Radiation synthesis of reverse osmosis membranes were carried out by grafting of N-Isopropyl acrylamide (NIPAM) and ZnO nanoparticles incorporation onto polyamide thin film composite reverse osmosis membranes PA(TFC). The effect of monomer concentration, radiation time and concentration of ZnO nanoparticles on the grafting percent were investigated. The properties of the prepared grafted reverse osmosis membranes were characterized by using different analytical tools such as contact angles goniometer, Fourier transform IR (FTIR), X-ray diffraction (XRD), Field Emission-Scanning Electron Microscope (FESEM). The performance of the reverse osmosis process of the neat and the modified PA(TFC) membranes in terms of water flux and salt rejection (%) was investigated. The chlorine and biofouling resistance properties of the neat and the modified PA(TFC) membrane were evaluated. It is found that, the performance of the modified ZnO NPs/P(NIPAM)-g-PA(TFC) membrane is much better than the neat PA(TFC) membrane.

The radiation initiated grafting of N‐vinylpyrrolidone (NVP) acryl‐amide (AAm) and their mixtures onto polypropylene (PP) films using a direct radiation technique has been investigated. Different solvents were used for diluting the monomers and it was found that dioxane was suitable for this grafting system. The influence of other grafting parameters such as inhibitor, monomer concentration and dose rate on the rate of grafting and grafting yield was studied. The values of the coefficients relating the grafting rate to monomer concentration and dose rate were found to be 1·4 and 1·5 for (NVP), and 1·6 and 1·47 for (AAm), respectively. Also, the coefficients relating grafting rate to co‐monomer concentration for 20/80 and 50/50 AAm/NVP mixtures were found to be 1·6 and 1·7. Some physicochemical properties such as swelling, thermal behaviour, mechanical and electrical conductivity were also investigated, and the possibility of some practical uses, e.g. the removal of heavy metals from solution, for the grafted membranes is discussed. © 1998 SCI.

SynopsisCationic membranes were prepared by direct radiation grafting of methacrylic acid (MAA) onto poly(tetrafluoroethy1ene) (PTFE) f i l m s followed by alkaline treatment to confer ionic character in the graft copolymer. The complete inhibition of homopolymerization of MAA by using ammonium feqeous sulfate (Mohr's salt) failed. However, the addition of 0.5 w t ' % FeC1, to the monomer solution effectively inhibited the homopolymerization process and higher grafting yield was obtained. I t was found that the graft polymerization proceeded successfully in presence of methanol/water mixture (30/70 w t %), and much higher degrees of grafting were obtained as compared with those in the presence of other diluents used here. The influence of irradiation atmosphere (air, N, gas, and vacuum) on the grafting process was investigated. The dependence of the grafting rate on MAA concentration was found to be of orders 2.9 and 0.72 in the presence of 0.5 wt % Mohr's salt or 0.5 wt 5 % FeCl,, respectively. This grafting system proceeds by the front mechanism. Investigation of mechanical properties, electrical conductivity, and swelling behavior of the grafted films revealed that such a copolymer could be acceptable in practical use as a cation-exchange membrane.

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SynopsisHydrophilic membranes were prepared by direct radiation grafting of methacrylic acid (MAA) onto poly (tetrafluoroethylene-perfluorovinylether) copolymer ( PFA) and poly (tetrafluoroethylene-hexafluoropropylene) copolymer (FEP) films followed by alkaline treatment to confer ionic character in the graft copolymer. Addition of 0.5 wt % FeC1, to the monomer solution effectively inhibited the homopolymerization process and higher grafting yield was obtained. The graft copolymerization of MAA was carried out in presence of methanol/water mixture (30/70 wt % ) in nitrogen atmosphere irradiation. The dependence of the grafting rate on MAA concentration was found to be 0.63 and 0.94 order for PFA and FEP films, respectively. This grafting system proceeds by the front mechanism in which the monomer diffuses through the already grafted layer formed initially. Some selected properties of the graft copolymers were investigated. It was found that the grafted membranes possess good mechanical, electrical, and hydrophilic properties which may make them promising in some practical applications.