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
Résumé
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.