Evaluation of moisture absorption and quick drying properties of textiles

There are many moisture-absorbent and quick-drying clothing on the market now, so what exactly are moisture-absorbent and quick-drying textiles?

Different countries have different evaluation indicators and requirements. my country’s GB/T 21655.1-2008 “Evaluation of Hygroscopic and Quick-Drying Properties of Textiles – Part 1 Single Combination Test Method” has clear regulations on hygroscopic and quick-drying products: Evaluate the products according to the following table For moisture absorption and quick-drying properties, if all indicators of the product before washing and after washing for 5 times meet the requirements, it can be evaluated as a moisture-absorbing and quick-drying product. If it only meets the requirements of hygroscopicity, it is a hygroscopic product. If it only meets the requirements of quick-drying, it is a hygroscopic product. Quick drying product.

Project		Knitted products	Woven products
Hygroscopicity	Water absorption rate/%	≥200	≥100
	Dripping water diffusion time/s	≤3	≤5
	Wicking height/mm	≥100	≥90
Quick drying	Evaporation rate/(g/h)	≥0.18	≥0.18
Quick drying	Moisture permeability/[g/(m2·d)]	≥10000	≥8000
Note: The wicking height is assessed in the warp (longitudinal) or weft (horizontal) direction, whichever is greater

What is the significance of these five indicators in GB/T 21655.1-2008, and why can they characterize the moisture absorption and perspiration properties of textiles?

Water absorption rate: refers to the percentage of the water absorbed by the sample to the original mass of the sample when the sample is completely soaked in water and taken out until there is no dripping water.

Dripdiffusion time: When water is dropped on a sample, the time required from when the water droplet contacts the sample to when it completely diffuses and penetrates into the fabric.

Evaporation rate: When a certain amount of water is dropped on a sample and then suspended in a standard atmosphere to evaporate naturally, the evaporation mass per unit time in the linear interval on the time-evaporation curve.

Wicking height: A measure of the capillary effect of the test material, that is, when one end of the vertically suspended textile material is soaked with water, the water passes through the capillary action and reaches the height along the upper body of the textile material within a certain period of time.

Water-vapour transmission rate: The mass of water vapor vertically passing through the unit area of the sample within the specified time under the specified temperature and humidity conditions on both sides of the sample.

In the standard, the fabric’s water absorption rate, dripping diffusion time and wicking height are used to characterize the fabric’s adsorption capacity for liquid sweat, and the fabric’s water evaporation rate and moisture permeability in a specified air state are used to characterize the fabric’s speed in the liquid sweat state. Dry.

How are these five indicators tested?

Take the samples before washing and after washing 5 times.

Water absorption: Take 5 samples with a size of 10cm × 10cm and completely soak them in water for 5 minutes. After taking them out, hang them until the samples no longer drip. Calculate the mass percentage of the water absorbed by the samples and the dry cloth. Take the average of 5 times.

Dripping water diffusion time: Take 5 samples with dimensions of 10cm × 10cm, adjust the humidity and balance under standard atmospheric conditions, lay the samples flat, and test the reverse side (the side close to the skin). The dropper mouth should not be more than 1cm away from the cloth surface. Drop 0.2 mL of water onto the sample, and record the time it takes for the water droplet to contact the sample surface until it is completely diffused (no specular reflection). Take the average of 5 times.

Evaporation rate: Drop 0.2 mL of water onto the sample, hang the sample naturally flat and vertically in the standard atmosphere, and weigh the mass every 5 minutes until the change rate of the mass measured twice in a row does not exceed 1%. Calculate the average evaporation rate of the 5 samples respectively.

Wicking height: According to FZ/T 01071, take 3 samples each in the warp and weft directions, record the minimum value of the wicking height at 30 minutes, and calculate the average value of the 3 samples in each direction.

Moisture permeability: According to GB/T 12704.1 moisture absorption method. Place the moisture-permeable cup containing the desiccant and sealed with the sample fabric in a sealed environment with a temperature of 38°C ± 2°C and a relative humidity of 90% ± 2%. Calculate the moisture permeability amount based on the mass change of the moisture-permeable cup within a certain period of time. Calculate the average of 3 samples.