IR Spectroscopy Study of Cyclic Anhydride as Intermediate for Ester Crosslinking of Cotton Cellulose by Polycarboxylic Acids. V. Comparison of 1,2,4-Butanetricarboxylic Acid and 1,2,3-Propanetricarboxylic Acid

摘要

In recent years extensive efforts have been made to use multifunctional carboxylic acids as formaldehyde-free crosslinking agents for cotton to replace the traditional formaldehyde-based N-methylol reagents. In our previous research we found that a polycarboxylic acid esterifies cellulose through the forination of a five- membered cyclic anhydride intermediate by dehydration of two adjacent carbOxyl groups. In this research we used Fourier transformIR (FTIR) spectroscopy to study the formation of cyclic anhydride intermediates and crosslinking of cotton by 1,2,4-butan- etricarboxylic acid (ETA) and 1,2,3-propanetricarboxylic acid (PCA). ETA and PCA form five-membered cyclic anhydrides in the same temperature range. Eothacids form the anhydrides at lower temperatures when a catalyst is present. When an acid molecule is bonded to cotton through an ester linkage, only PCA is able to form a second anhydride intermediate. We found that PCA is a more effective crosslinking agent, and it imparts higher levels of wrinkle resistance to the cotton fabric than ETA. Therefore, the formation of a five-membered cyclic anhydride by a polycarboxylic acid accelerates the esterification of cotton by the acid.