Flame retardancy and durability of cotton fabric modified with high-efficiency diboraspiro rings groups flame retardant.

The synthesis of highly efficient and environmentally friendly flame retardants through the synergistic interaction of boron, phosphorus and nitrogen is becoming a new research direction. In this study, N-DBSPA, a flame retardant with high flame retardancy, high thermal stability and high efficiency, was prepared by the reaction between pentaerythritol borate and amino trimethylene phosphate, and the limiting oxygen index (LOI) of the modified cotton fabric increased from 18 % to 44.7 % at a weight gain (WG) of 20.4 %. After 50 wash cycles (LCs), it still reached 34.2 % and passed the Vertical Flame Test (VFT), indicating good flame retardancy and wash resistance. Cone Calorimetry Test (CCT) showed a 90.2 % reduction in Peak Heat Release Rate (PHRR) and a 32.9 % reduction in Total Heat Release (THR). The thermogravimetric test (TG) showed an increase in the charring residue of cotton fabrics from 10.9 % to 36.2 % at 750 °C in a nitrogen atmosphere. Finally, the flame retardant mechanism of the modified cotton fibers was speculated from the condensed phase and gas phase, respectively.