scholarly journals Flexible thermally treated 3D PIM-CD molecular sieve membranes exceeding the upper bound line for propylene/propane separation

2017 ◽  
Vol 5 (9) ◽  
pp. 4583-4595 ◽  
Author(s):  
Jiangtao Liu ◽  
Youchang Xiao ◽  
Tai-Shung Chung
Keyword(s):  
Upper Bound ◽  
Molecular Sieve ◽  
Cross Linking ◽  
Sieve Effect ◽  
Line P ◽  
Thermally Treated

The flexible thermally treated 3D PIM-CD cross-linking networks have narrow gates and better molecular sieve effect for propylene/propane separation exceeding the upper bound line.

Intermolecular Effects: II. Constraints along Network Chains

1997 ◽  
Author(s):  
Burak Erman ◽  
James E. Mark
Keyword(s):  
Free Energy ◽  
Upper Bound ◽  
Cross Linking ◽  
Chain Model ◽  
Free Energies ◽  
Real Situation ◽  
Cross Links ◽  
Rigorous Treatment ◽  
Link Model ◽  
Constraints Model

In the constrained-junction model presented in chapter 3, intermolecular correlations were assumed to suppress the fluctuations of junctions. According to this model, the elastic free energy of a network varies between the free energies of the phantom and the affine networks. In a second group of models, to be introduced here, there is a constraining action of entanglements along the chains that may further contribute to the elastic free energy, as if they were additional (albeit temporary) junctions. Consequently, the upper bound of the elastic free energy of such networks may exceed that of an affine network. Since the entanglements along the chain contour are explicitly taken into account in the models, they are referred to as the constrained-chain models. The idea of constrained-chain theories originates from the trapped-entanglement concept of Langley, and Graessley, stating that some fraction of the entanglements which are present in the bulk polymer before cross-linking become permanently trapped by the cross-linking and act as additional cross-links. These trapped entanglements, unlike the chemical cross-links, have some freedom, and the two chains forming the entanglement may slide relative to one other. The two chains may therefore be regarded as being attached to each other by means of a fictitious “slip-link,” as is illustrated schematically in figure 4.1. The entangled system of chains representing the real situation is shown in part (a), and the representation of two entangled chains in this system joined together by a sliplink is shown in part (b). The slip-link may move along the chains by a distance a, which is inversely proportional to the severity of the entanglements. A model based on this picture of slip-links was first proposed by Graessley, and a more rigorous treatment of the slip-link model was given by Ball et al. and subsequently simplified by Edwards and Vilgis; section 4.1 describes this latter treatment in detail. In section 4.2, we present the extension of the Flory constrained junction model to the constrained-chain model by including the effects of constraints along chains, following Erman and Monnerie. One of the newest approaches, the diffused-constraints model, is then described briefly in section 4.3.

scholarly journals A Comparison of Isosteric and Differential Heats of Gas Adsorption on Microporous Active Carbons

1994 ◽  
Vol 11 (1) ◽  
pp. 15-29 ◽  
Author(s):  
J.K. Garbacz ◽  
G. Rychlicki ◽  
A.P. Terzyk
Keyword(s):  
Experimental Data ◽  
Molecular Sieve ◽  
Gas Adsorption ◽  
Active Carbons ◽  
Sieve Effect

A comparison of both isosteric and differential heats of single gas adsorption on microporous active carbons has been undertaken. The experimental data obtained indicate strong differences between the analysed quantities for the studied adsorbents. It is deduced from thermodynamical considerations that a molecular sieve effect is responsible for these differences.

Molecular sieve effect of the blood-aqueous barrier

1975 ◽  
Vol 21 (3) ◽  
pp. 289-297 ◽  
Author(s):  
J.P. Dernouchamps ◽  
J.F. Heremans
Keyword(s):  
Molecular Sieve ◽  
Sieve Effect ◽  
Blood Aqueous Barrier

Molecular sieve effect in the hydration of olefins on zeolites

1985 ◽  
Vol 34 (8) ◽  
pp. 1784-1784
Author(s):  
L. N. Tolkacheva ◽  
R. V. Dmitriev ◽  
L. A. Novikova ◽  
S. Z. Taits ◽  
Kh. M. Minachev
Keyword(s):  
Molecular Sieve ◽  
Sieve Effect
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