Abstract: The invention relates to a composite membrane with a porous polymer support layer and a polymer top layer, whereby the porous polymer support layer is of polyacrylonitrile (PAN), polyacrylamide, polyetheretherketone (PEEK), polyetherketone (PEK), polysulfon or polyethersulfon, whereas the polymer top layer is a dense layer comprising polyvinyl chloride with selective water permeability. Preferably the membrane is provided with a porous polyacrilonitril support layer and a polyvinyl chloride top layer. Further the invention comprises the application of such a composite membrane for the dehydration of organic solvents using such a composite membrane.

Abstract: The invention relates to a process for preparing a microporous membrane, starting from a mixture of at least a hydrophobic polymer and a hydrophilic polymer, by dissolving these polymers first in a suitable solvent or mixture of solvents and subsequently by coagulating in a coagulation bath. According to the invention a more or less hydrophilic membrane is prepared by removing the membrane so obtained from the coagulation bath and subsequently by leaching at least a part of the hydrophilic polymer from the matrix, alternatively followed by hydrophobization. Said leaching of the hydrophilic polymer occurs by treatment of the membrane with an oxidizing/hydrolizing agent. The invention furthermore comprises microporous membranes, flat or tubular or in the form of hollow fibers, having a good chemical resistance and good mechanical strength.

Abstract: A prevaporation process characterized by excellent separation efficiency employs a membrane that comprises an elastomeric polymer matrix containing zeolite.

Abstract: Process for the production of a bilayer membrane consisting of a selectively acting nonporous polymer membrane first layer and a microporous membrane second layer, in which a polymer solution intended for the formation of the first layer is brought into contact with one side of the second layer. A larger amount of polymer solution than is necessary for the formation of the first layer is used, and a portion of the solvent is caused to volatilize through the pores of the second layer. The polymer solution is not caused to enter the pores of the second layer. After the first layer has attained the desired thickness, the excess polymer solution is removed. The first layer may be subjected to a drying and/or cross-linking treatment.

Abstract: This invention relates to a process for the preparation of hydrophilic membranes by coagulation of a solution of at least one hydrophobic polymer and at least one hydrophilic polymer in a suitable solvent medium in a coagulation medium. The process according to the invention is characterized in that hydrophilic microfiltration and/or ultrafiltration membranes are prepared by cross-linking the hydrophilic polymer which is present in or on the obtained membrane matrix after the coagulation in an essentially non-swollen state and fixing same as such in or on the polymer matrix. Advantageously the solvents and the undesirable components of the coagulation medium are removed whereby the hydrophilic polymer is converted into an essentially non-swollen state prior to cross-linking. The removal of the undesirable components from the membrane takes place by means of a non-solvent for the hydrophilic polymer according to the invention.

Abstract: This invention relates to a process for the preparation of hydrophilic membranes by coagulation of a solution of at least one hydrophobic polymer and at least one hydrophilic polymer in a suitable solvent medium in a coagulation medium. The process according to the invention is characterized in that hydrophilic microfiltration and/or ultrafiltration membranes are prepared by cross-linking the hydrophilic polymer which is present in or on the obtained membrane matrix after the coagulation in an essentially non-swollen state and fixing same as such in or on the polymer matrix. Advantageously the solvents and the undesirable components of the coagulation medium are removed whereby the hydrophilic polymer is converted into an essentially non-swollen state prior to cross-linking. The removal of the undesirable components from the membrane takes place by means of a non-solvent for the hydrophilic polymer according to the invention.