiotic Ayran samples were determined to be within the therapeutic level (>6.27 log10 cfu ml−1) with higher scores for sensorial qualifications. Practical applications Consumers’ expectations of more nutritious and microbiologically safe food have enabled the development of new processing technologies. Probiotic fermented milk products are products that provide health benefits in the prevention of gastrointestinal diseases, regulation of metabolism, and stimulation of the immune system. The processing of these dairy products with non-thermal technologies provides advantages in preserving their functional properties.

In Situ Synthesis of Copper Nanoparticles on Dielectric Barrier Discharge Plasma-Treated Polyester Fabrics at Different Reaction pHs.

Polyester (PET) fabrics are widely applied in functional textiles due to their outstanding properties such as high strength, dimensional stability, high melting point, low cost, recyclability, and flexibility. Nevertheless, the lack of polar groups in the PET structure makes its coloration and functionalization difficult. The present work reports the one-step in situ synthesis of copper nanoparticles (CuNPs) onto the PET fabric employing sodium hypophosphate and ascorbic acid as reducing and stabilizing agents, at acidic (pH 2) and alkaline pH (pH 11). This synthesis (i) used safer reagents when compared with traditional chemicals for CuNP production, (ii) was performed at a moderate temperature (85 °C), and (iii) used no protective inert gas. The dielectric barrier discharge (DBD) plasma was used as an environmentally friendly method for the surface functionalization of PET to enhance the adhesion of CuNPs. The size of the CuNPs in an alkaline reaction (76-156 nm for not treated and 93.4-123 nm for DBD plasma-treated samples) was found to be smaller than their size in acidic media (118-310 nm for not treated and 249-500 nm for DBD plasma-treated samples), where the DBD plasma treatment promoted some agglomeration. In acidic medium, metallic copper was obtained, and a reddish color became noticeable in the textile. In alkaline medium, copper(I) oxide (Cu2O) was detected, and the PET samples exhibited a yellow color. The PET samples with CuNPs presented improved ultraviolet protection factor values. Finally, a minimal concentration of copper salt was studied to obtain the optimized antibacterial effect against Staphylococcus aureus and Escherichia coli. The functionalized samples showed strong antibacterial efficacy using low-concentration solutions in the in situ synthesis (2.0 mM of copper salt) and even after five washing cycles. The DBD plasma treatment improved the antibacterial action of the samples prepared in the alkaline medium.

Effect on Physical and Thermal Properties of Corn Starch Treated by Energetic N₂ Extracted From Glow Discharge Plasma

In a typical nitrogen glow discharge plasma, a large number of energetic neutrals, N₂, are generated inside the cathode sheath. In this work, we are presenting a technique for the extraction of this energetic N₂ for the treatment of starch. The energetic neutrals N₂ were generated by the application of −500 V on a transparent cathode. On reaching the cathode, N₂^+ ions are absorbed; however, it is transparent to energetic N₂ neutrals molecules generated inside the sheath by charge exchange collisions, as the energetic N₂ neutrals are unaffected by the electric field and pass through the transparent cathode. The sample for treatment was placed below the transparent cathode and thus exposed to the energetic N₂ neutrals extracted from glow discharge plasma for a duration of 30 min. The impact of energetic N₂ neutral extracted from glow discharge plasma results in modification of physical and thermal properties of corn starch (maize starch). The physicochemical and morphological properties of treated and untreated samples were studied. The surface roughness of the plasma-treated corn starch increased significantly in comparison to the untreated sample. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) spectra confirmed that there is a considerable reduction in the semicrystalline nature and the polymer structure morphology of the corn starch. Scanning electron microscope (SEM) micrographs of samples show a substantial change in surface morphology and in size of the grains between the plasma-treated and untreated corn starch samples. The room-temperature thermal properties of the plasma-treated corn starch samples are measured using differential scanning calorimetry (DSC). The results confirm that the starch treated with energetic N₂ molecules has a lower gelatinization temperature and could be applied in food processing industries.

Passivation effect on the surface characteristics and corrosion properties of yttrium oxide films undergoing SF6 plasma treatment

This study investigates the structures, compositions and fluorocarbon-plasma etching behaviors of yttrium oxyfluoride (YOF) passivation films fabricated on sputter-deposited yttrium oxide (Y2O3) by high-density SF6 plasma irradiation. High-resolution transmission electron microscopy and nano-beam electron diffraction confirmed a YOF passivation film containing multiple phases of (104) and (006) crystal planes was formed on the fluorinated Y2O3 surface. X-ray photoelectron spectroscopy revealed few changes in the chemical compositions and surface roughness of the YOF passivation film after fluorocarbon plasma etching, confirming the chemical stability of the SF6 plasma-treated Y2O3 sample. The etching depth was ∼20% lower on the SF6 plasma-treated Y2O3 film than on the commercial Y2O3 coating. These results showed that the SF6 plasma-treated Y2O3 films have an excellent erosion resistance properties compared to the commercial Y2O3 coatings.

Bulk Polymerization of PEGDA in Spruce Wood Using a DBD Plasma-Initiated Process to Improve the Flexural Strength of the Wood–Polymer Composite

The chemical treatment of wood has been shown to increase its mechanical strength by forming composites with a variety of polymers. Polyethylene glycol diacrylate (PEGDA) has commonly been used as a polymer reinforcement to increase the strength and resistance of spruce wood for various applications, such as protection from weathering. In this study, PEGDA was impregnated into wood samples and polymerized by dielectric barrier discharge (DBD) plasma to form wood–polymer composites (WPCs). The kinetic rate order of PEGDA was explored using FT-IR quantitative analysis and the DBD plasma-initiated polymerization was determined to be second order. The strength of the wood samples was then determined by a three-point flexural test. The PEGDA-treated spruce wood samples showed improved flexural strength versus the untreated wood samples. The WPCs were also made using a UV treatment method and were then compared to the DBD plasma-treated samples. The results showed that the DBD plasma-treated samples yielded superior flexural strength relative to the UV-treated samples. We accredited this difference in strength to the plasma process and its ability to penetrate into the various layers of the wood and initiate polymerization, as opposed to UV light that can only penetrate superficially, initiating polymerization in only the first few layers of the wood surface.

Effect of Low-Pressure Plasma Treatment on the Surface Wettability of Poly(butylene succinate) Films

Poly(butylene succinate) (PBS) films were processed by a radio frequency (RF; 13.56 MHz) low-pressure plasma of oxygen and argon/oxygen, and an oxygen plasma with an argon post-crosslinking plasma to improve their wettability property. Specimens were treated at different times with fixed power processing of 100 W (0.3 W/cm2) and a fixed pressure of 10 Pa. A significant change in hydrophilicity evaluated by the water contact angle was observed. The contact angle of a water drop decreased from 80° for the untreated sample to values lower than 5° for plasma-treated samples. The effect of ageing on the wettability of PBS substrates was also examined, showing a more pronounced trend in the first 4 h and reaching a plateau in the following days. However, partial surface hydrophilicity was maintained for up to 15 days. A practical application of the surface functionalization produced by plasma was obtained via the deposition of SiOx onto PBS surfaces; the study of films’ oxygen permeability demonstrated that the plasma pre-treatment increased the adhesion between PBS and SiOx, resulting in significantly improved oxygen barrier properties. In order to evaluate the morphology and roughness modification caused by plasma exposure, atomic force microscopy characterization was carried out. Chemical information about treated surfaces, such as an increase in oxygen functional groups during plasma exposure, was measured by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Finally, the effects of plasma on crystallinity were investigated by X-ray diffraction.

Performance of non-thermal plasma reactor for removal of organic and inorganic chemical residues in aqueous media

In this work, the performance of an atmospheric air-assisted plasma reactor was evaluated for the oxidative degradation of azo (orange G and congo red) and non-azo (crystal violet, and coomassie brilliant blue) textile dyes and removal of hardness in an aqueous medium. Dye degradation efficiency was evaluated at different applied voltages (2–6 kV), pH (2.85–11.44), and initial dye concentrations (5–25 ppm). Nearly 99% degradation efficiency (at 5 ppm concentration) could be achieved in 30 min treatment time for all dyes. Degradation efficiency showed a direct relationship with applied voltage and an inverse relationship with the initial dye concentration. Moreover, higher degradation efficiencies were observed at neutral pH than in the acidic and alkaline ranges. The pseudo-first-order kinetic model exhibited a better correlation coefficient (R2 > 0.90) in explaining the degradation kinetics of dyes. The water hardness was dropped by 55.5% after 60 min of plasma treatment. Also, the crystalline structure and morphology of water samples containing salts before and after the treatments were analyzed using XRD and SEM. The average crystalline size of untreated and plasma-treated samples is calculated to be 197.9 nm and 98.1 nm respectively. The concentration of O3, OH., H2O2, NO2− and ROS species increased linearly with increasing treatment time. The energy yield and energy consumption for degradation and water hardness removal were ∼0.016 g kW/h and ∼0.3932 g kW/h, 1.08*107 J/L, and 2.16*106 J/L respectively. Moreover, atmospheric pressure gliding arc discharge-based air plasma discharge was computationally modeled and electrical characteristics such as electron density, electric potential, electron temperature, absolute electron flux and charged species (positive and negative) density were examined at different applied voltages. Overall, the atmospheric air-assistant cold plasma process shows promising potential for the removal of chemical residues in water.

Определение модуля упругости нанопокрытия с помощью испытания на трехточечный изгиб

Technologies for creating nanocoatings with unique properties on polymeric materials are being actively developed and used in human activities. The possibilities of using such composite materials will depend on the physical and mechanical properties of the coatings. To determine the mechanical characteristics of nanocoatings on polymeric materials, there are used nanoindentation methods. The results of nanoindentation of a hard coating are significantly affected by a soft polymer substrate. On the other hand, there are various experimental methods and analytical models for determining the mechanical properties of materials at the macroscopic level. The use of these approaches would make it possible to obtain the values of the mechanical properties of nanocoatings, which could be used to calculate and analyze the stress-strain state of products with nanocoatings. In this study, we demonstrate the application of a three-point bending test to determine the elastic modulus of a carbonized nanolayer formed by high-energy nitrogen ion treatment of a polyurethane surface. By selecting the optimal thickness of the test samples, it is possible to create conditions for determining the modulus of elasticity of a nanolayer on a polymer substrate using a three-point bending test. We have obtained statistically significant differences between the values of the elastic modulus of untreated and plasma-treated samples. Using a composite beam model, the modulus of elasticity of the carbonized nanolayer was determined.

WATER REPELLENT BREATHABLE PET/WOOL FABRIC VIA PLASMA POLYMERISATION TECHNOLOGY

Water-repellent textiles are usually prepared by application of hydrophobic polymers such as fluorocarbons on fabrics using padding or spraying methods followed by drying and curing steps. These procedures impart hydrophobicity to the fabric, but harm the physical and handle properties of the fabric. In this study, low-pressure plasma was employed for the polymerization of 1H,1H,2H,2H-Perfluorooctyl acrylate on PET/Wool fabric for obtaining water-repellent properties with minimum effect on other desirable properties. To compare the results with the conventional industrial processes, a sample was treated with a commercial water-repellent agent using pad-dry-cure method. The water contact angle, bending length, tensile strength, air permeability, and surface morphology of the samples were compared. The plasma-treated sample showed similar water contact angle and higher fastness properties compared with the sample prepared by the conventional method. The tensile strength of the samples was similar, while the air permeability of the plasmatreated sample was higher and the coating was more uniform compared with the sample prepared by the paddry- cure method.

Investigating the Cold Plasma Surface Modification of Kaolin- and Attapulgite-Bound Zeolite A

Hydrophilic zeolites with low catalytic activity are considered as suitable adsorbents for drying gas streams containing olefinic compounds. In this contribution, the surface treatment of kaolin and attapulgite/zeolite A extrudates is investigated using argon glow discharge plasma. The zeolite is synthesized from kaolin using the hydrothermal method. Surface and bulk characterization is performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 physisorption, Fourier-transform infrared (FT-IR) spectroscopy, temperature-programmed-desorption (TPD) of NH3 and X-ray photoelectron spectroscopy (XPS) techniques. Plasma treatment increases surface area and pore volume, but it decreases the weak acidic site density of the extrudates. The obtained results show that attapulgite/zeolite extrudates are more affected by plasma treatment than kaolin/zeolite extrudates. The catalytic activity of untreated and plasma-treated extrudates are compared with respect to coke formation resulting from 1-butene and 1,3-butadiene. The plasma-treated sample is more resistant to coke formation (∼35% decrease compared to untreated one). The potassium contents of extrudates decreased as a result of sputtering loosely bound potassium cations on the crystal surface by argon ions, which led to a decrease in water sorption capacity (by ∼15% of the initial sorption capacity).

Low defect and high electrical conductivity of graphene through plasma graphene healing treatment monitored with in situ optical emission spectroscopy

Fundamental studies on graphene (Gr) and its real device applications have been affected by unavoidable defects and impurities which are usually present in synthesized Gr. Therefore, post treatment methods on Gr have been an important subject of research followed by the community. Here, we demonstrate a post-treatment of cm-sized CVD-grown graphene in a Radio Frequency-generated low-pressure plasma of methane and hydrogen to remove oxygen functional groups and heal the structural defects. The optimum plasma treatment parameters, such as pressure, plasma power, and the ratio of the gases, are optimized using in-situ optical emission spectroscopy. This way we present an optimal healing condition monitored with in situ OES. A twofold increase in the conductivity of plasma-treated Gr samples was obtained. Plasma treatment conditions give insights into the possible underlying mechanisms, and the method presents an effective way to obtain improved Gr quality.

Application of Fragrance Microcapsules onto Cotton Fabric after Treatment with Oxygen and Nitrogen Plasma

Cotton fabric was exposed to low-pressure capacitively coupled plasma to enhance the adsorption and adhesion of fragrance microcapsules (FCM). Two plasma-forming gases, namely oxygen (O2) and nitrogen (N2), were investigated. The untreated and plasma-treated samples were investigated for their morphological changes by scanning electron microscopy (SEM), mechanical properties (breaking force, elongation, and flexural rigidity), and wicking properties. The cotton samples were functionalized with FCM and the effect of plasma pretreatment on the adsorption and adhesion of FCM was evaluated using SEM, air permeability, fragrance intensity of unwashed and washed cotton fabrics, and Fourier transform infrared spectroscopy (FTIR). The results show that the plasma containing either of the two gases increased the wicking of the cotton fabric and that the O2 plasma caused a slight etching of the fibers, which increased the tensile strength of the cotton fabric. Both plasma gases caused changes that allowed higher adsorption of FCM. However, the adhesion of FCM was higher on the cotton treated with N2 plasma, as evidenced by a strong fragrance of the functionalized fabric after repeated washing.

Surface Characterisation of PEEK and Dentin, Treated with Atmospheric Non-Thermal PDD Plasma, Applicable for Dental Chair-Side Procedures

This study investigates the suitability of Piezoelectric Direct Discharge Plasma as a tool for wetting behaviour modification of PEEK and dentin, and compares the results of this method with low-pressure plasma treatment and phosphoric acid etching. Static contact angle measurements were made, roughness was assessed using tactile measurement, and AFM and SEM images were taken. An optimum operating distance of ≤15 mm was determined for the plasma based on the water contact angle. Furthermore, it was demonstrated that despite only a fraction of the power, the PDD plasma also produces hydrophilic and nanostructured PEEK surfaces with a 38° water contact angle in the same plasma time. In contrast, the gold standard of dental surface modification of dentin—phosphoric acid etching—showed no measurable contact angle due to the exposed dentin tubules. Treatment with PDD plasma reduces the water contact angle of dentin from 65° to 43° and is not negative affected by water. Wet, PDD plasma-treated dentin samples show a water contact angle of only 26.5°. The dentin tubules exposed by chemical etching led to a significantly increased roughness. No comparable effect could be demonstrated for plasma treatment on dentin, but based on the contact angle measurements, a chemically strongly activated surface with strongly polar interaction behaviour can be assumed. The additional use of the PDD plasma technique to improve wetting could therefore have a positive effect on the adhesive bond between human dentin and polymeric dental restorative materials or, depending on the adhesive system, replace the etching process altogether.

Bactericidal efficiency of silver nanoparticles deposited on polyester fabric using atmospheric pressure plasma jet system

Plasma technology offers an appealing approach for the surface modification of materials such as textiles. In this study, an atmospheric pressure plasma jet system was used to successfully deposit silver nanoparticles on polyester textile substrates to impart antibacterial properties. The plasma was generated by applying a constant potential of 15 kV to silver electrodes while argon and oxygen gases were allowed to flow at 15 and 5 LPM, respectively. The optical emission spectra of the generated plasma revealed the presence of argon, oxygen, and silver species. The combination of operating parameters employed in the study led to the successful deposition and adhesion of silver nanoparticles without changing the bulk properties of the material. The deposited silver nanoparticles were verified using a scanning electron microscope analysis which showed an expected increase in particle density at longer plasma exposure time. Qualitative and quantitative antibacterial assays proved the efficiency of the plasma-treated textile samples in inhibiting the growth of the Gram- negative Escherichia coli and the Gram-positive Staphylococcus aureus bacteria. The antibacterial efficiency of the treated samples proportionally increased with longer plasma treatment time. The approach used in this study successfully produced surface-immobilized silver nanoparticles polyester textile with potential application as antibacterial fabrics.

Developing Super-Hydrophobic and Abrasion-Resistant Wool Fabrics Using Low-Pressure Hexafluoroethane Plasma Treatment.

The growing interest in wool fibres as an eco-friendly and sustainable material for diverse industrial applications requires an enhancement of their functional performance. To address this, wool fabrics were treated in the present research with low-pressure hexafluoroethane (C2F6) plasma to impart superhydrophobicity and improve their abrasion resistance. Unscoured and scoured wool fabrics were treated with C2F6 while varying plasma power (80 W and 150 W), gas flow rate (12 sccm and 50 sccm) and treatment time (6 min and 20 min), and the effect of plasma parameters on the abrasion resistance, water contact angle and dyeing behaviour of the wool fabrics was studied. Martindale abrasion testing showed that the surface abrasion of the wool fabrics increased with the number of abrasion cycles, and the samples treated with 150 W, 20 min, 12 sccm showed superior abrasion resistance. The scoured wool fabrics showed a contact angle of ~124°, which was stable for only 4 min 40 s, whereas the plasma-treated samples showed a stable contact angle of over 150°, exhibiting a stable superhydrophobic behaviour. The C2F6 plasma treatment also significantly reduced the exhaustion of an acid dye by wool fabrics. The EDX study confirmed the deposition of fluorine-containing elements on the wool fabrics significantly altering their properties.

Cold Atmospheric Pressure Plasma Technology for Modifying Polymers to Enhance Adhesion: A Critical Review

This review summarizes the results of cold atmospheric pressure plasma technology application in polymers surface treatment. Attention is given to results of changes in the hydrophilic property of polymer surfaces by incorporation of polar functional groups when exposed to atmospheric pressure plasma, depending on the time of treatment, applied voltage, gas flow rate, and distance from the surface. We have successfully developed a plasma device that is able to generate cold atmospheric pressure argon plasma of low temperature (20 – 26) ° C downstream using a high-voltage power source which can be widely used in materials processing. Therefore, a cost-effective system of generating a plasma jet at atmospheric pressure with potential applications has been developed. Cold atmospheric pressure plasma jet (CAPPJ) has shown a lot of applications in recent years such as in materials processing, surface modification, and biomedical materials processing. CAPPJ has been generated by a high voltage (0-20 kV) and high frequency (20-30 kHz) power supply.<br/> The discharge has been characterized by optical and electrical methods. In order to characterize cold atmospheric pressure argon plasma jet, its electron density, electron temperature, rotational temperature, and vibration temperature have been determined using the power balance method, intensity ratio method, Stark broadening method, and Boltzmann plot method, respectively. The improvement in hydrophilicity of the cold plasma-treated polymer samples was characterized by contact angle measurements, surface free energy analysis, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). Contact angle analysis showed that the discharge was effective in improving the wettability of polymers after the treatment. Furthermore, atmospheric plasma can be effectively used to remove surface contamination and to chemically modify different polymer surfaces. The chemical changes, especially oxidation and cross-linking, enhance the surface properties of the polymers.

Potential Alternative to Nitrite in Roasted Lamb for Sensory Attributes: Atmospheric Nonthermal Plasma Treatment

Reducing or replacing sodium nitrite without compromising the sensory attributes of meat products has always been a focus of the meat industry. In this study, five treatments, CT (without nitrite and plasma treatment), NT (with nitrite treatment), PT15, PT30, and PT45 (without nitrite and with plasma treatment for 15, 30, and 45 min, respectively), were designed to investigate the effect of atmospheric nonthermal plasma treatment replacing nitrite on the sensory attributes of roasted lamb. Results showed that PT45 decreased the residual nitrite of roasted lamb by 30% compared with NT, and nitrite was not detected in the PT15 and PT30 samples. The inhibition effect of plasma treatment on the lipid oxidation reached values from 86.69% to 89.89% compared with NT. Compared with CT, the redness of plasma-treated samples was increased by 9.30% to 31.40%, and the redness of NT samples was increased by 30.87%. In addition, the volatile compounds (OAVs > 1) of the PT30 sample were higher than those of the NT sample. The overall sensory score of the PT30 sample was higher than that of the CT sample and was similar to that of the NT samples. In conclusion, the sensory attributes of roasted lamb were enhanced by plasma treatment, and the 30 min plasma treatment is recommended.

Study of the Influence of the Different Parameters of the Atmospheric DBD Treatment on the Surface Roughness and the Electric Potential Distribution Generated After the Tribocharging of Polypropylene

Square plates of polypropylene (PP), dimensions 100 mm × 100 mm × 4.5 mm, were treated by atmospheric dielectric barrier discharge (DBD) generated between two disk-type electrodes (Ø 75 mm), energized from an ac amplifier 30 kV, 20 mA. The study aimed at evaluating the factors that affect the roughness and the triboelectric behavior of the plasma-treated samples. The alteration of surface aspect after each treatment was clearly visible with the naked eye and the changes were confirmed by measurements carried out with a portable roughness meter (Surftest SJ-210) and a digital microscope (Keyence VHX-7000). The roughness of the PP samples increased from an initial arithmetic mean Ra = 0.06 μm (±0.01 μm) and standard deviation Rq = 0.08 μm (±0.01 μm) to Ra = 0.22 μm (±0.03 μm) and Rq = 0.25 μm (±0.03 μm), respectively. These increases were highly dependent on the air gap distance (10.5-13.5 mm), the treatment time (5-20 min), and the configuration of the DBD cell, i.e., the number (one or two) and the thickness (4-5 mm) of the glass dielectric barriers. Untreated and DBD-treated samples were tribocharged in a linear tribometer, to evaluate the effect of the cold plasma treatment on the electric potential generated on the polymer surface by the triboelectric effect. The electric potential measured by a noncontact electrostatic voltmeter (Trek, 341B) was higher and better distributed over the surface of the plasma-treated samples.