In this study, the dual modified organoclay (DMC), was successfully prepared by the successive cationic exchange reactions of the sodium montomorillonite clay (MMT) with two intercalating reagents, hexadecyltriphenyl-phosphonium bromide and 2-methacryloxy-ethyl-hexadecyl-dimethyl-ammonium bromide. A series of the PMMA/DMC nanocomposite membranes (PDCM) were then prepared with the PMMA matrix and various amounts of DMC via the solution cast method. The results of XRD, TEM, SEM, and UV-VIS measurements of the PDCMs prepared showed that the DMC particles were well dispersed in the PMMA matrix with a highly exfoliated structure. The TGA thermograms indicated that the thermal stabilities of the PDCM membranes are higher than that of the PMMA. Furthermore, the tensile mechanical property and glass transition temperature of the nanocomposites were dramatically increased with increasing the DMC content. The limiting oxygen index of PDCM membranes also indicated that the flame retardancy was significantly enhanced due to the presence of DMC. Moreover, more than 90% of the PMMA's transparency was remained in the nanocomposites.

SYNOPSIST o improve the hydrophilicity and enhance the transport flux of nylon 4 membrane for dialysis, this study attempts to utilize blending nylon 4 with poly (vinyl alcohol) (PVA) .The instability of PVA in water can be significantly improved by esterification of PVA with formic acid when it is used as casting solvent of PVAInylon 4 blend membrane. By this method, the stability of PVA in water can be obtained more easily than by other methods, such as chemical, y-ray irradiated crosslinking, or high-temperature treatment used by previous researchers. The effects of maturation time of the casting solution, nylon 4/PVA ratios, and casting solvent compositions on esterification of PVA, salt permeability, water content, partition coefficient, diffusivity, and mechanical strength of membranes are studied. The membrane, prepared by casting solution of nylon 4/PVA 9 / 1 wt % formic acid with 24-h maturation time, possesses permeabilities of NaCl and urea, 33.14 and 19.67 x cm2/min, respectively.

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