Analysis of air permeability and moisture permeability of textiles

1. Moisture permeability

The moisture permeability of a fabric refers to the performance of moisture permeating the fabric, also known as water vapor permeability, which is the ability to maintain the thermal balance of heat production and heat dissipation of the human body when the human body is radiated and sweated. It is simply understood that rainwater from the outside cannot enter, and the sweat vapor emitted by the human body is discharged through the pores of the coating and membrane.

There are two test methods for moisture permeability: positive cup and inverted cup

Positive cup method: GB/T 12704.1-2009 "Textiles-Fabric moisture permeability test method Part 1: Moisture absorption method"; GB/T 12704.2-2009 "Textiles-Fabric moisture permeability test method Part 2: Evaporation method Method A".

Inverted cup method: GB/T 12704.2-2009 "Textiles and Fabric Moisture Permeability Test Method Part 2: Evaporation Method Method B".

2. Breathability

The breathability of a fabric refers to the performance of gas molecules passing through the fabric to produce air convection. To put it bluntly, it is the air penetration that can be directly felt in the past. It mainly affects the wearing comfort of the fabric, such as heat insulation, warmth, permeability, Coolness and fabric performance, etc., in outdoor products, it is usually combined with the windproof function, that is, windproof and breathable, in order to ensure the windproof and warmth of the fabric to achieve a certain air permeability to improve wearing comfort. In outdoor textile products, it is feasible to achieve a certain degree of air permeability while blocking the 4-5 level of wind.

Method Air Permeability R (Method Air Permeability): It means the performance of the air through the fabric; under the specified pressure difference condition, measure the air flow rate vertically through a given area of the sample within a certain period of time, and calculate the air permeability. The air flow rate can be measured directly, or it can be calculated by measuring the pressure difference between the two sides of the flow aperture. This is the real breathability!

Test standard: GB/T 5453-1997 "Determination of Air Permeability of Textiles and Fabrics", the air permeability unit is expressed in mm/s or m/s.

Recognition and application of moisture permeability and ventilation function

Functional description is mostly used in the assault clothing category, which means that more sweat and water vapor can pass through the fabric to maintain comfort during exercise.

Windproof and breathable function description is mostly used in soft shell products, which means that by reducing the air permeability of the fabric, the purpose of windproof and warmth is achieved, and the range of air permeability is confirmed to achieve a balance between windproof and comfort.