Today, we introduce a commonly used material parameter known as gas transmission rate.
In simple terms, it describes how gas passes through a film material under certain conditions.

When discussing this parameter, a few basic points are helpful to understand.

First, gas transmission rate is related to material thickness. For the same type of material, a thicker sample usually allows less gas to pass through over the same period of time.

Second, gas transmission rate is influenced by factors such as thickness and test pressure. In comparison, the gas permeability coefficient is generally used to describe an inherent property of the material itself and is typically discussed independently of sample thickness.

Third, gas transmission rate is commonly determined using a pressure difference method. In this approach, a stable pressure difference is maintained on both sides of the sample, and changes on the lower-pressure side are recorded over time using sensing devices. The results are then used to obtain a gas transmission value. This method is described in standards such as GB/T 1038 and is widely used in routine material studies.

In practical applications, materials with lower gas transmission values are often selected for uses such as food packaging, moisture-sensitive products, and air-retention structures. Materials with higher gas transmission values may be chosen for applications where air exchange is desired, such as breathable textiles.

Overall, gas transmission rate helps describe how materials behave in different usage situations and supports material selection for various products