Swelling of carboxymethylated cellulose fibres

Swelling of cotton cellulose fibres having different proportions of carboxyl groups in the H-form was studied. The carboxyl groups were introduced by carboxymethylation under different reaction conditions. By studying the swelling of modified cellulose samples (water retention value of non-dried fibre) it was shown that the concentration of sodium hydroxide was the dominant factor among the investigated reaction parameters. The number of acidic groups was found to play a significant but not determinative role in the level of improvement in swelling caused by carboxymethylation. A linear correlation was observed between swelling and iodine sorption capacity. The degree of collapse of the highly accessible structure of cellulose during drying (hornification) was larger in the case of more accessible carboxymethylated fibres than for the alkali treated sample. The degree of hornification increased with growing swellability and with growing number of carboxyl groups in the investigated interval (40–120 mmol carboxyl/mol cellulose). This type of modified cellulosic fibre could be used for enhanced entrapping and release of chemicals. This revised version was published online in August 2006 with corrections to the Cover Date.