Fig. 1. Experimental device for DBD surface modification

Fig. 2. Voltage, current and instantaneous power of DBD excited by AC power supply

Fig. 3. Voltage, current and instantaneous power of DBD excited by nanosecond pulse power supply

Fig. 4. Variation curve of average power and energy efficiency of DBD excited by different power supplies with water vapor content

Fig. 5. Lighting emission pictures of DBD excited by two power supplies under different water vapor content

Fig. 6. Emission spectra of DBD excited by different power supplies

Fig. 7. Variation of the intensity of OH spectra with water vapor content for different power supplies

Fig. 8. Water contact angle of PP material under different treatment time

Fig. 9. Surface morphology of polypropylene measured by AFM (3D and 2D)

Fig. 10. FTIR spectra of untreated polypropylene material

Fig. 11. FTIR spectra of polypropylene material under different conditions