What is the difference between air permeability and fabric porous structure?

Air permeability and fabric porous structure are related concepts but refer to different aspects of a material's airflow characteristics.

Air permeability is a measure of the ability of a material to allow air to pass through it under a specific pressure differential. It quantifies the ease with which air can flow through the material, indicating its breathability or the resistance it offers to the passage of air. Air permeability is typically expressed in units such as cubic centimeters of air per second (cm³/s) or liters per square meter per second (L/m²/s).

On the other hand, fabric porous structure refers to the arrangement and characteristics of the pores, openings, or void spaces within the fabric structure. Porosity defines the total volume percentage of voids within a material, and it can include various types of spaces, such as open pores, closed cells, or inter-fiber spaces. Fabric porous structure relates to the physical properties of the fabric's construction, including fiber arrangement, yarn type, weave or knit pattern, and any additional treatments or finishes applied.

While air permeability is a quantitative measurement that provides a numerical value indicating how easily air can flow through the material, fabric porous structure describes the physical arrangement and characteristics of the void spaces within the fabric. The fabric porous structure contributes to the overall air permeability of the material, but it is not solely dependent on it. Other factors, such as fabric thickness, density, and surface smoothness, also influence air permeability.

In summary, air permeability focuses on the measurement of airflow through a material, whereas fabric porous structure encompasses the physical arrangement and characteristics of the void spaces within the fabric. Both concepts are important in understanding the breathability and performance of materials, but they represent different aspects of a material's airflow behavior.