Gas Permeation Properties

Linear Low Density Polyethylene. Films from linear low density polyethylene (LLDPE) resias have 75% higher tensile strength, 50% higher elongation-to-break strength, and a slightly higher but broader heat-seal initiation temperature than do films from LDPE. Impact and puncture resistance are also improved over LDPE. Water-vapor and gas-permeation properties are similar to those of LDPE films. 

In our research, three chemical modification approaches were investigated bromination, sulfonylation, and acylation on the aromatic ring. The specific objective of this paper is to present the chemical modification on the PPO backbone by a variety of electrophilic substitution reactions and to examine the features that distinguish modified PPO from unmodified PPO with respect to gas permeation properties, polymer solubility and thermal behavior. 

The solution properties of the brominated PPO derivatives were similar to those of the parent polymer. The gas permeation properties of PPO and PPO containing between 6.5% to 100% Br groups per repeat unit are summarized in Table I. 

Chemical modifications of PPO by electrophilic substitution of the aromatic backbone provided a variety of new structures with improved gas permeation characteristics. It was found that the substitution degree, main chain rigidity, the bulkiness and flexibility of the side chains and the polarity of the side chains are major parameters controlling the gas permeation properties of the polymer membrane. The broad range of solvents available for the modified structures enhances the possibility of facile preparation of PPO based membrane systems for use in gas separations. 

Sakai, T., Takenaka, H., Wakabayashi, N., Kawami, Y. and Torikai, E. 1985. Gas permeation properties of solid polymer electrolyte (SPE) membranes. Journal of... 

Hietala, S., Skou, E. and Sundhokn, F. 1999. Gas permeation properties of radiation-grafted and sulfonated poly-(vinylidene fluoride) membranes. Polymer 40 5567-5573. 

Zhou, W, Watari, T., Kita, H. and Okamoto, K. 2002. Gas permeation properties of flexible pyrolytic membranes from sulfonated polyimides. Chemistry Letters 5 534-535. 

Gas permeation properties of ethylene vinyl acetate-silica nanocomposite membranes./. Membr. Sd., 322 (2), 423 28. 

N. Tanihara, H. Shimazaki, Y. Hirayama, N. Nakanishi, T. Yoshinaga and Y. Kusuki, Gas Permeation Properties of Asymmetric Carbon Hollow Fiber Membranes Prepared from Asymmetric Polymer Hollow Fibers, 7. Membr. Sci. 160, 179 (1999). 

K-i Okamoto, Fuji M, Okamyo S et al (1995) Gas permeation properties of poly(ether imide) segmented copolymers. Macromolecules 28(20) 6950-6956... 

Pinnau I, He Z, and Morisato A. S3mthesis and gas permeation properties of poly(dialkylacetylenes) containing isopropyl-terminated side-chains. J. Membr. Sci. 2004 241 363-369. 

Pinnau I and He Z. Pure- and mixed-gas permeation properties of polydimethylsiloxane for hydrocarbon/methane and hydro-carbon/hydrogen separation. J Membr Sci 2004 244 227-233. 

Kusakabe K, Kuroda T, Uchino K, Hasegawa Y, and Morooka S. Gas permeation properties of ion-exchanged faujasite-type zeolite membranes AIChE J 1999 45(6) 1220-1226. 

Secondly the membrane is formed by the filtration and retention of a colloidal zeolite precursor. The characteristics of the pore structure of these membranes is described here, together with some of the gas permeation properties. 

Some gas permeation properties of these membranes are reported in Refs. [42,48]. Molecular sieving properties have not been observed [48] contrary to results obtained by the Lange. This might be due to a combination of the larger roughness of the commercial supports, the somewhat smaller hydrolysis ratio H20/Si (r = 5 instead of 6.4 used by de Lange), and the smaller layer thickness which all lead to an increased risk of defects in the layer. The ageing and dr dng conditions were also different. 

A model of the structure of the fine crystalline layers is given in Fig. 8.30. Based on gas permeation properties, it is hypothesised that grain boundaries between the small crystals play a beneficial role on the transport properties of the layer. The intrinsic gas permeation values of the small crystals seem to be smaller than that of the large ones reported by Geus. 

Tanihara, N.H., Shimazaki, Y., Hirayama, S., et al. (1999). Gas permeation properties of asymmetric carbon hollow fiber membranes prepared from asymmetric polyamide hollow fiber. J. Membrane Sci., 160(2), 179—86. 

Nehlsen S., Hunte T, Muller J., Gas permeation properties of plasma polymerized thin film siloxane-type membranes for temperatures up to 350°C, J. Med Screen., 106, 1-7, 1995. 

B. A. McCool, Y.S. Lin, Nanostructured thin palladium-silver membranes Effects of grain size on gas permeation properties,/. Mater. Sci. 2001, 36, 3221-3227. 

H.-J. Lee, D.-P. Kim, H. Suda, and K. Haraya. Gas permeation properties for the post-oxidized polyphenylene oxide (PPG) derived carbon membranes Effect of the oxidation temperature. / Membr. ScL, 282(l-2) 82-88, October 2006. 

A. C. Lua and J. Su. Effects of carbonisation on pore evolution and gas permeation properties of carbon membranes from kapton(r) polyimide. Carbon, 44(14) 2964-2972, November 2006. 

Kusakabe, K. Kuroda, T. Uchino. K. Hasegawa, Y. Morooka. S. Gas permeation properties of ion-exchanged Faujasite-type zeolite membranes. AIChE J. 1999. 45. 1220-1226. 

Takata. Y. Tsuru, T. Yoshioka, T. Asaeda. M. Gas permeation properties of MFI zeolite membranes prepared by the secondary growth of colloidal silicalite and application to the methylation of toluene. Microporous Meso-porous Mater. 2002, 54, 257-268. 

Poly[l-(trimethylsilyl)-l-propyne] (PMSP) is a typical glassy polymer at room temperature that was first syndiesized by Masuda and Higashimura in the 1980 s (1). Recently, membranologists have studied their gas permeation properties. The PMSP membrane has the highest gas permeability of all polymeric membranes. Therefore, this polymer is expected to have potential utiliQ in industrial applications such as the separation of oxygen and nitrogen from air. 

The drying conditions influenced the gas permeation properties of the PMSP membranes therefore, the membranes were dried under vacuum according to the same method as previously described (6). 

K. Matsumoto, P. Xu, Gas permeation properties of hexaflu-oro aromatic polyimides. Journal of Applied Polymer Science 1993,47, 1961. 

T. Sakai, H. Takenaka, N. Wakabayashi, Y. Kawami, and E. Torikai, Gas Permeation Properties of Solid Pol5mer Electrolyte (Spe) Membranes, Journal of the Electrochemical Society, 132, 1328 (1985). 

Table 7.5 Mixed gas-permeation properties of PTMSP and PMP. Feed 2% butane in methane, feed pressure 10 bar, permeate pressure atmospheric, temperature 25 °C. From I. Pinnau et al. In Polymer Membranes for Gas and Vapor Separation, ACS Symposium Series 733 (1999), 56-67.

The inventors caU this polymer class polymers of intrinsic microporosity (PIMs) , because their porosity arises as a consequence of the molecular structure and is not generated solely through processing. The PIMs can exhibit analogous behavior to that of conventional materials, but, in addition, may be processed into convenient forms for use as membranes [291]. The gas-permeation properties of membranes formed from PIM-1 were investigated at the GKSS... 

A. Morisato, 1. PiNNAU, Synthesis and gas-permeation properties of poly(4-methyl-2-pentyne). Journal of Membrane Science 121 (1996) 243. 

Lee D, Zhang L, Oyamaa ST, Niue S, Saraf RF (2004) Synthesis, characterization, and gas permeation properties of a hydrogen permeable silica membrane supported on porous alumina. J Membr Sci 231 117-126... 

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