INFRARED-SPECTROSCOPY STUDIES OF THE CYCLIC ANHYDRIDE AS THE INTERMEDIATE FOR THE ESTER CROSS-LINKING OF COTTON CELLULOSE BY POLYCARBOXYLIC ACIDS .1. IDENTIFICATION OF THE CYCLIC ANHYDRIDE INTERMEDIATE

The mechanism of esterification of cotton cellulose by a polycarboxylic acid was investigated using Fourier transform infrared spectroscopy (FT-IR). The infrared spectroscopic data indicate that a polycarboxylic acid esterifies with cotton cellulose through the formation of an acid anhydride intermediate. A five-member cyclic anhydride intermediate was identified in the cotton fabric treated with poly(maleic acid). The five-member cyclic anhydride is a reactive intermediate and readily esterifies when reaction sites are available. We also found that those polycarboxylic acids, which form five-member cyclic anhydride intermediates, crosslink cotton cellulose more effectively than those polyearboxylic acids which from six-member cyclic anhydride intermediates.