Water vapour barrier properties of biodegradable film

Biodegradable polymers are rarely used in food packaging applications due to their low moisture barrier properties. In order to improve this point, it is important to understand the influence of chemical structure and processing conditions on their barrier properties. Biodegradable polyesters, were investigated by means of water permeability, crystallinity level, thermal and mechanical tests. When the chemical structure changes, despite a crystallinity level decrease, water vapour permeability values diminish because the amorphous phase characteristics improve. Two different process conditions were investigated: aluminium deposition and co-extrusion; both lead to permeability enhancement.