Determination of Water Vapor Transmission Rate and Water Vapor Permeability in Flexible Films

This conference paper evaluates the water vapor transmission rate (WVTR) and water vapor permeability of flexible packaging films used in food applications. Five polymeric materials were investigated: polyester, PVC, metallized polypropylene, low-density polyethylene (LDPE), and high-density polyethylene (HDPE). Water vapor barrier properties were determined using the ASTM E96-90 gravimetric method under controlled humidity conditions. Film samples were evaluated in duplicate, and water vapor transmission rates were calculated from mass variation over time, followed by determination of water vapor permeability. Among the materials tested, metallized polypropylene exhibited the lowest water vapor transmission rate and therefore the highest barrier performance, while PVC showed the highest transmission rate. Polyester also demonstrated comparatively strong resistance to water vapor transfer. The results highlight how differences in packaging material properties can influence moisture protection and, consequently, food quality and shelf-life preservation.