2.3.4. Water vapor permeability (Kw)
Film water vapor permeabilities (Kw) were determined in
appropriate diffusion cells (Saranto´ poulos et al., 2002), using
a relative humidity gradient of 2–75%. Water vapor permeability
was determined using Eq. (3).
Kw ¼
Wd
Spsðaw1 aw2Þ
(3)
where d is the average film thickness, S is the film permeation area
(0.005 m2), aw1 (75%) is the water activity in the chamber, aw2 (2%)
is the water activity inside the cell, ps is the water vapor pressure at
the experimental system temperature (25 C) and W ¼ G/t (g of
water/hour) was calculated using the linear regression of mass
variation over time, under steady state permeation condition.
2.3.4. Water vapor permeability (Kw)Film water vapor permeabilities (Kw) were determined inappropriate diffusion cells (Saranto´ poulos et al., 2002), usinga relative humidity gradient of 2–75%. Water vapor permeabilitywas determined using Eq. (3).Kw ¼WdSpsðaw1 aw2Þ(3)where d is the average film thickness, S is the film permeation area(0.005 m2), aw1 (75%) is the water activity in the chamber, aw2 (2%)is the water activity inside the cell, ps is the water vapor pressure atthe experimental system temperature (25 C) and W ¼ G/t (g ofwater/hour) was calculated using the linear regression of massvariation over time, under steady state permeation condition.
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