Moisture transport properties of a degradable nylon for food packaging applications

Water transport properties of a degradable polyamide to be used for food packaging applications have been analyzed. The polymer under investigation, poly((4,9)-dioxa-1,12-dodecamethylenesebacamide) (sample A), can be envisaged as modified nylon 12/10 (sample B) in which two of the C-C linkages of the backbone have been replaced with two ether linkages. The introduction of ether linkages should enhance the degradability of the polymeric material compared with nylon 12/10, but, in turn, is also expected to increase both macromolecular mobility and hydrophilicity, promoting an increase in water diffusivity and water sorbance compared with nylon 12/10. Water vapour sorption tests were performed at three temperatures (30, 40 and 50°C) and at several water activities on both samples A and B. Water diffusivity and solubility as well as mixing enthalpies and activation energies were evaluated as a function of water concentration and their values related to macromolecular chain modification deriving from the introduction of ether linkages. © 1997 John Wiley & Sons, Ltd.