Vlasta Štěpánová

The Multi-hollow Surface Dielectric Barrier Discharge (MSDBD) generated in ambient air at atmospheric pressure was used to treat maize, pea, wheat and parsley seeds. Plasma exposure was applied as a pre-treatment before the seeds coating with agrochemicals. The aim of this study was to decrease the dustiness of coated seeds using plasma pre-treatment. The optimization process of plasma treatment parameters for individual seed species consisted of choosing a suitable exposure time (20 s, 60 s) and airflow (10 L/min, 15 L/min). The plasma made the seeds' surface more hydrophilic; therefore, better agrochemicals adhesion was achieved on the seeds' surface. Wettability improvement was demonstrated via water uptake of seeds and apparent contact angle change. Ambient air plasma at a 15 L/min flow rate was measured using optical emission spectroscopy, and the values of vibrational (3000 K) and rotational (347 K) temperatures were obtained from spectra simulation. The surface temperature of the MSDBD ceramics plate was measured with a thermal camera for different gas flow rates and constant input power of 30 W because the temperature is crucial parameter for seed treatment. The surface morphology was not affected due to plasma treatment, even for a longer exposure time. A significant decrease in dustiness measured according to the Heubach method was achieved for pea (57.1%) and parsley (41.4%) seeds. A lower decrease in dustiness was registered in the case of wheat (14.6%) and maize (17%) seeds. The results showed that MSDBD plasma generated in the air at optimized conditions is able to decrease the coated seed dustiness regardless of seed type and size, while seeds germination and surface coverage percentage remained unchanged.

The Multi-hollow Surface Dielectric Barrier Discharge (MSDBD) generated in ambient air at atmospheric pressure was used to treat maize, pea, wheat and parsley seeds. Plasma exposure was applied as a pre-treatment before the seeds coating with agrochemicals. The aim of this study was to decrease the dustiness of coated seeds using plasma pre-treatment. The optimization process of plasma treatment parameters for individual seed species consisted of choosing a suitable exposure time (20 s, 60 s) and airflow (10 L/min, 15 L/min). The plasma made the seeds' surface more hydrophilic; therefore, better agrochemicals adhesion was achieved on the seeds' surface. Wettability improvement was demonstrated via water uptake of seeds and apparent contact angle change. Ambient air plasma at a 15 L/min flow rate was measured using optical emission spectroscopy, and the values of vibrational (3000 K) and rotational (347 K) temperatures were obtained from spectra simulation. The surface temperature of the MSDBD ceramics plate was measured with a thermal camera for different gas flow rates and constant input power of 30 W because the temperature is crucial parameter for seed treatment. The surface morphology was not affected due to plasma treatment, even for a longer exposure time. A significant decrease in dustiness measured according to the Heubach method was achieved for pea (57.1%) and parsley (41.4%) seeds. A lower decrease in dustiness was registered in the case of wheat (14.6%) and maize (17%) seeds. The results showed that MSDBD plasma generated in the air at optimized conditions is able to decrease the coated seed dustiness regardless of seed type and size, while seeds germination and surface coverage percentage remained unchanged.

Diffuse coplanar surface barrier discharge (DCSBD) was used to activate the opposite side of the plasma‐exposed linear low‐density polyethylene/polyamide (LLDPE/PA) tubular film of multilayer casing. We determined that conductive metal rubber roller in the DCSBD system allowed the formation of microfilaments perpendicular to the film surface, resulting in improved wettability and adhesion of inner LLDPE side of the tubular film. These findings were supported by increasing the concentration of polar functional groups. Based on these remarkable outcomes obtained after a very short plasma exposure time of 0.5 s, DCSBD roll‐to‐roll system in proper arrangement affords adhesion improvement of the opposite side of the treated film without any material damage, hence can compete with industrial corona in commercial sphere of plasma treatments.

The aim of this work was the wettability improvement of clay‐coated paper by ambient air plasma exposure. Industrial corona with a volume dielectric barrier discharge in cylindrical configuration was used as a plasma source; the exposure times varied from 0.25 up to 5 s. Water contact angle (WCA) measurement and surface free energy (SFE) evaluation were carried out for the estimation of wettability changes. Plasma treatment in the duration of 0.25 s was sufficient to decrease the WCA almost to the half of the original value, which was 76°. SFE of paper has increased by 40%–50% after plasma treatment. Long‐term ageing effect study of treated samples was carried out up to 3 months after the treatment. WCA did not reach the original value even after 3 months, and it was still 20%–30% lower. O/C ratio increased from 0.7 to 1.8 in case of 5‐s plasma treatment, and the new chemical bonds (C=O, O–C=O) were created on the surface.

The paper presents the effects of plasma treatment on agricultural seeds. Cucumber and pepper seeds, widely used in agriculture, were treated using the Diffuse Coplanar Surface Barrier Discharge (DCSBD) at atmospheric pressure in ambient air. The plasma treatment (4 s for pepper, 20 s for cucumber) led to an improvement of germination and germinating power. XPS confirmed chemical changes on the seed surface. The surface morphology of the plasma treated seeds showed no evidence of structural damage. The conclusion is that DCSBD proves to be able to reduce some of the microorganisms and pathogens affecting the seeds. Thanks to their technical simplicity and easy scaling‐up, DCSBD plasma sources open new opportunities for atmospheric pressure plasma application in the agricultural industry.

This paper deals with an optical emission spectroscopy study of a diffuse coplanar surface barrier discharge (DCSBD) in air at atmospheric pressure. The main aim of this study was to verify the areal homogeneity of the generated plasma, which is important for many applications like treatment of nonwoven fabrics, glass, metals, polymers, foils, and so on. Optical emission spectra of DCSBD plasma in air were measured for three different frequencies (15, 30, and 50 kHz) of the applied voltage. Comparison of the calculated rotational and vibrational temperatures was carried out, and areal homogeneity of plasma was proved. Electrical parameters of discharge such as the plasma power using the area of the Lissajous figures and energy transfer efficiency to the discharge were also investigated. The effective thickness of plasma layer as a function of the input power was measured.