Abstract: The invention concerns a method for producing a nanofiltration membrane. At least one face (30) of a porous membrane (3) is put in the presence of a grafting composition comprising at least one monomer grafted by radical polymerisation and at least one crosslinking agent, that is however free from photoinitiator, and of light radiation capable of forming free radicals during a predetermined period adapted so as to obtain nanofiltration properties. The invention also extends to the nanofiltration membrane obtained in this way of which the properties may be precisely predetermined and which resist ageing.

Abstract: A process for the production of a porous organic material, in particular an organic semi-permeable membrane, provided with a plurality of separate passageways, comprising dissolving a polymer in a solvent, using a drawplate comprising needles having a shape conjugate with that of the passageways and external dimensions comprising between 0.7 and 1.2 times those of said passageways and an extrusion orifice of a conjugate fome to that of the extrudate and of internal dimensions comprising between 0.8 and 1.2 times those of said extrudate, injecting around the needles a solution having a viscosity greater than 500 millipascal-second, introducing into the interior of the conduits of the drawplate a centering fluid which is a non-solvent with respect to the polymer and able to precipitate the polymeric solution, causing the extrudate to travel from the output of the drawplate a distance da in a gaseous atmosphere which is non-precipitating with respect to the polymeric solution such that 500.times.e<da<0.

Abstract: A process for the production of a porous organic material, in particular a semi-permeable membrane, comprising a plurality of separate passageways, including dissolving a polymer in a solvent, using a drawplate having needles of a shape conjugate with those of the passageways and of external dimensions between 0.7 and 1.2 times those of the passageways and an extrusion orifice of a shape conjugate those of the extrudate and of internal dimensions comprising between 0.8 and 1.2 times those of the extrudate, injecting around the needles a solution having a viscosity greater than 500 mPa.s and introducing a centering fluid into the interior of these needles, recovering the extrudate at the output of the drawplate in a precipitating medium in such a manner that the extrudate travels in the medium a distance such that 800.times.

Abstract: A method of fabricating a tube plate for a hollow fiber separator apparatus, from a set of hollow fibers with an end of the set being embedded in a resin, wherein the set of hollow fibers is subdivided into a plurality of elementary bundles, at least a first end of each elementary fiber is enclosed in a reinforcing element and the first ends are stuck together using a resin in order to form a reinforced tube plate. The invention also relates to tube plates and to hollow fiber separator devices.

Abstract: Non symmetrical hollow fibres presenting a relatively dense layer (`skin`) (H) of a very small thickness (<1 .mu.m) at their outer periphery, which is bound to a so called `open` structure of which the porosity increases in the direction to the inner face; said porous structure comprises microvoids (1) shaped like elongate fingers open to the inside. The invention also relates to the method for obtaining such a symmetrical hollow fibres by known spinning techniques by dry-wet process, by adding to the solution for spinning the polymer in the solvent at least one particular additive and by adding a particular fluid through the hole of the extruded product. Finally, the invention aims at applying the hollow fibres in question to various fields and particularly in ultra-filtration or micro-filtration, in dialysis, reverse osmosis, in gas permeation or pervaporation or they may also be used as supports for liquid membranes.