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.

Abstract: The phospholes and P-functional phospholes correspond to the general formula: ##STR1## in which: R.sub.1 and R.sub.2 are identical or different and represent hydrogen or a lower alkyl group of C.sub.1 to C.sub.4 such as a methyl group, and R.sub.3 represents an aryl group (such as --C.sub.6 H.sub.5) or a substituted aryl group (such as --CH.sub.2 C.sub.6 H.sub.5) or an alkyl group (such as --CH.sub.3, --C.sub.2 H.sub.5, --C.sub.3 H.sub.7 to C.sub.12 H.sub.25) or a --(CH.sub.2).sub.n Z group where Z denotes a function of the --COO-alkyl type (such as --COOC.sub.2 H.sub.5), --CH, --CO-aryl (such as --COC.sub.6 H.sub.5), --CO-alkyl (such as --COCH.sub.3) or --OH and n.gtoreq.1.

Abstract: The invention relates to a semi-permeable membrane for lead acid batteries. The membrane has a microporous structure comprising a first polymer and a second polymer closely mixed together, the first polymer being poly (2-hydroxyethylmethacrylate), known as reticulated poly HEMA, characterized by the fact that the second polymer comprises one polymer or a mixture of several different polymers chosen from among polyoxyethylene glycol, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, copolymers of acrylic and methacrylic acid, polyacrylates and polymethacrylates of alkyl, and the copolymers of the acrylates and methacrylates of alkyls.

Abstract: The invention relates to a semi-permeable membrane for a lead-acid battery. The membrane has a microporous structure comprising a first polymer and a second polymer intimately mixed together, and is characterized by the fact that the first polymer is chosen from among the following polymers: polyacrylic acid, polymethacrylic acid, a copolymer with a high proportion of acrylic or methacrylic acid, a mixture of these polymers, the average molecular weight of these polymers lying between 10,000 and a few millions and preferably between 50,000 and one million, the second polymer being soluble in water.