Abstract: A process is provided for fabricating composite membranes by coating a porous substrate with a solution of selective polymer. A reserve of non-solvent medium is incorporated in the substrate pore network which allows the substrate to be successfully coated with a polymer solution formulated in a solvent medium which is also a solvent for the substrate material.

Abstract: Biological materials such as enzymes, proteins and peptides are encapsulated by forming a mixture of the material and an aqueous non-ionic polymer solution, spraying the mixture into a circulating water-immiscible nonsolvent for the polymer at a temperature sufficient to freeze the beads and drying the frozen beads to remove essentially all unbound water such as to provide a water content of about 1-2 weight percent. Suitable non-ionic polymers are poly(vinyl alcohol), polyvinylpyrollidone, dextran and derivatized cellulose. A densification agent such as alumina may be present in the polymer solution to enhance specific gravity of the beads formed. Encapsulated material such as microbes produced by this process provide useful agricultural agents which can be delivered to the market in a dormant state and suitable for delivery to soil or plant leaves. The beads can be applied dry, via a planting or an insecticide box, or wet via a spray nozzle.

Abstract: Asymmetric gas separation membranes of polymeric materials having selective permeation of at least one gas of a gaseous mixture over that of one or more remaining gases of the gaseous mixture, exhibit improved permeation selectivities for the at least one gas when the asymmetric membranes have been contacted on one or both surfaces with an effective amount of a permeation modifier. The permeation modified asymmetric gas separation membrane having an effective amount of permeation modifier added in a non-homogeneous mode and without loss of Tg.

Abstract: Anisotropic hollow fiber membranes comprising polymer of acrylonitrile and styrene are prepared by extruding a solution of a hollow fiber-forming polymer comprising polymer of acrylonitrile and styrene in a liquid carrier through an annular spinnerette to form a hollow fiber precursor, and the hollow fiber precursor is coagulated in a liquid coagulant comprising water to form a hollow fiber membrane. The liquid carrier used in the method comprises N,N-dimethylformamide and preferably contains non-solvent for the polymer of acrylonitrile and styrene. The hollow fiber membranes have a homogeneously-formed thin selective skin on an open cellular support and exhibit high resistance to collapse. The membranes are especially useful for the separation of gases.