The film moisture equilibrium content at 58% RH was determined
gravimetrically by desiccating the conditioned films at
105 C for 24 h. Three film specimens measuring 4 cm2 were
weighed accurately and placed in beakers with 25 mL of distilled
water and then sealed and gently shaken at 25 C for 24 h. The
solution was then filtered through Whatman No. 1 filter paper to
recover the remaining undissolved film, which was desiccated at
105 C for 24 h. Film solubility was calculated by the equation