Aug 20, 2020
Water vapor permeability (WVP) is a measure of the passage of water vapor through a membrane. It is the rate of water vapor transmission per unit area per unit of vapor pressure differential under test conditions.
The higher the value of the permeability of the material, the more rapidly vapour can pass through it. Vapour permeability is the rate at which vapour passes through a material.
Water vapor permeability (WVP) is the most studied property of biodegradable films, mainly because of the important role of water in spoilage reactions, keeping food fresh, crisp, or preventing dehydration.
The most widely used method to measure the water vapor permeability is ASTM Standard Test Method E96, also well-known as the cup method. This method is based on calculating the WVP of a sample by gravimetry.
