How to evaluate the breathability performance of waterproof breathable membrane?

1. Water vapor permeability: Water vapor permeability is one of the important indicators for evaluating the breathability performance of waterproof and breathable membranes. Commonly used testing methods are testing according to international standards ASTM E96 or ISO 15496. During the test, the waterproof breathable membrane is covered in an indoor environment saturated with water vapor, and the breathable performance is evaluated by measuring the amount of water vapor passing through within a certain period of time.
2. Gas permeability: In addition to water vapor permeability, the waterproof and breathable membrane must also have a certain degree of ventilation performance. A common test method is to measure it with a gas permeability meter. During the test, the waterproof breathable membrane sample is enclosed in a certain testing device, and the breathable performance is evaluated by the amount of gas flowing through the tested sample within a certain period of time.

3. Pore size and density: The breathability performance of the waterproof breathable membrane is directly related to its pore size and porosity. By observing the surface morphology and cross-sectional structure of the waterproof breathable membrane with a scanning electron microscope or microscope, you can intuitively understand its pore size and pore distribution. At the same time, pore size and porosity can be quantitatively measured using a pore size tester.

4. Hot and humid breathable performance: Waterproof and breathable membranes are usually used in humid environments, so their hot and humid breathable performance is also one of the important evaluation indicators. It can be tested with a moisture-heat moisture vapor permeability meter, which simulates the difference in temperature and humidity between indoors and outdoors, and measures the moisture permeability of the waterproof breathable membrane under certain hot and humid conditions.

5. Mechanical properties: The waterproof and breathable membrane may be subject to certain mechanical effects such as stretching and tearing during use, so its mechanical properties also need to be evaluated. Indicators such as tensile strength and elongation at break can be measured by a tensile tester, and tear strength can be measured by a tear tester.

6. Durability: The durability of the waterproof and breathable membrane directly affects its service life. The durability performance of the waterproof and breathable membrane can be evaluated through environmental aging tests, chemical contact tests, etc. to understand its anti-aging and chemical corrosion resistance in different environments.