Abstract: A polypropylene or polyethylene film or fiber coated with a maleic-acid grafted polypropylene or polyethylene copolymer layer over which is coated a layer of selective polymer. The copolymer securely bonds the selective polymer to the film or fiber. These fibers and films can be used in fluid separation membranes.

Abstract: PVP-coated asymmetric hollow fibers made from SIXEFT.TM.-Durene, a polyimide made from 2,2-bis[3,4-dicarboxyphenyl] hexafluoropropane dianhydride and 2,3,5,6-tetramethylphenylene diamine monomers, and a process for making such fibers. These coated fibers have a separation factor that exceeds 6 for oxygen and nitrogen and a permeance of at least about 10 ppm cc(STP)/(sec cm.sup.2 cm-Hg). A polymer dope comprising SIXEF.TM.-Durene in a solvent system containing N-methyl-2-pyrrolidone ("NMP") and an organic acid such as propionic acid ("PA") is prepared by polymerizing the polyimide monomers in NMP to form a polyamic acid polymer and imidizing this polymer using the acid anhydride. Water released from the polymer in the imidization reaction converts the anhydride to acid. The dope is wet-spun into hollow fibers; the fibers are coagulated in water. The fibers are then evenly coated with PVP, preferably by dipping the fibers in a dilute PVP solution.

Abstract: Asymmetric fluoropolymer hollow fibers having a thin, dense, inner separation layer that is essentially defect-free. In the process of this invention, a fluoropolymer dope is spun into a hollow fiber using a hollow fiber die, a core solvent, preferably comprising water, and a coagulation bath, preferably comprising a water-acetone mixture. Due to solubility and surface tension differences, the outer layer of the fiber does not coagulate quickly enough to form a dense layer, and remains porous, but the core solvent causes the inner surface of the hollow fiber to coagulate into a thin, dense, defect-free layer.

Abstract: Asymmetric hollow fibers of SIXEF.TM.-Durene, a polyimide made from 2,2-bis[3,4-dicarboxyphenyl] hexafluoropropane dianhydride and 2,3,5,6-tetramethylphenylene diamine monomers, and a process for making such fibers. These uncoated fibers have a separation factor that exceeds 4 for oxygen and nitrogen and a permeance of at least about 50 ppm cc(STP)/(sec cm.sup.2 cm-Hg). A polymer dope comprising SIXEF.TM.-Durene in a solvent system containing N-methyl-2-pyrrolidone ("NMP") and an organic acid such as propionic acid ("PA") is prepared by polymerizing the polyimide monomers in NMP to form a polyamic acid polymer and imidizing this polymer using the acid anhydride. Water released from the polymer in the imidization reaction converts the anhydride to the organic acid. The dope is wet-spun into hollow fibers using a core solvent such as PA or glycerine; the fibers are coagulated in water.

Abstract: A breathable water-resistant fabric in which a surface of a fabric material is coated with a microporous layer of ETFE, and a process for making same. An ETFE dope containing a blend of ETFE and a binder polymer is cast or extruded into a film which is subsequently bonded or laminated to the fabric material. The binder is extracted to produce a microporous ETFE layer.

Abstract: A novel method for making a composite separation membrane, and the product of that method. This novel method includes applying one or more perfluoroethers to the surface of a microporous fiber or film made of a polymer such as PAN, and subsequently coating that fiber or film surface with a layer of selective material. This method provides a more permeable composite membrane than would be obtained by coating a fiber or film that had not been pre-wetted with perfluoroether.

Abstract: A process for coating a polypropylene or polyethylene surface with a maleic acid-grafted polypropylene or polyethylene copolymer. In this process, a dope containing the graft copolymer is applied to the polypropylene or polyethylene surface, e.g. by dip coating, at a temperature high enough to keep the copolymer solvated in the dope solvent. The surface is then dried to leave a porous graft polymer coating bonded to the polypropylene or polyethylene. The coated product has superior adhesion characteristics compared to uncoated polypropylene or polyethylene.

Abstract: Asymmetric hollow fibers having a microporous hollow fiber core comprising a polyolefin, e.g. polypropylene, and an asymmetric coating comprising a fluoropolymer, e.g. SIXEF.TM.-Durene. Optionally, the coating may also comprise glycerine which is applied prior to the fluoropolymer. The fibers are coated by wet-spinning, or alternately by dry jet-wet spinning, through a spinning jet in which a fluoropolymer-containing fluid is applied to the outer surface of the fibers as they pass through the jet. The fibers exit the jet into a water bath. If greater selectivity is needed, the fiber later may be coated with an additional layer of a highly selective material, e.g. polyvinyl alcohol, PVP, and the like.

Abstract: Asymmetric hollow fibers comprising a fluoropolymer, and a process for making such fibers. The hollow fibers are useful for making fluid separation membranes, especially gas separation membranes. In one embodiment of the process of this invention, a polymer dope having a viscosity of about 3000 poise or greater is prepared by solvating the polymer in a solvent system containing about 40%-90% N-methyl-2-pyrrolidone and about 60%-10% propionic acid by weight. The dope is dry-jet wet-spun into hollow fibers using a water-NMP core solvent. The fibers are coagulated in methanol. The fibers are then coated with a highly permeable material.

Abstract: A process for coating a polypropylene or polyethylene surface with a maleic acid-grafted polypropylene or polyethylene copolymer, and stretching the surface to increase permeability without damaging the coated surface. In this process, a dope containing the graft copolymer is applied to the polypropylene or polyethylene surface, e.g. by dip coating, at a temperature high enough to keep the copolymer solvated in the dope solvent; the surface is then dried. The permeability of the surface is improved by stretching the surface at least about 50% beyond its original area or length such that when the stretching force is released a residual strain of less than about 11% exists. The stretching operation may be done simultaneously with or subsequent to the coating operation.

Abstract: Novel polyimide blends are formed of polyimide polymers each having moieties derived from dianhydride and diamine comonomers. The miscible blends of the present invention may be formed by selecting polyimide polymers having structurally different dianhydride-derived moieties, as well as structurally different diamine-derived moieties. More specifically, the blends of this invention include at least one polyimide polymer which is a reaction product of 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride, and 2,2-bis(3-aminophenyl) hexafluoropropane; and at least another polyimide polymer which is a reaction product of 2,2-bis(4-aminophenyl) hexafluoropropane and a dianhydride which is at least one selected from the group consisting of pyromellitic dianhydride, bis(3,4-dicarboxyphenyl) ether dianhydride, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

Abstract: A process for producing a polyhalogenated microporous film having a very narrow pore size distribution and good temperature and chemical resistance. The process involves blending a polyhalogenated copolymer with a polyethyloxazoline utilizing a solvent which is a nonsolvent for the polyhalogenated copolymer but a solvent for polyethyloxazoline, forming a film from the blend, drying the film, heating the film to a temperature at or above the melting point of the polyhalogenated copolymer and under conditions such that the microparticulate particles at their points of mutual contact will neck together to form a relatively continuous matrix and extracting the polyethyloxazoline from the film utilizing a solvent for the binder particle to form a microporous film.

Abstract: A process for producing a polyhalogenated microporous film having a very narrow pore size distribution and good temperature and chemical resistance. The process involves blending a polyhalogenated copolymer having a very small particle size with a binder polymer utilizing a solvent which is a nonsolvent for the polyhalogenated copolymer but a solvent for the binder polymer, forming a film from the blend, drying the film, heating the film to a temperature at or above the melting point of the polyhalogenated copolymer and under conditions such that the microparticulate particles at their points of mutual contact will neck together to form a relatively continuous matrix and extracting the binder polymer from the film utilizing a solvent for the binder particle to form a microporous film.

Abstract: Disclosed herein is a process for producing a polyhalogenated microporous film having a very narrow pore size distribution and good temperature and chemical resistance. The process involves blending a polyhalogenated copolymer having a very small particle size with a binder polymer utilizing a solvent which is a nonsolvent for the polyhalogenated copolymer but a solvent for the binder polymer, forming a film from the blend, drying the film, heating the film to a temperature at or above the melting point of the polyhalogenated copolymer and under conditions such that the microparticulate particles at their points of mutual contact will neck together to form a relatively continuous matrix and extracting the binder polymer from the film utilizing a solvent for the binder particle to form a microporous film.

Abstract: A process is disclosed for the production of biaxially oriented liquid crystal films. The process includes:(i) forming an anisotropic dope from a polymerization solution of rigid rod heterocyclic liquid crystalline polymers such as poly{[benzo(1,2-d:4,5-d')bisthiazole-2,6-diyl] 1,4-phenylene}, its cis isomer or mixtures thereof, and poly{[benzo(1,2-d:4,5-d')bisoxazole-2,6-diyl] 1,4-phenylene}, its cis isomer or mixtures thereof, and a solvent such as polyphosphoric acid;(ii) extruding the dope to form a film;(iii) imparting biaxial orientation to the film to increase the transverse strength thereof;(iv) solidifying the biaxially oriented film; and(v) washing the solidified film to remove the solvent. Also disclosed is a liquid crystal film produced by the above process.