The naturally hydrophobic surface of the PTFE hollow fiber membrane makes it ideally suited for a broad range of filtration and contacting applications for organic chemical systems and certain aqueous systems. This inherent low surface energy makes it an ideal system for passing organic liquids or retaining aqueous systems for degassing or distillation. There are, however, applications where one requires the thermal stability, chemical resistance, or chemical inertness of PTFE but with a higher surface energy, or a non-porous surface is required.
By providing surface treatment or modification of the PTFE, an even greater range of applications become possible. Markel is actively pursuing a family of coatings and surface treatments that, when applied to the fiber inner or outer surface, will alter the mass transfer or filtration characteristics of the hollow fiber. These coatings may be non-porous, permeable membranes that facilitate the separation of similar small molecules, the creation of a hydrophilic surface on the pore structure, or bonding chemically reactive sites onto the membrane surface.
Additionally, PTFE hollow fibers serve as excellent support for catalyst particles. The unique nature of the Markel process for producing PTFE hollow fiber enables the wall thickness to be varied independently of pore structure, allowing the designer to create a structure suitable for loading with heterogeneous catalyst systems. The high service temperature of the PTFE membrane and its chemical resistance place it alone among polymeric membranes for these exacting applications.