Calcium alginate fibers nonwoven fabrics which could absorb plenty of water and then transformed into gels were prepared by using two-step chemical modification methods. Calcium alginate fibers nonwoven fabrics were dipped into hydrochloric acid aqueous solution and sodium hydroxide solution using ethanol as the solvent. The comprehensive properties of gels derived from calcium alginate fibers nonwoven fabrics were the best

when concentration of hydrochloric acid solution was 0.05%-0.1%(mass) and concentration of sodium hydroxide solution was 0.008%-0.016%(mass). Under this condition

absorbing water capacity of calcium alginate nonwoven fabrics increased by 1.45 times after being modified chemically

and the ratio of preserving water capacity to absorbing water capacity of calcium alginate nonwoven fabrics increased by 10.67 times after modification. Thickness

mass of per unit area

air permeability and breaking strength of modified calcium alginate nonwoven fabrics changed a little before absorbing water

but the size of modified calcium alginate nonwoven fabrics after absorbing water adequately improved about 3 times. It indicated that the reason for formation of gel was related to structure and properties of calcium alginate fibers but not to fabric texture. At the stage of treatment with hydrochloric acid solution

the formed “egg-box” structure in calcium alginate fibers

and the crystal structure of these fibers were damaged partially and the degree of crystallinity and Ca2+ content of these fibers were decreased

but ester bond formed in these fibers. At the stage of treatment with sodium hydroxide solution

the formed ester groups changed into carboxyl groups and hydroxyl groups and intermolecular forces of fibers weakened for this change. Crosslinking degree and intermolecular forces of modified calcium alginate fibers were adjusted to appropriate states

so plenty of water molecules were absorbed by modified calcium alginate fibers and the absorbed water molecules could interact with fibers molecules in the form of hydrogen bond. For these reasons

modified calcium alginate fibers nonwoven fabrics changed into gels as soon as they were put in water.