Testing Water Vapor Transmission Rates for Flexible Barrier Materials Including Metalized Structures

As new materials with increased barrier properties are developed, the instruments and test methods used for measuring the barrier properties must be modified. Metalized structures are a perfect example. Many challenges arise when measuring the water vapor transmission rate of metalized films, from erratic data to flaking of the metalization. Additionally, no ASTM method exists for determining the water vapor transmission rate of flexible pouches. This paper reviews methods for analyzing the water vapor transmission rates of metalized structures, both flat films and flexible packages