14 Oct 2020

Porous PTFE (polytetrafluoroethylene) is a high-performance material used in various applications where durability and reliability are crucial. This versatile material exhibits excellent liquid and dust repellence while allowing air to flow omnidirectionally through it. Its unique composition makes it ideal for protection vents commonly used by the packaging, electrical/automotive, and medical industries.

There are two types of porous PTFE: expanded PTFE (or ePTFE), and sintered PTFE (or sPTFE). PorVent® products use POREX sintered PTFE.

The difference – expanded PTFE vs. sintered PTFE

While the purpose of both types of PTFE is to offer a breathable liquid barrier, here is how they differ:

EM image of ePTFE:

EM image of sintered PTFE: POREX Virtek™ sintered PTFE

Sintered PTFE is a durable and robust material. Unlike ePTFE, it will not break down or alter its properties when touched. Think of ePTFE material as a tissue. It’s easy to wrinkle, and the more you handle it, the more likely it is to get damaged. 

Since ePTFE material is fragile, it often requires support. As a result, many expanded PTFE films used in protective vents are laminated to fabric to minimize damage. In contrast, sintered PTFE does not need this additional support, which means the membrane is pure PTFE and offers all the advantages that PTFE has without compromise. 

In general, the more open structure of ePTFE allows for higher flow rates. However, the fragile nature of the material means that when handled, airflow drops dramatically. Tests show that airflow in a sintered PTFE vent remains unaffected even with rough handling.  

Water repellence
PTFE repels water intrinsically, but ePTFE and sintered PTFE handle water differently. When water meets ePTFE, it beads up and can be wicked away, but some of the water often sticks to the film. The remaining liquid could pose a problem; it can be sucked into an enclosure or leak out of the packaging. When water meets sintered PTFE, it beads up and can be wicked away, but no water droplets are left behind, and as a result, provide superior product protection. 

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