Water vapor permeability (WVP) was performed using two different standard methods. According to ASTM E96-00 standard method, WVP was determined gravimetrically. Films with an
exposure area of 38.48 cm2were fixed on test cells containing a desiccant (calcium chloride). Test cells were placed in chamber with controlled temperature (25?C) and RH (50%). After steadystate conditions were reached, weight of test cells was measured every 1 h over 1 day. Water vapor transmission rate (WVTR) was determined using equation