Novel kinetics model for the crosslinking reaction of 1,2,3,4-butanetetracarboxylic acid with cellulose within cotton fabrics

Abstract

1,2,3,4-butanetetracarboxylic acid (BTCA) has been explored as formaldehyde-free crosslinking agent for many years. In this study, a novel kinetic model for cellulose reacted by BTCA was proposed and the factors that influenced the model parameters were investigated in detail, which could help us understand crosslinking mechanism clearly. Kinetic model, which is a consecutive reaction model, consisting of grafting (esterifying) reaction rate constant and crosslinking reaction rate constant, was deduced. The rate of the whole reaction depends on the rate of grafting reaction, which is related to the diffusion of free BTCA in pores of cellulose. However, the rate of crosslinking reaction depends on thermal vibration of cellulose chain grafted by BTCA, which is more sensitive to the change of curing temperature, especially when the temperature is higher than 150 °C. The Arrhenius activation energies of grafting and crosslinking reactions are 86.3 kJ/mol and 102.8 kJ/mol, respectively, showing high temperature is more conducive to increase the rate of crosslinking reactions comparing with grafting reaction. Moreover, the whole reaction is also affected by catalyst of SHP, which could react with BTCA anhydride to form BTCA-SHP compounds. Due to lower electron cloud density of carbonyl groups, BTCA-SHP compounds have much higher reactivity compared with BTCA anhydrides, which are beneficial to be attacked by hydroxyl groups in cellulose to form ester bonds, imparting excellent wrinkle-resistance to cotton fabrics.