Effect of unsaturated fatty acids as oxygen scavengers in polyethylene terephthalate (PET)

The food and packaging industries are interested in approaches to reduce the permeability of oxygen in polyethylene terephthalate (PET) to extend the shelf-life of product. This has led to considerable research in barrier improvement including the use of active scavenger that permanently binds oxygen. The purpose of this work is to investigate the use of renewably sourced unsaturated fatty acids as scavengers to reduce the oxygen permeability in PET. Unsaturated fatty acids were characterized and incorporated within PET as the reactive additive. Utilization of scavenger capacity and kinetics of oxidation are two key parameters that must be considered while selecting a scavenger, Linoleic acid was chosen for further studies. Blended films were prepared PET/Scavenger system (0.1-2% weight %). The effect of addition of unsaturated fatty acid on the thermal, mechanical properties and morphology of PET were investigated and correlated to changes on oxygen transport. The presence of the scavenger were analyzed using end group analysis where an increase in carboxyl end group was determined and NMR confirmed the presence of linoleic acid within PET. The appropriate method to determine molecular weight was also established. The ability of fatty acid to react with oxygen was studied and incorporated into the polymer in the form a blended systems.