Studies of cross-linking reaction on chitosan fiber with glyoxal

Taking glyoxal as a reagent for cross-linking to chitosan fiber to improve latterʹs mechanical properties, this paper studied the effects from the preparation of glyoxal solution, e.g. the concentration and pH, and the reaction condition, e.g. time and temperature. Results showed that the glyoxal solution prepared with a concentration of about 4% with pH at 4 to be better, while the reaction condition to be better at about 40 °C and 60–70 min. Based on comparison of IR spectra for chitosan fiber before and after cross-linking, the enhancement of the mechanical property for chitosan fiber has been found due mainly to the occurrence of acetalization and Schiff base reaction among the glyoxal and the hydroxyls and amino groups of chitosan. Of them, the Schiff base reaction seems to be of a dominator comparing to the former with respect to their IR behaviors observed.