National Research Council of Canada

Andre Y Tremblay

Oleh Kutowy

Michael D Guiver

Chung M Tam

Oleh Kotowy

Thomas A Tweedle

Molded articles of an aromatic polymer are described having at least a portion of the surface layer of the polymer modified by a heterogeneous reaction of the solid polymer and a reactive solution. The polymer to be treated may contain different repeating units in the said surface layer. The treatment to produce the molded article may comprise casting, injection molding, extending or otherwise shaping the polymer to mold the polymer into a desired shape. The heterogeneous treatment to produce the heterogeneously modified molded article may comprise treating a surface layer of a flat cast sheet in the form of a flat membrane, spirally wound membrane, hollow fiber, or tubular material.

Method of manufacturing a surface layer modified, molded article of

A method of casting porous membranes of polymeric material is provided wherein the membrane has at least one of the following: a more homogeneous active skin layer for separation purposes with a lower molecular weight cut off, a more homogeneous active skin layer with a sharper molecular weight cut off curve, a relatively thinner active skin layer with a relatively greater flux for a given separation of a substance from a solution thereof, and relatively fewer imperfections through the active skin layer. The method comprises casting a layer of a casting solution on to a support, to provide a cast layer of the casting solution thereon with an exposed skin, then progressively submerging the cast layer in a gelation liquid at a relative velocity of at least 15 cm/second, whereby the exposed skin is gently scrubbed with gelation liquid to continuously remove outwardly diffusing solvent therefrom and dissipate exothermic heat, thus causing gelation of at least a stable, more homogeneous active skin layer, with build-up of a solvent boundary layer between the exposed surface of the layer and the gelation liquid minimized.

Method of casting a porous membrane of polymeric material

Reverse osmosis membranes are manufactured by casting a polysulfone casting composition comprising:

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Vanier, Canada

Andre Y Tremblay