Acrylic fibers were graft copolymerized with methacrylamide in aqueous media, using benzoyl peroxide as a free-radical initiator. The grafting reactions were carried out within the 75-95degreesC temperature range, and the effect of initiator, monomer concentrations, and the amount of fiber on the graft yield were also investigated. The maximum graft yield was reached at the benzoyl peroxide concentration of 3.0 x 10(-3) mol/L and the optimum temperature of 85degreesC. The activation energy of the reaction was found to be 33.8 kcal/mol at the temperature interval of 80-95degreesC. The grafted fibers were characterized with infrared spectroscopy, scanning electron microscopy, and thermogravimetry. The thermogravimetric analysis results revealed that the degradation temperature of the acrylic fibers increased with grafting. The scanning electron photographs showed that the homogeneous appearance of the fiber surface changed and a shell-like heterogeneous structure occurred at the surface with an increasing degree of grafting. The moisture content and water absorption of grafted acrylic fibers was highly enhanced by grafting. (C) 2004 Wiley Periodicals, Inc.