Carboxymethyl cellulose (CMC) is one of the most useful cellulose derivatives．However

it is difficult to obtain CMC with higher degree of substitution (DS)

and CMC with lower DS often exhibits a poor solubility in water．In order to improve the degree of substitution of earboxymethyl cellulose

acrylic amide (AAm) was grafted onto cellulose

and the sodium carboxymethyl cellulose with AAm groups (AAm-CMC-Na) was synthesized．In the present work

a novel modified CMC hydrogel based on AAm-CMC-Na aqueous solution was obtained by using gamma irradiation under appropriate conditions．The swelling behavior

crosslinking kinetics of AAm-CMC-Na hydrogels and the effects of temperature

pH value and inorganic salt concentration on the swelling ratio of hydrogel were studied in detail．Experimental results showed that

when the concentration of AAm-CMC-Na aqueous solutions is above 12.5％

hydrogels could be prepared by gamma irradiation．However

comparing with radiation prepared CMC-Na hydrogels

the novel AAm-CMC-Na hydrogel could be produced at lower dose and lower concentration．Degradation is the predominant reaction in gamma irradiation for these two hydrogels．The swelling ratio of AAm-CMC-Na hydrogel in water was improved with the increase of temperature and had a maximum value in the range of pH=6～8

moreover

the swelling ratio decreased with the increasing of inorganic salt concentration and absorbed dose. The effect of CaCl2 solution on swelling behavior of AAm-CMC-Na hydrogel was more remarkable than that of NaCl solution．The irradiation prepared AAm-CMC-Na hydrogels showed good sensibility to temperature and pH value

which implied this novel hydrogel is expected to be a water absorption material and water preserver．