Sorption and Permeation of Allyl Isothiocyanate Vapor in Nylon 6,6 Film as Affected by Relative Humidity

Sorption and permeation of allyl isothiocyanate vapor (AIT, an antimicrobial flavor compound from Cruciferae plants) in nylon 6,6 film were investigated in this study. AIT sorption by the dry nylon film was low (=0.5%, w/w), but increased to a maximum =3.5% as relative humidity (RH) increased. Above 70% RH, the decrease in AIT solubility was presumably caused by the competitive sorption of water. In contrast, AIT permeability increased exponentially with RH due to the plasticization effect of water upon the polymer. A synergistic Tg depression effect was observed when film samples were exposed to water/AIT vapors simultaneously. FTIR studies indicated that water sorption enhanced hydrogen bonding to the C = 0 sites, but weakened the N-H groups.