where WVTR was themeasuredwater vapor transmission rate (g/m2·s)
through a film, L was the mean film thickness (m) and Δp was the
partial water vapor pressure difference (Pa) across the two sides of
the film.
The contact angle of water in air on the film surface was measured
using a CA analyzer (Model Phoenix 150, Surface Electro Optics Co., Ltd.,
Kunpo, Korea) after a water drop of ca. 10 mL was placed on
the surface of the film using a microsyringe.
All the film samples
(3 × 10 cm) were glued on the movable sample stage (black Teflon
coated steel, 7 × 11 cm) leveled horizontally before measurement.
The
CA on both sides of the drop was measured to assume symmetry and
horizontal level.