Synergistic Flame-Retardant Finishing of Cotton Using Dichlorotriazinyl Phosphonate and Triethanolamine

Dichlorotriazinyl phosphonate (DCTP), a formaldehyde-free flame retardant (FR), was steam-cured with triethanol amine (TEA) to impart synergistic flame-retardancy to cotton fabrics. While the DCTP treatment alone showed very limited resistance less than five laundering cycles (LC), TEA addition increased the laundering durability of the FR cotton up to ten LC. More enhanced washing performance up to fifteen LC was observed with epichlorohydrin (ECH) after-treatment. The TEA and ECH extended the washing resistance via nucleophilic substitution and addition reactions of DCTP and cotton respectively producing the densely crosslinked networks of DCTP and cellulose. With increasing molar ratio of TEA to the DCTP up to 0.5, the flame retarding effectivity and the synergistic effectiveness improved up to 3.8 and 2.2 respectively. The pyrolysis and combustion behaviors of the FR-cotton were verified with TGA and micro combustion calorimetry. The FR cotton decomposed at lower maximum pyrolysis and combustion temperatures with decreased peak pyrolysis and heat release rate, yielding higher char contents. The synergistic DCTP and TEA formulation coupled with ECH post-treatment seemed to follow a solid-phase flame-retarding mechanism.