2.4. Ozonation for increasing surface hydrophilicity
Surface hydrophilization of PPW films by ozonation was conducted
in a volumetric glass reactor with a capacity of 3.0 dm3
by providing 30 cm height and 15 cm diameter (Okuda et al.,
2007). The reactor with ceramic bubble diffuser plate has pore
diameter of 10–16 lm, was arranged at the bottom of a reactor.
An average flow rate of 50 ml/min ozone gas was feed in a reactor
through diffuser produced by an ozone generator (POX-10,
Fuji-electric). Ozonation was applied to the films for 30 min
retention period. The effectiveness of ozonation in terms of
hydrophilicity, contact angle of film surface was measured before
and after ozonation. The contact angle was measured by using Contact
angle meter (CA-XP, Kyowa Interface Science), FAMAS (Face
Measurement & Analysis System).