PTFE, membrane technology

Products/technologies MultiScreen Assay Plate System is a 96-well plate configuration with membrane filters individually sealed to the bottom of each well. This allows for incubation and flow-through washes. These plates are now available with PTFE membranes and a plastic base that is solvent-resistant. 

Microflow nebulizer coupled with membrane desolvation An example of this is the Aridus system from Cetac Technologies. The aerosol from the nebulizer is either self-aspirated or pumped into a heated PEA spray chamber (up to 110°C) to maintain the sample in a vapor phase. The sample vapor then enters a heated PTFE membrane desolvation unit, where a coun-... 

The final principles of back-pulse filter technology are the nature and properties of the GORE-TEX membrane. The membrane is composed of expanded polytetra-fluoroethylene, or e-PTFE. The membrane traces its roots to the invention of e-PTFE by Robert W. Gore in 1969. Since that time, e-PTFE has found application in many areas including medical devices, electronics, fabrics and fuel cells to name a few. In the filtration area, e-PTFE is used in the form of a membrane to capture and remove particles from both gaseous and liquid streams. 

While several niche applications for OD have been identified, the commercial acceptance of the technology has been hampered by the nonavailability of a suitable membrane-membrane module combination. Fluoropolymer membranes, such as PTFE and PVDF, have been shown to provide superior flux performance, but are still unavailable in hollow fiber form with a suitable thickness for use in OD applications. The inherently low flux of OD requires fhaf membranepacking density be maximized for effective operation, and hence the available flat-sheet form of perfluoro-carbon membranes is unsuitable for commercial use. Four-port hollow fiber modules that provide excellent fluid dynamics are currently available, but only low-flux polypropylene membranes are utilized. 

The membrane in a membrane fuel cell fulfils several important functions as stated in the introduction. Nafion was the first commercially available membrane, which lead to a breakthrough in fuel cell technology. Today, various companies are engaged in membrane development especially for this purpose, aiming at improved material properties. The goals are less sensitivity towards elevated temperature and dry operation, better chemical and mechanical stability and reduced methanol crossover for DMFC operation. A significant improvement of the mechanical stability was achieved by incorporation of a PTFE porous sheet as mechanical support for the membrane material [13,14]. 

M.M. Teoh, T.-S. Chung, Membrane distihation with hydro-phobic macrovoidfree PVDF-PTFE hohow fiber membranes. Separation and Purification Technology 2009, 66, 229-236. 

The molecular structure of a conventional polymer used for a PFSA membrane is shown in Fig. 1. Membranes registered as Nafion (DuPont), Flemion , (Asahi Glass), and Aciplex (Asahi Chemical) have been commercialized for brine electrolysis and they are used in the form of alkali metal salt. Figure 4 shows a schematic illustration of a membrane for chlor-alkali electrolysis. The PFSA layer is laminated with a thin perfluorocarboxylic acid layer, and both sides of the composite membrane are hydrophilized to avoid the sticking of evolved hydrogen and chlorine. The membrane is reinforced with PTFE cloth. The technology was applied to PEFC membranes with thickness of over 50 xm [14]. 

Yoshida M, Kimura Y, Chen J, Asano M, Maekawa Y (2009) Preparation of PTFE-based fuel cell membranes by combining latent track formation technology with graft polymerization. 

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