Improving surface wettability and adhesion property of polytetrafluoroethylene by atmospheric-pressure ammonia water-mixed plasma treatment

Abstract

Polytetrafluoroethylene (PTFE) has excellent properties and has been widely used in various fields. However, the PTFE surfaces have relatively poor wettability and adhesive property, which restrains their widespread applications. Although atmospheric-pressure plasma jets have been employed to treat the PTFE surfaces, hydrophilization effect and processing efficiency still need to be further improved. In this paper, we propose to add ammonia water into the working gas of the atmospheric-pressure plasma jets to better modify the PTFE surfaces. The influences of ammonia water contents on surface wettability and adhesive property of the PTFE surfaces were investigated by water contact angle (WCA) measurement and peel strength experiments, respectively. When the ammonia water-mixed ratio was 1%, a WCA of ∼19° was obtained after 120 s plasma treatment, which was much lower than that treated by pure helium plasma jet (∼29°) and untreated surface (∼101°). In addition, the adhesive property was also well improved by the ammonia water-mixed plasma jets: peel strength of the sample treated by the ammonia water-mixed plasma jet was respectively 119 N/m and 446 N/m larger than that of the sample treated by pure helium plasma jet and the untreated sample.