Radiation grafting of acrylic and methacrylic acid to cellulose fibers to impart high water sorbency

Acrylic and methacrylic acids have been directly grafted to rayon and cotton using the preirradiation technique with 60 Co γ rays. The rate of grafting increased with increasing temperature and monomer concentration, as did the final degree of grafting. The amount and rate of grafting also increased with the total irradiation dose but tended to level off at higher doses, in agreement with the leveling off of the radical content reported previously. Methacrylic acid grafted more and faster than acrylic acid to both rayon and cotton. Methacrylic acid grafted more with rayon than cotton, but acrylic acid gave somewhat similar yields with both fibers. The water absorbency of the grafted fibers depended strongly on their posttreatment. Decrystallizing with 70% zinc chloride or with hot sodium hydroxide developed supersorbency. The two treatments in succession, respectively, gave the highest values. Methacrylic acid brought about less sorbency than the corresponding acrylic acid grafts. Useful levels of grafting and supersorbency could be readily and practically achieved by the methods described.