Superabsorbent polymeric materials X: Effect of degree of neutralization on swelling behavior of crosslinked poly(sodium acrylate) in aqueous salt solutions

A series of xerogels based on different degrees of neutralizations (DN) of acrylic acid (AA) and N,N-methylene-bis-acrylamide (NMBA) were prepared by in verse suspension polymerization. The influence of the DN values of AA on water absorbency and swelling behavior for these highly absorbent polymers in deionized water and various saline solutions were investigated. Results indicate that the equilibrium-water absorbency (Q(eq)) increases with an i ncrease in the DN of AA until the DN value reaches 95% and then decreases a t 100% of the DN value. However, the initial absorption rate for these gels decreases with an increase in the DN value of AA in both deionized water a nd 0.9 wt% NaCl solution. The adsorption of copper ions by these gels was a lso investigated.