Abstract: Copolyamide desalination membranes formed by interfacial polymerization on a microporous support are disclosed. The copolyamide is formed by copolymerization of m-phenylene diamine with cyclohexane-1,3,5-tricarbonyl chloride and any of isophthaloyl chloride, terephthaloyl chloride, or cyclohexane dicarbonyl chlorides wherein the average functionality of the acyl chlorides is from 2.20 to 2.40.

Abstract: Copolyamide desalination membranes formed by interfacial polymerization on a microporous support are disclosed. The copolyamide is formed by copolymerization of m-phenylene diamine with cyclohexane-1,3,5-tricarbonyl chloride and any of isophthaloyl chloride, terephthaloyl chloride, alkylene diacyl chlorides containing 4 to 12 carbon atoms, cyclohexane dicarbonyl chlorides and mixtures thereof wherein the average functionality of the acyl chlorides is from 2.20 to 2.80.

Abstract: A multistage process for preparing interfacially polymerized polyamide reverse osmosis membranes on a microporous support is disclosed. The process involves applying a solution containing from 1 to 10 wt % of an aromatic diamine having 1 or 2 aromatic rings and 2 to 3 amino groups in a first solvent to the microporous substrate. Then a solution of an aromatic or cyclophatic acyl chloride having 1 or 2 rings and 2.2 to 4 acyl chloride groups in a solvent immiscible with the first solvent is applied to the microporous substrate. Then a solution of different acyl chlorides is applied to the substrate. The acyl chlorides in this second solution can have 2 to 4 acyl chloride groups attached to an aliphatic group of 6 to 12 carbon atoms or an aromatic or cycloaliphatic group having 1 or 2 rings and containing 8 to 14 carbon atoms. Also suitable for the second treatment are bis chloroformates.

Abstract: A multilayer membrane for performing reverse osmosis is disclosed. The membrane comprises a porous support and interfacially polymerized thereon a superposed layer of poly meta-phenylene tetrahydrofuran-2,3,4,5-tetracarboxamide in which up to 50 mole % of the tetrahydrofuran-2,3,4,5-tetracarboxamide units have been replaced with isophthalamide or terephthalamide units. The preferred material for forming the support is a polysulfone.

Abstract: A treatment process for treating an interfacially polymerized polyaramide on a microporous support reverse osmosis membrane. The treatment involves immersing the membrane in an aqueous solution containing 5 to 25 weight percent of an alcohol having 1-5 carbon atoms for 15 minutes to two hours at a pressure of 50 to 100 psi. Optionally, the membrane can be treated with a surfactant.

Abstract: A multilayer membrane for performing reverse osmosis is disclosed. The membrane comprises a porous support and a layer formed of poly meta-phenylene cyclohexane-1,3,5-tricarboxamide. The preferred material for forming the support is a polysulfone.

Abstract: Composite reverse osmosis membranes are disclosed wherein a microporous support layer has superposed thereon an interfacially polymerized aromatic copolyamide. The aromatic copolyamide is derived from meta-phenylene diamine and, based on polymerized acid chloride present, 10 to 80% by weight repeating units derived from trimesoyl chloride, from 90 to 15% by weight repeating units derived from cyclohexane-1,3,5-tricarbonyl chloride and up to 40% by weight, repeating units derived from isophthaloyl chloride, terephthaloyl chloride or mixtures thereof. The membranes exhibit improved flux over similar membranes based on trimesoyl chloride while retaining similar salt rejection ability. The membranes containing the diacids exhibit improved flux over similar membranes based on the two triacid chlorides while retaining similar salt rejection ability.

Abstract: A casting solution of polyaramide in N,N-dimethylacetamide containing about 10 to 60% by wt. MgCl.sub.2, based on polyaramide, and a process for making such casting solution, are provided. An asymmetric permselective membrane and process for making such membrane from the casting solution are also provided. Such membrane has excellent performance characteristics in a reverse osmosis process for purifying salt water.

Abstract: In the preparation of permselective membranes by extracting a solvent-cast membrane with non-solvent, the improvement of quenching with a polar liquid before extraction.

Abstract: A process is disclosed for producing a composite reverse osmosis membrane. The process involves forming a porous polysulfone membrane from a solution of polysulfone followed by quenching the polysulfone membrane in an aqueous solution of m-phenylenediamine followed by reacting the m-phenylenediamine on the polysulfone membrane with either trimesoyl chloride or cyclohexane-1,3,5-tricarbonyl chloride in a water immiscible solution thereof.

Abstract: A process is disclosed for producing a composite reverse osmosis membrane. The process involves forming a porous polysulfone membrane from a solution of polysulfone followed by quenching the polysulfone membrane in an aqueous solution of m-phenylenediamine followed by reacting the m-phenylenediamine on the polysulfone membrane with either trimesoyl chloride or cyclohexane-1,3,5-tricarbonyl chloride in a water immiscible solution thereof.

Abstract: Reverse osmosis membrane casting solution containing dimethyl formamide solvent and hydrated magnesium chloride salt.

Abstract: Disclosed herein are random graft copolymer compositions comprising base polymers that are amorphous to x-rays at a temperature of 130.degree. C or below, to which base polymer is randomly grafted, on the average, at least one sidechain of crystallizable homopolymers of .alpha.-substituted-.beta.-propiolactones and/or copolymers thereof; a process for making said random graft compositions; and use thereof, inter alia, as molded or extruded articles.