Abstract
To understand the mechanism of surface processing using an atmospheric-pressure non-equilibrium microwave discharge plasma jet, we used optical emission spectroscopy to measure the vibrational and rotational temperatures of plasma. A microwave (2.45GHz) power supply was used to excite the plasma. The vibrational and rotational temperatures in the plasma were measured at approximately 0.18 eV and 0.22 eV. We also conducted plasma surface processing of polyethylene naphthalate (PEN) film to measure changes in the water contact angle before and after the PEN film was processed and as the rotational temperature of the plasma increased. Analysis of all the results from XPS, and surface free energy as calculated from the contact angle confirms that the improvement in hydrophilic properties of the PEN film surface using the microwave discharge plasma jet were effective, after comparing improvements in the hydrophilic properties of PEN film surface by plasma exposure. We conclude that the hydrophilicity of the polyethylene naphthalate film surface improves as the rotational temperature of the plasma increases.
