Abstract: Hollow synthetic fibers useful in reverse osmosis, ultrafiltration, gas separation and the like, having high hydraulic permeability to the solvent and capable of operation at pressures from 600 psi and up, are prepared by forming a solution of a fiber-forming polymer in a suitable solvent, adding to the solution a second polymer soluble in the solvent but with limited compatibility with the first polymer when their total concentration increases on coagulation, extruding the resulting solution through an orifice equipped for coaxial extrusion so that coagulating fluid within tube flow results, precipitating with a liquid which is miscible with the solvent for the fiber-forming material, is a non-solvent for the first polymer and a solvent for the second, contacting the extruded solution with the precipitating liquid either coaxially through the extrusion device or by passing the extrudate through the precipitating liquid, and finally washing the resulting hollow fiber free of residual solvents and non-solvents

Abstract: A porous film of polytetrafluoroethylene having an accurately controlled pore diameter and a superior pore diameter distribution, and a process for preparing the film.

Abstract: A semipermeable membrane is obtained by casting a cast solution comprising a mixture of a water-insoluble high polymer and a water-soluble high polymer, a mixture of a water-insoluble high polymer and a water-soluble surfactant or a mixture of a water-insoluble high polymer, a water-soluble high polymer and a water-soluble surfactant to form a shaped article, exposing the thus formed shaped article to a plasma to crosslink the surface thereof, and then washing the exposed article with water to remove uncrosslinked water-soluble high polymer or water-soluble surfactant. The membrane can be used for such substance separation methods as reverse osmosis, ultrafiltration and the like.

Abstract: Polymeric sheets having on one or both sides a fabric texture and a network of elongated channels in the interior of the structural framework of the sheet. In one embodiment, the sheets comprise a plurality of interbonded continuous polymeric ribs extending in a direction parallel to the plane of the sheet. The ribs impart a fabric texture to both sides of the sheet and define between them recessed portions on each surface of the sheet. The elongated channels extend throughout the ribs. The open area between the ribs can vary from zero to 60%. In another embodiment, the sheets have an ultra-thin, pinhole-free silicone rubber membrane on one side and a fabric texture on the other side. The sheets are useful as burn coverings where they serve as synthetic temporary replacements for damaged or missing skin.

Abstract: Ceramic foams possessing controlled permeability and uniformity are prepared by the impregnation of an open-celled organic polymer foam material possessing a predetermined permeability and resilience with a aqueous slurry of a thixotropic ceramic composition while shearing said slurry an amount sufficient to maximize said impregnation, and expelling excess slurry from said material by conducting at least two passes of said material through preset rollers to effect a temporary compression ranging from about 50 to 90% for the first pass and 70 to 90% for the second pass. The resulting material is then dried and heated to remove the organic foam component. The foams prepared in accordance with the present invention are useful as filters for molten aluminum.

Abstract: Method of improving the shear strength properties of degraded fibrous/resin composites comprising subjecting the composite article to a vacuum heat treatment. The vacuum heat treatment of the degraded composite article regenerates the bond at the fibrous/resin interface, causing a regain in shear strength. The treatment comprises subjecting the composite to a pressure of about 1 millimeter of mercury at a temperature of 300.degree. F (149.degree. C) for 24 hours.

Abstract: The manufacture of ion-exchanging shaped articles, in particular fibers, fabrics and membranes, by polymerization of the polymerizable monomers of a homogeneous mixture of a polyolefin, a vinylaromatic compound, an aromatic divinyl compound and a solvent of low volatility, converting said mixture to a shaped article, removing the said solvent and introducing ion-exchanging groups into the said shaped article.

Abstract: Polyester polymer is recovered from polyester fibers (in the form of filaments, yarns or fabrics and the like, both dyed and undyed), and used in the production of new undyed fibers, films, and other polymer products through the process of: stripping the dye from the dyed polyester fibers by contacting the fibers with a dye-stripping solvent for polyester polymer at a temperature below which the polyester fibers dissolve and above which the crystalline lattice of the polyester fibers swell so as to release the dye; then removing essentially all of the dye-containing dye-stripping solvent which is not absorbed by the fibers and fabrics; then contacting the wet solvent-laden fibers, possibly containing residual dye, with sufficient addition of a dissolution solvent under dissolution conditions for polyester fibers; thereafter precipitating the polyester out of; and, separating the polyester from the solution.

Abstract: Polyester polymer is recovered from mixed collections of fibers in the form of fibers, filaments, or fabrics (including dyed or undyed fibers other than polyester fibers as well as dyed polyester fibers) and used in the production of new undyed fibers, films and other polymer products through the process of stripping the dye from the polyester fibers by contacting the fabrics with a dye stripping solvent for polyester polymer which is preferably not a solvent for fibers other than polyester fibers at a temperature below which the polyester fibers dissolve and above which the crystalline lattice of the polyester fibers swell so as to release the dye; then removing essentially all of the dye-containing dye-stripping solvent which is not absorbed by the fibers; then contacting the solvent-laden fibers (which may contain residual dye) with sufficient additional solvent under selective dissolution conditions for polyester fibers; then removing the undissolved fibers and any other undissolved impurities from the so

Abstract: Ultrathin membranes for separating substances are obtained by exposing shaped articles comprising a water-soluble polymer or a mixture of a water-soluble polymer and water-insoluble polymer to a plasma of a gas selected from helium, argon, nitrogen, hydrogen, oxygen, carbon monoxide, carbon dioxide, ammonia, a hydrocarbon having 1 to 10 carbon atoms, an epoxide having 2 to 10 carbon atoms, or an alkylamine, or a mixture of these substances to crosslink the surface layer, and then washing the exposed articles with water to remove the unreacted portions. The membrane exhibits outstanding performance characteristics when used in the processes for separating or concentrating substances, such as reverse osmosis, ultrafiltration, and the like.

Abstract: Hollow articles, in particular microballoons, hollow fibers and other shapes, are prepared by dispersing or dissolving a soluble film-forming solid in a core solvent which is normally solid but transformable slowly to gas, shaping the blend while molten, cooling to solidify and slowly removing the solid core material as a gas. The film-forming solid migrates to form a shell having the original core shape and a non-uniform cross-section of an outer skin and an inner sponge lining.

Abstract: A reticular split film comprising transverse, relatively thick, oriented, regularly formed stemfibres and intervening relatively thin, and generally irregularly formed branchfibres, which are biaxially oriented and film-shaped in areas adjacent to the stemfibres and more fibre-shaped over the rest of their length.The structure is produced by embossing (profiling) a film in a biased or perpendicular line pattern, orienting and splitting the thin intervening portions between the thicker striations while shearing the striations relative to one another, and finally orienting the striations.