where mo and mt are the weight of the samples before and after
immersion, respectively.
Water vapor uptake ratio (WVUR) was determined following
the method of Tunc and others (2007).
Squared samples (25 × 50 mm) were first dried in a vacuum drier at 60 ◦C for 1 d.
After being weighed using a 4-digit electronic balance, the samples were stored
over K2SO4 saturated salt (98% RH) at 25 ◦C for a predetermined
time.
The WVUR was calculated as: