Celgard

Fig. 5. (a) Preparation method and (b) scanning electron micrograph of a typical expanded polypropylene film membrane, ia this case Celgard. 

Fig. 5-12. Separation of d,1-leucine in hollow-fiber membrane extraction using a Al- -dodecyl-l-hydrox-yproline solution in octanol as the enantioselective extraction liquid. The modules used were 32 cm long and contained 96 Celgard X-20 polypropylene fibers [57].

Better mechanical stability can be expected from irradiated polyethylene or mi-croporous polypropylene ( Celgard ) membranes, but these account for increased electrical resistance values. 

Very different microporous separators for alkaline batteries are included in Table 16. The very thin (-25 ftm) films of stretched polypropylene ( Celgard ) are generally employed in combination with... 

Brand name Celgard 3401 Celgard 3501 PowerSep Sintered PVC... 

Hoechst Celanese Corp. Tonen Corp. Asahi Chemical Industries Mitsubishi Ube Industries Ltd. Pall RAI Celgard membranes made of polypropylene, polyethylene, and combinations Setela membranes made of polyethylene HiPore membranes made of polyethylene Exepol membranes made of polyethylene Polypropylene membranes Polyethylene membranes... 

Separators made by the dry process are available from Hoechst Celanese Corporation and Ube. The Celgard microporous... 

Figure 2. Scanning electron micrographs of surfaces of microporous membranes made by wet and dry processes. (a) Setela microporous membrane (net process) (b) Celgard microporous membrane (dry process).

Dasgupta and Jacobs [29] patented a concept of using a gel layer in combination with a microporous membrane. The gel layer acts as an adhesive bridge between separator and electrodes, just as in the flat pack Zn/MnC cell [30], The microporous membrane (for example, Celgard membrane) provides excellent mechanical... 

The key properties of separators are summarized in Table 2. Table 3 gives some typical values for Celgard membranes. Currently, 25 im is the most widely... 

Table 3. Typical properties of some Celgard microporous membranes. ...

The hot-ER test refers to measuring the impedance of a separator while the temperature is linearly increased this technique was first used by Laman et al. [5]. Figure 4 shows actual measurements for some Celgard membranes [20], The single-layer materials exhibit a sharp rise in impedance near their respective melting points the impedance goes back down after a maximum value has been reached. 

Figure 5. Thermal-mechanical analysis of Celgard microporous membranes.

The simulated short-circuit test was developed to characterize the response of the separator to a short circuit without the complications of battery electrodes. The separator was spirally wound between lithium foils and placed in an AA-size can. To avoid lithium dendrite formation, an alternating voltage was applied to the cell. The cell current and can temperature were monitored. Figure 6 shows the behavior of Celgard membranes. 

Figure 6. Simulated short-circuit of Celgard mi-croporous membrnes.

Celgard LLC markets Hoechst Celanese modular membrane technology (Liqui-Cel ) to remove both oxygen and carbon dioxide from boiler MU water and FW. 

Celgard. Liqui-Cel Extra-Flow Membrane Contactors. Technical literature. Celgard, Inc., USA, 2000. 

Stretched Polymers MF membranes may be made by stretching (Fig. 20-68). Semicrystalline polymers, if stretched perpendicular to the axis of crystallite orientation, may fracture in such a way as to make reproducible microchannels. Best known are Goretex produced from Teflon , and Celgard produced from polyolefin. Stretched polymers have unusually large fractions of open space, giving them very high fluxes in the microfiltration of gases, for example. Most such materials are very hydrophobic. 

Ethyl laurate-water Pore size = 0.2 fim, Product name Celgard 2400, Hoechst 116... 

Coin-type cells (size CR2032, Hohsen Co.) with a lithium foil counter electrode (FMC Corporation) and a polypropylene separator (Celgard 3501) were assembled inside a helium-filled glovebox (<5ppm, H20 and 02). Laboratory made cell fixtures were also used for the HPPC test at room temperature. 

Figure 5. Specific discharge capacity of tin electrode without annealing. Current collector -tungsten. Testing mode C/5. Counter electrode - lithium foil. Separators 1 layer of unwoven polypropylene (Mogilev, Belarus) + 1 layer of Celgard - triangles 2 layers of unwoven polypropylene (Mogilev, Belarus) - dots.

High-power Li-ion cells with a LiNio.8Coo.15Alo.05O2 cathode, a synthetic graphite anode, 1.2 M LiPF6 + ethylene carbonate + ethyl-methyl carbonate (EC/EMC) electrolyte, and a Celgard 2300 separator, were... 

Encouraged by the X-ray and contact angle results, we performed some preliminary gas-permeation measurements. Here, a self-supporting film is required and only the longer block copolymers were used. Fluoro-PSB-II and Fluoro-triblock were coated on porous Celgard 2400 membranes the measurements were taken at room temperature at a driving pressure of 5 bars. Since no absolute polymer layer thickness has been determined, only relative values of the permeability are given (Table 10.6). In the case of the separation of C02 from... 

Table 10.6. Data for Gas Penneation Measurements on Porous Celgard 2400 Membranes Coated with Thin Films of Fluoro-PSB-II and Fluoro-Trihlock"... 

Celgard, LLC, 13800 South Lakes Dr., Charlotte, North Carolina 28273... 

Corresponding author. E-mail pankajarora celgard.com. Telephone 704 587 8478. Fax 704 588 7393... 

---