Influence of Pulse Rising Time on Plasma Irradiation Effect

Abstract

Plasma irradiation experiments were performed under atmospheric pressure in N2 using two pulse power supplies with different pulse rising times, and the irradiation effect on a polycarbonate surface was examined. When investigating the effect of the pulse rising time on the contact angle, it was found that a short irradiation time of 5 s had a significant influence on the contact angle and that a larger decrease in the contact angle was observed with a fast-rising pulse. On the Basis of optical emission spectrometry of the plasma and a surface free energy analysis, the decrease in the contact angle was considered to be the result of the introduction of a large amount of hydrophilic groups on the surface. On the other hand, the effect of the plasma irradiation on the contact angle was not very different with a longer irradiation time of 5 min.