Graft copolymerization of acrylic acid on cellulose: Reaction kinetics of copolymerization

Abstract

Acrylic acid (AA) was grafted to cellulose by using ceric ammonium nitrate (CAN) initiator in aqueous nitric acid solution at 30, 50, 70, and 90 degrees C during reaction periods of 30 to 180 minutes. About 45% of the AA was polymerized at 90 degrees C after 180 minutes. The grafted polymer and homopolymer were isolated by acetone from the reaction mixture, dried, and subjected to Soxhlet extraction with dioxane to separate the homopolymer, poly(acrylic acid), from the graft copolymer. The water absorption capacities and grafting values of grafted cellulose were also determined. The maximum grafting yield was obtained at 30 degrees C. It was also observed that polyacrylic acid-grafted cellulose produced at 30 degrees C had the highest water retention capacity. The time dependence of AA conversion allowed calculation of first-order reaction rate constants. These rate constants were then used to determine apparent activation energies. (C) 1997 John Wiley & Sons, Inc.