Solvent vapour permeation

Generally all plastic films are water-repellent (water-resistant). Various degrees of barrier are offered against water vapour permeation, gases (organic and inorganic), oils, solvents, aromatics, preservatives, etc. All films, if free of pinholes, provide a barrier to moulds, bacteria, etc., i.e. are a hygiene barrier. 

Vapour permeation is used for the separation of a mixture of saturated vapours, and is often combined W ith distillation, to separate solvents from exhaust air streams, especially in degassing operations such as resin production. 

MEMBRANE VAPOUR PERMEATION SOLVENT STRIPPING OF ARTIFICIAL SYNTHETIC POLYISOPRENE LATICES AND OTHER LATICES... 

The composition at the permeate-phase interface depends on the partial pressure and saturation vapour pressure of the component. Solvent composition within the membrane may vary considerably between the feed and permeate sides interface in pervaporation. By lowering the pressure at the permeate side, very low concentrations can be achieved while the solvent concentration on the feed-side can be up to 90 per cent by mass. Thus, in contrast to reverse osmosis, where such differences are not observed in practice, the modelling of material transport in pervaporation must take into account the concentration dependence of the diffusion coefficients. 

Pervaporation have been considered an interesting alternative process for the current industrial options for aroma recovery, distillation, partial condensation, solvent extraction, adsorption, or a combination thereof. It is considered a basic unit operation with significant potential for the solution of various environmental and energetic processes (moderate temperatures). This separation process is based on a selective transport through a dense membrane (polymeric or ceramic) associated with a recovery of the permeate from the vapour phase. A feed liquid mixture contacts one side of a membrane the permeate is removed as a vapour from the other side. Transport through... 

The use of fibre-reinforced composites has grown dramatically in the last few years. In many applications these materials may come into contact with water (vapour or liquid) as well as organic solvents. Consequently, it is very important to understand how the permeation properties of the polymers used can affect the mechanical properties of the composites. 

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