Porex Corporation is a global market leader in porous materials development, manufacturing, and innovation.
Discovered in the 1930’s, PTFE is a well-known material that has excellent temperature, environmental and chemical resistance, and is used in many electrical, industrial, medical and consumer applications. PTFE also has very low surface energy making it very slippery and naturally hydrophobic. In the late 1960’s, a process was developed to stretch PTFE film (known as expanded PTFE or ePTFE) to the point it becomes porous, thus allowing passage of small molecules such as air and water vapor, yet still repelling polar liquids such as water. Expanded PTFE, often fabric supported as part of a layered composite, found applications in areas such as in rain resistant breathable clothing and many industrial venting applications.
The POREX Virtek™ PTFE process begins as a powder with a tight particle size distribution. The powder then goes through a forming and sintering process to create a bulk microporous structure. This process fuses the particles together while creating voids in our proprietary process. The size of the voids can be predetermined by varying the morphology of the starting powders. The resulting structure is then cut to a precisely controlled thickness.
The process results in a robust, durable, design-flexible omni-directional material with long-term value advantages that does not require a supporting layer (scrim). It can be easily handled manually or by high-speed equipment with minimal damage concern and can be applied using various techniques such as adhesive backing, vibrational or heat welding, or insert molding.
To better illustrate the differences between ePTFE and POREX Virtek™ microporous PTFE, below is a microscopic image of a typical unsupported ePTFE membrane. The membrane forms a network of interconnected nodes and fibrils which provides the structure for gases to pass. One of the limitations of this network is the tensile pull of the fibrils to the nodes which can change with temperature and pressure, thus the ePTFE membrane is often part of a multi-layered structure that supports and protects it.
Below are typical microscopic images of POREX Virtek™ microporous sintered PTFE. Structure differences are apparent as absent are the nodes and fibrils and visible is a network of well-controlled particles all bonded to their neighbors.
This structure provides a very robust 3 dimensional membrane that experiences very little change with temperature or pressure, and requires no supporting layers.
With the differing structures come different features and benefits….
Visit Gerry's Engineering Corner to learn more about the robustness and easy handling of POREX VirtekTM PTFE.