Nitrogen permeability

Stannett and Meyers have reported that crystallisation may reduce the nitrogen permeability by 50%. The moisture vapour permeability of the polycarbonate from l,l-bis-(4-hydroxyphenyl)cyclohexane has been quoted by Schneir as being somewhat below half that of the bis-phenol A polymer (1.7, c.f. 3.8 units). 

Analyses of three rock samples from the pay zone show almost pure calcium carbonate (no magnesium) associated with traces of quartz, kao-linite and pyrite. Solubilities in hydrochloric acid range in between 94.6 and 97.5. Nitrogen permeabilities are below 1 mD, except for one... 

Typically, the liquid permeabilities are obtained with water being the permeate and expressed in terms of L/h-m -bar. The gas permeabilities are often expressed in terms of air or nitrogen permeabilities. The retention characteristics can be generally and generically obtained by using some model molecules. The most commonly used model molecules are polyethylene glycol (PEG) polymers which are linear and flexible in nature, and... 

These high-free-volume polymers also have unusual permeability characteristics with mixtures of condensable and noncondensable gases. For example, in the presence of as little as 1200 ppm of a condensable vapor such as the per-fluorocarbon FC-77 (a perfluoro octane-perfluoro decane mixture), the nitrogen permeability of PTMSP is 20 times lower than the pure nitrogen permeability [71], as shown in Figure 2.41. When the condensable vapor is removed from the feed gas the nitrogen permeability rapidly returns to its original value. The best... 

Polymer Oxygen permeability (Barrer) Nitrogen permeability (Barrer) Oxygen/ nitrogen selectivity... 

Gamma alumina membranes have been commercially available for some time. Compared to alpha-alumina membranes, these membranes have a much more limited thermal and hydrothermal resistance. For this reason, Wu et al. [1990b] exposed the membranes to the application temperature of 600 to 640 C in the presence of water vapor for 2 hours prior to applying commercial gamma-alumina membranes with an approximate pore diameter of 4 nm in dehydrogenation of ethylbenzene. It is found that the modified membrane has a higher nitrogen permeability after the exposure. Once... 

Ward and co-workers adapted this technique to the preparation of ultrathin slllcone/polycarbonate membranes and advanced it by spreading the dilute solution first on a limited water surface between two plastic blocks and then moving the blocks apart. This method spreads the polymer solution continuously, reducing the thickness of the film. A nitrogen permeability rate of 8.6 x 10 cm (STP)/cm -s-emHg and an 0 /N selectivity of 2.3 are reported for a 1000 X thin film. 

The nitrogen permeability and porosity (following Boyle s Law method) of 193 plugs, 1.5 inches in diameter, were obtained from representative litho-facies of the Namorado Sandstone, derived from both below and above the oil-water interface. Samples were analysed in a CORELAB porosimeter and permeabilimeter in the petrophysical laboratory of the Petrobras Research Centre. Permeability values were not corrected for Klinkenberg effects. 

Figure 3.5 Effect of preforming conditions on the permeability of filled PTFE compounds.F i (Nitrogen permeability of...

Table II.09. Nitrogen Permeability vs Temperature and Pressure through Ausimont Malar Ethylene Chlorotrifluoroethylene Copolymer...

Nitrogen Permeability (cc/ cm /sec) (ASTMD1434) Not detected < 2x10 (Hydrogen)... 

The L/D ratio might not affect the nitrogen permeability of PLA [134]. The crystallinity effect has also been evaluated for this gas and it seems that the nitrogen permeability coefficient decreases with the increase in the crystallinity degree of PLA [128]. 

Figure 9-33. Selectivity of different polymer membranes to He-N2 separation as a function of nitrogen permeability (n, incm /(cm x atm x s)) (1) polyvinylidenechloride (2,4)polyethylene terephthalafe (3) polyvinylfluoride (5) polyvinylchloride (6) polyamide (7) plasfified polyvinylidene chloride (8) cellulose nitrate (9) polypropylene (lO)fluoroplast (26) (ll)co-polymer of isoprene (74%) and acryl-nitryl (26%) (12, 18, 20) different co-polymers of butadiene and acryl-rritryl (13) polyacrylate (14) polycarbonate (15) polyisobutylene (16) bulyl latex (17) co-polymer of vinyl chloride and vinyl acetate (19, 37) butyl acetate of cellulose (21) polyethylene vinyl acetate (22) polybutadiene (23) special polymer SKI-3 (24) natural latex (25) nitryl silicon latex (26) dimethyl silicon latex (27) special polymer SKS-30 (28) special polymer SKMS-50 (29) special polymer SKMS-30 (30, 34, 35) high-density, medium-densily, and low-density polyethylene (31) polyethylene with 5% soot (32) co-polymer of ethylene (90%) and propylene (10%) (33) co-polymer of ethylene (96.5%) and vinyl acetate (3.5%) (36) triacetate of cellulose (38) acetate cellulose (39) polystyrene.

Figure 9-14. Oxygen and nitrogen permeability coeffieients (/ 02 and Pn2) for the cobalt porphyrin-polymer complex menftrane. The cob

FIGURE 5.19 Evolution of the nitrogen permeability with aging time for a poly(phenylene oxide) fihn at 35°C as a function of film thickness. The Tg of the material is 210 C. (From Huang and Paul [2007b], with permission. Copyright 2007 American Chemical Society.)... 

Fig. 4.21. Nitrogen permeability through UF PSf membranes after argon plasma treatment at 5W. Reprinted from [40] with kind permission from Materials Research, Universidade Federal de Sao Carlos...

Nagai, K., Kanehashi, S., Tabei, S. and Nakagawa, T. 2005. Nitrogen permeability and carbon dioxide solubility in poly(l-trimethylsilyl-l-propyne)-based binary substituted poly acetylene blends. 251(1-2) 101-110. 

Figure 2.5 Dependence of oxygen permeability (O) and nitrogen permeability (A) on time for PIM-1 membrane (state 3, methanol-treated) kept at ambient temperature in air...

The permeation of gases in such a complex structure is very difficult to model due to the lack of information on the phase structures and properties, as well as the complexity of such modelling. Qualitatively, the reduced mobility and the chain orientation in semi-ordered interphases due to the stiff and ordered crystallites would make the permeability smaller. For the Pebax grades with shorter polyether blocks and longer polyamide blocks, the tortuosity of the diffusion path will increase sharply when the polyether and amorphous PA phases become finely divided by the crystalhne phase. Nevertheless, we tried to use the PA phase crystallinity to simulate the CO2 and nitrogen permeabilities in Pebax films with the simple resistance model [35] to estimate the influence of the Pebax structure on the permeability. 

EXAMPLE 13.4-2, Membrane Design for Separation of Air It is desired to determine the membrane area needed to separate an air stream using a membrane 1 mil thick with an oxygen permeability of P = 500 X 10 cm (STP) cmy(s cm cm Hg). An a = 10 for oxygen permeability divided by nitrogen permeability (S6) will be used. 

EVA (ethylene vinyl acetate) is a copolymer which is available in various compositions of ethylene and vinyl acetate. At a content of 50 vinyl acetate or more the crystallinity has been vanished completely. Give qualitatively the nitrogen permeability at room temperature for a copolymer with 10%, 50% and 90% vinyl acetate respectively and indicate the character of the polymer in terms of rubbery and glassy, crystalline and amorphous (The glass transition temperatures of the pure polymers polyethylene and polyvinyl acetate are given in table II - 5). 

The permeability coefficients of nitrogen, oxygen and toluene are 280, 600 and 1.4 10 Barrer. respectively. A composite membrane has been developed for the removal of toluene vapours from air. As sublayer a polyetherimide (PEI) membrane was developed which has been characterized by the nitrogen permeability and the bubble point (bp). Two membranes (A and B) have been developed with the following properties Membrane A = 10 cm. cm 2.s. cniHg, andar(,p = 0.5 jim... 

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