Membrane reinforcement

Table 10-1 Hot Asphalt Membranes Reinforced with Glass Fabric...

Table IV indicates the degree of elongation found for membranes reinforced with PTFE fabric.

Table IV. Elongation of Perfluoro Ionomer Membrane Reinforced with PTFE Fabric.

Fig. 1.4 (a) Generalized membrane structure. Hydrophobic heads of amphipathic molecules are shown in black and hydrophilic tails as wavy lines. Membrane reinforcers are shown as boxes and can be likened to nails spanning half the membrane (e.g.sterols and hopanoids) or rivets spanning the entire membrane (e.g. carotenoids). Where they are absent, in archaebacterial thermophiles, the amphipathic molecules span the entire membrane and act as struts , (b) Possible steps in the self-assembly of primitive membranes (M2+ are metal ions). 

Polar carotenoids rigidify the lipidmembrane in its fluid state by restrictions to different kind of molecular motions oflipid. This type ofinteraction influences mechanical properties of the membrane (reinforcement) and is consistent with the idea of a xanthophyll pigment as a molecular rivet to the membrane. 

FIGURE 21.29 FER comparison of non-CS membrane reinforced CS membrane and XL membrane during an automotive load cycling test. (DuPont, 2002.)... 

Abstract This article outlines some history of and recent progress in perfluorinated membranes for polymer electrolyte fuel cells (PEFCs). The structure, properties, synthesis, degradation problems, technology for high temperature membranes, reinforcement technology, and characterization methods of perfluorosulfonic acid (PFSA) membranes are reviewed. 

Various reviews on PFSA technology development have been published and detailed explanations of the individual items are available from those materials. In this chapter, the fundamentals of PFSA membranes, the requirements for advanced PEFCs, development trends for high temperature membranes, reinforcement technology, membranes for DMFC, and topics on analysis technology are reviewed. 

Referring to microbial cellulose applications, bacterial nanocellulose has proven to be a remarkably versatile biomaterial with use in paper products, electronics, acoustic membranes, reinforcement of composite materials, membrane filters, hydraulic fracturing fluids, edible food packaging films, and due to its unique nanostructure and properties, in numerous medical and tissue-engineered applications (tissue-engineered constructs, wound healing devices, etc). 

FIGURE 4.8.42. A Tensile strength vs area of membrane reinforcement (taking the tensile strength of unreinforced membrane to be one). B Electric resistance vs area of membrane reinforcement (taking the electric resistance of unreinforced membrane to be one). In Leno weave, the vertical strands are double twisted and the horizontal strands are single twisted. (With permission from E.I. duPont de Nemours Co, Inc.)... 

The dimension of a membrane used in a PEM fuel cell changes with the relative humidity (RH). Repeated swell-shrink cyeling of the MEA poses significant mechanical stress on the membrane, which can cause it to wear down or tear apart quickly. A membrane with little dimensional change offers better mechanical stability, and this is typically achieved by membrane reinforcement. 

Figure 17. SEM micrographs for the PVA/PAA composite polymer membrane reinforced with sulfonated PP/PE separator (a) top surface and (b) cross-section.

A reinforced double-membrane sensor has been fabricated to improve the protective feature of the membrane and to enlarge the linear current response of oxygen. The inner current-determining Teflon film (25 m thick) is covered by an outer silicone membrane reinforced by a thin stainless steel mesh. This arrangement obviously increases the mass transfer impedance of oxygen. Thus, the current signal (at the cathode of the effective surface S) decreases according to... 

Finally, an asbestos membrane reinforced with polyphenylene sulfide was used in an electrolysis cell, though not as an electrode but as a cell compartment separator. The cell was used to produce hydrogen by the electrolysis of alkaline solutions at high temperatures. For this application, polyphenylene sulfide is impregnated into an asbestos card, then sulfonated with sulfur trioxide (Eq. (10)). It was found necessary... 

PIPE Membrane reinforcement Gas Diffusion layer coating Electrochemical resistance Inertness Hydrophobicity... 

As discussed in Sect. 12.1, the polymer membrane reinforced with a high mechanical strength... 

As the performance of the membrane is the most important element in the economy of a membrane cell, many refinements have been made in membrane manufacturing. To reduce the current screening due to fabrics, membranes reinforced with dispersed... 

Yun SH, Woo JJ, Seo SJ, Wu LA, Wu D, Xu TW, Moon SH (2011) Sidfonated poly(2,6-dimethyl-l,4-phenylene oxide) (SPPO) electrolyte membranes reinforced by electrospun nanofiber porous substrates for fuel cells. J Membr Sci 367(1—2) 296-305... 

Perfluorinated membranes reinforced with woven PTFE, such as Nafion 324 or Nafion 417, are used in many industrial electrochemical processes. Unfortunately, the relatively coarse weave of the woven PTFE reinforcement results in membranes that are much too thick for high electrochemical performance. Some non-woven PTFE/perfluorinated ionomer composite membranes have been formulated for ion transport studies and for investigation of other properties relevant to chlor-alkaU and fuel cell applications. Advancements in materials and processing technology have resulted in the introduction of PTFE/perfluorinated ionomer composite membranes claimed by Gore and Associates, Inc. under the Gore Select trademark. Most types of ion exchange membranes contain some type of reinforcement because they are weak and tend to swell substantially as they incorporate a solvent onto their structure. This reinforcement can be a macro reinforcement or a micro reinforcement . 

FIGURE 16.4 SEM images of the cross section of PES membranes enhanced with WSj nanoparticles (0.25% [WSj/PES ratio]). (Reprinted from J. Coll. Inteif. ScL, 396, Lin, J.Y. et al.. Novel PES membrane reinforced by nano-WS2 with ultra-low concentration for enhanced permselectivity and improved fouling resistance, 120-128, Copyright 2013, with permission of Elsevier.)... 

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