he Binding of Orange II to Nylon 66 Fibers Graft-Copolymerized with Methacrylic Monomers

Abstract

Methacrylic acid (MAA), methyl methacrylate (MMA) and 2-(dimethylamino)ethyl methacrylate (DMA) were graft-copolymerized onto Nylon 66 fibers which were prepared by the interfacial polymerizaion. Physicochemical properties of the surfaces of the modified Nylon fibers were investigated from the standpoint of a binding process of Orange II. The isoelectric points of the grafted Nylon fibers were considerably and slightly lower for the MAAand MMA-grafted fibers, respectively, but much higher for the DMA-grafted fiber than that of the original fiber. In addition, the graft-copolymerization of the monomers onto the Nylon fibers brought about a remarkable increase in the specific surface area of the grafted fibers (Table 1). The amounts of Orange II bound to the Nylon fibers were in the order DMA->(original) MMA->MAA-grafted fibers and the binding process showed typical Langmuir adsorption isotherms (Figs.1-3). The standard free energies (ΔF°) and equilibrium binding amounts (n) obtained from Klotz plots varied with graft yield and adsorption temperature (Figs.4-9). These results are discussed on the basis of the changes in the isoelectric points and specific surface areas of the grafted fibers. The values -ΔF° and n of some DMA- and MAA- grafted fibers had the maximum points at about 50°C (Figs.5, 6, 8 and 9). From the thermodynamic parameters for the binding of Orange II to DMA- and MAA-grafted fibers (Table 2), the adsorption mechanism of Orange II on the grafted fibers is concluded to depend on the temperature and to be ascribed to hydrophobic interaction between the dye and the fibers.