Grafting on polyester fibers

Acrylic acid (AA) and acrylonitrile (AN) were used to carry out grafting on polyester (PE) fibers using the techniques of initiation by γ-radiation as well as benzoyl peroxide. Extent of grafting depended upon the time, concentration of the initiator, and the monomer as well as on the irradiation dose. AA grafted fibers were rendered more hydrophilic than AN grafted fibers for equivalent amount of grafts. Considerable improvement in dyeability of the PE fibers was possible through grafting. About 50 percent to 100 percent improvement with disperse dyes was observed in case of PE fibers containing 22.4 percent and 9.0 percent graft of AA and AN, respectively. Intense fast dyeing with direct and basic (cationic) dyes was also possible, and the dye content was proportional to the extent of graft introduced in the fiber. The CN groups were reduced to NH2 groups in the AN graft on the fiber. With the increased amount of AA graft, the maxima in the zeta potential curve shifted toward higher acidic pH as greater amounts of alkali were utilized by the --COOH groups in the graft. In this respect, CN groups were less sensitive due to their lesser polarity as compared to the carboxylic groups. Surface charge density (S.C.D.) studies showed that the effective surface area of the fiber decreased with the increase in the amount of graft. Surface conductivity (S.C.) studies revealed that with increase in the number of polar groups (--COOH) on the surface of the fiber, the S.C. increased with the increase in the amount of AA graft. In case of AN grafts, the reduction in effective surface area of the fiber played a more important role than the contribution by the CN groups to surface conductivity. (U.S.)