Abstract
Coated cardboards are emerging as alternatives to plastics in the field of food packaging. Cardboard is a cellulose-based porous material, with very poor barriers to gases and water vapor, which are often required for primary packaging materials and food protection. One method to improve its performance is to coat one or more layers of barrier polymer. The choice of the nature of the polymer is key to achieve specific barrier properties, but other parameters are also at stake, such as the properties of the cardboard supports, the polymer coating weight or the number of coating layers. In this study, the respective roles of cardboard support, coating weight and number of layers on the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) of fatty acid grafted poly(vinyl alcohol) (PVOH) coated cardboards were investigated. Then, a correlation between these parameters and the obtained transmission rates was attempted. Finally, the experimental values were compared to predicted values, using the series resistance model, which conventionally links the OTR and WVTR of a multilayer material to the OTR and WVTR of each layer. The limitations of using such model with coated cardboards were highlighted, and hypotheses regarding the structure/properties relationship of such materials were formulated based on scanning electron microscope images, allowing the examination of the surface of the coated materials