What is the working mechanism behind ePTFE membrane vents - Wuxi Sinceriend New Material Technology Co., Ltd.

The working mechanism of expanded Polytetrafluoroethylene (ePTFE) membrane vents leverages the unique physical structure to perform a critical function: allowing free passage of air and gases while acting as an impenetrable barrier to liquids, particulates, and contaminants.
This selective permeability is achieved through a microporous structure and the innate hydrophobic properties of the PTFE polymer. The membrane is created by expanding PTFE through a specialized mechanical process, stretching it into a complex matrix of microscopic fibrils and nodes.
The resulting membrane contains billions of interconnecting, tortuous pores per square centimeter, typically sized between 0.2 to 3.0 micrometers. This pore size physically blocks solid contaminants like dust, dirt, and pollen, as well as larger water droplets.
The inherent hydrophobicity and oleophobicity of PTFE provide the second crucial component. The material's extremely low surface energy causes water and oil molecules to bead up on the surface rather than wetting or wicking through it.
This property, combined with the small pore size, creates a high surface tension barrier that prevents liquid penetration even under moderate pressure, functioning like a fine mesh screen that allows air passage but blocks water.
Pressure equalization occurs as temperature changes cause air inside enclosed spaces to expand or contract. The ePTFE vent provides a dedicated pathway for gas molecules to flow freely through its microporous network, equalizing internal and external pressures almost instantaneously.
This continuous breathing action also helps expel residual moisture vapor trapped inside assemblies, preventing condensation and fogging, operating as a passive, intelligent filter that selectively permits gas exchange while defending against environmental elements.