Moisture permeability of fabric
May 16, 2019
Definition: The ability of moisture to pass through the fabric, also known as water vapor permeability, referred to as moisture permeability or vapor permeability.
Moisture permeability mechanism: The essence of fabric moisture permeability is the gas phase transfer of water. When there is a certain relative humidity difference on both sides of the fabric, the water vapor is transmitted from the side with high relative humidity to the side with low relative humidity.
Measurements and indicators: using hygroscopic or evaporative tests, measured by perspective or moisture permeability
Factors affecting moisture vapor permeability:
1. Influence of fabric structure and composition
There are three main ways for water vapor to pass through the fabric: one is the diffusion of water vapor through the micropores in the fabric, the other is that the fiber itself absorbs moisture and escapes on the side where the water vapor pressure is low, and the third is that a large amount of water vapor molecules will produce condensation. However, the expansion by capillary action and the low vapor pressure produces more evaporation.
2. Atmospheric conditions
When the relative humidity of the air increases, the resistance to evaporation of the fabric to the human body increases, and the moisture permeability of the fabric decreases.
The environmental climate has a great influence on the heat and moisture transferability of the fabric. When the wind speed is high, the insulation value of the garment fabric decreases with the increase of the wind speed, and the moisture permeability increases with the increase of the wind speed, indicating that the increase of the airflow speed is beneficial to the transmission of the garment fabric. Heat and moisture.
Relationship with clothing comfort: If the water vapor evaporated on the surface of the skin cannot be removed through the fabric in time, a high-humidity heat zone will be formed between the skin and the fabric, making people feel stuffy.
