High-permeability polymers

On the other hand, if PVC particles were dispersed in a matrix of a highly permeable polymer like EVA, we may assume that after a suffi-... 

One setback for the production of thin-film composite membranes and integrally skinned asymmetric membranes with separating layer thickness of less than 0.2 pm is the defects. A thin coating of a highly permeable polymer can help eliminate the defects. Surface coatings are also applicable in improving the fouling resistance of membranes for UF or NF applications (44). 

Because silicone rubber is a highly permeable polymer, the gas... 

Grinevich Y, Staramiikova L, Yampolskii Y, Gringolts M, Finkelshtein E. Solubility controlled permeation of hydrocarbons in novel highly permeable polymers. J Membr Sci 2011 378(l-2) 250-256. 

Dense homogeneous polymer membranes are usually prepared (i) from solution by solvent evaporation only or (ii) by extrusion of the melted polymer. However, dense homogeneous membranes only have a practical meaning when made of highly permeable polymers such as silicone. Usually the permeant flow across the membrane is quite low, since a minimal thickness is required to give the membrane mechanical stability. Most of the presently available membranes are porous or consist of a dense top layer on a porous structure. The preparation of membrane structures with controlled pore size involves several techniques with relatively simple principles, but which are quite tricky. 

The partial pressure of the transported species is maintained constant in the two gas phases separated by the membrane, by virtue of either the velocity of a sweep gas or the volume of closed gas phases. The membranes are generally in the form of a soaked filter oaoer, or of homogeneous solution supported by highly permeable polymer membranes. At one membrane face there is absorption with chemical reaction at the other there is stripping. Steady-state operation is ensured by zero net conversion within the membrane as a whole. 

Permselectivity or separation factors alMi/Ma) = P(Mi)/P(M2) are compared in Table 3.4 for PTMSN and some other high permeability polymers. It is seen that this polymer is more permselective than PTMSP and AF2400 in the most cases. However, the observed... 

A description of high permeability polymers is not complete if the free volume of the material is not considered. In this work, several methods for evaluation of free volume... 

An important event of recent years in membrane science was the discovery of a new phenomena observed when nano-particles are added into (mainly high permeability) polymer matrix references to these pioneer works can be found in chapters of Section II Nanocomposite (Mixed Matrix) Membranes. So it is not surprising that several presentations at ICOM2008 dealt with such systems. Golename et al. (Chapter 6) investigated the Systran that contained perfiuorinated polymers and surface-fiuorinated zeolites as nano-additives. Perfiuorinated polymer AF2400 with nano-additives was also the object... 

H. Ma, C. Burger, B.S. Hsiao, B. Chu, Highly permeable polymer membranes containing directed channels for water purification, ACS Macro Letters 1 (2012) 723—726. 

Yampolskii, Y. P, etal. 1999). Stucfy of High Permeability Polymers by Means of the Spin Probe Technique. Polymer, 40(7), 1745-1752. 

Fried, J. R. (2006). Molecular Simulation of Gas and Vapor Transport in Highly Permeable Polymers. Materials Science of Membranes for Gas and Vapor Separation. 95-136. 

Fried, J. R. Molecular simulation of gas and vapour transport in highly permeable polymers. Mater. Sci. Membranes Gas Vapour Seoarat. 2006, 95-136. 

By this method also, polymer/silica nanocomposites have been fabricated [165,166]. Merkel et al. discovered that the addition of nanometer-sized fumed silica particles to certain high-free volume, glassy polymers could systematically increase gas permeability. Such high-permeability polymers included poly(4-methyl-2-pentyne) (PMP), poly[l-(trimethyl-silyl)-l-propyne] (PTMSP), andpoly(2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole-co-tetrafluoroethylene) [107]. 

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