December 9, 2021

Analysis of influencing factors of moisture permeability test

At present, in addition to the beauty and fashion requirements of textile fabrics, people also have more and more requirements for functionality, such as thermal comfort, wind resistance, breathability, moisture permeability and waterproofness, warmth retention, etc., which measure the comfort of clothing An important indicator of performance is the moisture permeability of the fabric, that is, the ability of the fabric to transfer the body's natural emission of water vapor to the external environment. It is measured by the amount of test water vapor passing through the fabric sample.


So what exactly is vapour permeability?

Vapour permeability is a material's ability to allow a vapour (such as water vapour or, indeed any gas) to pass through it. To be more precise it is a measure of how much vapour is transmitted through a material (or compound object) under a given set of circumstances. The higher the value of the permeability of the material, the more rapidly vapour can pass through it. Vapour permeability is the rate at which vapour passes through a material.


Test method for Water Vapor permeability Tester:

1. Equipment and reagents used

Fabric moisture permeability tester (with circulating airflow speed: 0.3-0.5m/s), desiccant (need to dry 3 hours before use), distilled water.

2. Test principle:

The principle of the moisture permeability test is to use a moisture-permeable cup with a desiccant or distilled water, and seal the fabric sample, place the moisture-permeable cup assembly in a specified temperature and humidity sealed environment, according to the weight of the moisture-permeable cup assembly within a certain period of time Calculate the moisture vapor transmission rate.


Analysis of influencing factors of moisture permeability test:

1. Influence of wind speed on moisture permeability

The wind speed of the hygrometer directly affects the experimental data, and the large wind speed can increase the amount of water evaporation. For different kinds of fabrics, the wind speed has different effects on the experimental data.

2. Influence of calcium chloride on moisture permeability in hygroscopic method

Since calcium chloride is hydroscopically absorbent, the water of crystallization may not be completely removed in the process of repeated use, and the hygroscopic effect will decline, resulting in deviation. Therefore, it is recommended to dry calcium chloride at high temperature (260 degrees).

3. The influence of distilled water on the moisture permeability in the evaporation method

We know that there are two temperatures to choose from in the test requirements, one is 23 degrees Celsius and the other is 38 degrees Celsius. Before the test, try to keep the temperature of distilled water consistent with the test temperature. The higher the water temperature, the greater the evaporation of water.

4. The influence of the test balance time on the test results in the distillation method

In the same environment, after the test is balanced for 0.5 hour and 1 hour, and the test time is 2 hours, the test results will be different due to different fabric styles. Therefore, it is recommended that the test balance time be 1 hour.

5. The influence of the test surface orientation of the sample on the test.

The orientation of the test fabric also has a great influence on the test results, especially in different manufacturing structures, such as coating, the degree of influence is also different.

fabric moisture permeability test chamber.jpg

With the great R&D strength of products and great production capability, GESTER has two classic fabric moisture permeability tester.

A. ASTM E96 Fabric Water-vapour Transmission Tester GT-C28

Fabric water vapor permeable tester To test the water vapour transmision of various fabric (moisture permeable fabric included) and non-woven fabric such as bat wool, space cotton, sportswear fabric etc.

transmission tester.jpg

B. Water Vapor Permeability & Absorption Tester GT-KC55

Water vapour machine To determine the coefficient of water vapor absorption on leather and non-leather upper. The equipment is basically composed by six stainless steel cups that are inserted in plastic base which maintain them in vertical position.

fabric moisture permeability tester.jpg

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