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ABSTRACT:Although the hydrophilicity of polypropylene (PP) fabric surface can be improved by plasma treatment, it would obviously decay with the storage time. In this study, the graft polymerization of acrylamide (AAm) onto the surface of PP fabric was carried out by plasma pre-treatment and subsequently induced by UV-induce surface graft polymerization to improve the long term water adsorption ratio of the substrate. During the process, peroxides formed by the plasma treatment are the major factor responsible for initiating the graft polymerization. The amount of peroxide can be determined with good accuracy by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. Results indicated that the amounts of peroxides obviously increased with the plasma treated time and treat power, and the maximum concentration of peroxide can reach about 6:0 Â 10 À7 mol/cm 2 . However, the degree of grafting was not monotonous with increasing plasma treated power. The optimum processing condition was to apply 30 W power with 10 min of treatment to achieve the maximum surface grafting efficiency. Although the surface of PP fabric can be changed from hydrophobic to hydrophilic after plasma treatment, it would obviously age after 4 d of storage. By contrast, the UV-induce surface graft polymerization of PP can keep their hydrophilic property during the storage time after 7 d, due to the covalently grafted with hydrophilic monomer. [doi:10.1295/polymj.PJ2005183] KEY WORDS Plasma Treatment / Graft Polymerization / Water Adsorption Ratio Improvement / Peroxide Determined / Polypropylene (PP) fabric was widely used due to its cheapness, low density, excellent mechanical properties, and high porosity. However, the inert surface and lack of chemical polar groups of hydrophobic polymers, restricts their applications in some fields such as sanitary products, dressing, and biomaterials.1-5 Thus, several methods have been developed to modify surfaces of these polymers to improve their water adsorption ratio. [6][7][8][9] In which, the use of inner gas plasma treatment has been extensively studied to modify surface properties of polymer substrates. Free radicals are formed on the surface of substrate after plasma treatment. Peroxides are also generated at the same time when the free radicals are exposed to air.10 Thus, the water adsorption ratio of the surface exhibits the obviously decay effect during the storage time due to the reorientation of the hydrophilic group toward the bulk of the polymer. 11To achieve a stable modification surface, subsequently graft polymerization utilizing free radicals or peroxides generated by the plasma treatment was extensively adopted by many studies. 12-14The plasma composed of inorganic gas argon leads to implantation of atoms, radical generation, and etching reaction. There have been published quite a large number of works on the polymer surface modification by graft copolymerization utilizing free radicals or peroxide generated by the plasma treatment. So far, very few works have been reported on the relationship...