Abstract: A semipermeable membrane is described which comprises a homogeneously miscible polymer blend of an aromatic polyamide and polyvinylpyrrolidone. The aromatic polyamide is in particular formed of recurrent units of the formula I: ##STR1## wherein E.sup.1 and E.sup.2 are identical or different and are selected from the groupings ##STR2## --AR.sup.1 --, and --AR.sup.1 --X--AR.sup.2,where AR.sup.1 and Ar.sup.2 are the same or different 1,2-phenylene, 1,3-phenylene or 1,4-phenylene groups which may be substituted by (C.sub.1 -C.sub.6)-alkyl, (C.sub.1 -C.sub.6)-alkoxy, --CF.sub.3 or halogen and X denotesa) a direct bond or one of the following divalent groups: --O--, --C(CF.sub.3).sub.2 --, --SO.sub.2 --, --C(R.sup.1).sub.2 --, with R.sup.1 being hydrogen, (C.sub.1 -C.sub.6)-alkyl or fluoroalkyl having from 1 to 4 carbon atoms in the alkyl group or--Z--AR.sup.1 --Z--, where Z is one of the groups --O-- and --C(CH.sub.3).sub.2 or--O--Ar.sup.1 --Y--Ar.sup.2 --O--, where Y has the meaning given under Xa) above.

Abstract: A semipermeable membrane of polyether ketones is disclosed. It contains a polymer possesssing the following recurring units: ##STR1## where x denotes ##STR2## with R.sub.1, R.sub.2, R.sub.3 and R.sub.4 being identical to or different from one another and denoting H, alkyl, aryl, oxyaryl, NO.sub.2, CN, NR.sub.2 or halogen, andZ being one of the groupings --O--, --S--, --CH.sub.2 --, --CF.sub.2 --, ##STR3## --SO.sub.

Abstract: A process for preparing an asymmetrical macroporous membrane from a polymer solution comprised as the dissolved portion fraction a polymeric mixture comprised of about 5-70% by weight of polyvinylpyrrolidone having a molecular weight of .gtoreq.100,000 Dalton and about 95-30% by weight of a polymer selected from the group consisting of polysulfone, a polyether sulfone, and an aromatic or araliphatic polyamide, said weight being relative to the total weight of the dissolved polymeric fraction, by action of a coagulating liquid, wherein the coagulation is effected under conditions such that skin formation, asymmetrical port formation and retention of the polyvinylpyrrolidone are achieved, recovering the asymmetrical macroporous membrane comprising the polymeric mixture.

Abstract: Disclosed are asymmetrical macroporous membranes based on a synthetic polymer comprising a polymeric mixture of 5 to 70% by weight polyvinylpyrrolidone having a molecular weight .gtoreq.100,000 Dalton and 95 to 30% by weight of a polymer selected from a group consisting of a polysulfone, a polyether sulfone and an aromatic or araliphatic polyamide, each of the percentages by weight being relative to the total weight of the polymeric mixture. The membrane has a water absorbency of at least 11% by weight of water, relative to its total weight, at 100% relative humidity and 25.degree. C. Also disclosed is a process for preparation of the membranes.

Abstract: The present invention relates to molded articles of an open-cell structure, containing a copolymer which is comprised of copolymerized, fluorinated olefin, copolymerized vinyl acetate and optionally copolymerized olefin, the acetate groups of the copolymer being optionally saponified into OH groups. The molded articles possess an inherent latent structural convertibility and have effective pores of a diameter in the range from 0.002 to 10 .mu.m. The invention further includes processes for the preparation of the specified molded articles and processes for converting their structure. The invention also relates to several uses of molded articles according to the invention.