A series of acrylic-based superabsorbent resins were synthesized by inverse suspension polymerization

using potassium persulfate as the initiator

N

N-methylene bisacrylamide (BIS) and divinylbenzene (DVB) as the multiple crosslinking agents. The morphology of the resulting superabsorbent resins revealed by SEM demonstrated that a hard shell layer was indeed formed due to surface crosslinking. The swelling and deswelling properties

and the mechanical strength of superabsorbents were investigated. The results indicated that the adding time of DVB and the amount of DVB participated in the crosslinking show a significant influence on the properties of superabsorbents. When DVB was added in polymerization later

the amount of DVB participated in reaction decreases and the surface crosslinked shell becomes thinner. It is suitable for DVB to be introduced in the later stage of the polymerization process

because the absorption rate of resin is efficiently improved in conjunction with higher water absorption. Furthermore

it was found that the mechanical strength of swollen superabsorbent with surface crosslinking was indeed enhanced in comparison with that of the conventional one.