Preparation of biobased guar gum polyelectrolyte complex coatings by sol‐gel method for improving the flame retardancy of ramie fabrics

Abstract In this study, to improve the flame‐retardant properties of ramie fabrics (RFs), a polyelectrolyte complex (PEC) was prepared in a one‐step process using biobased guar gum (GG), polyethyleneimine (PEI), and ammonium polyphosphate (APP) and deposited on the surface of the RF to construct an intumescent flame‐retardant coating. Fabrics treated with PEC coatings exhibited excellent flame‐retardant properties. Specifically, the cone calorimeter test results revealed that an increase in sample weight of only 13.23 wt% resulted in significant reductions in the peak heat release rate (pHRR), total heat release (THR), and fire growth rate (FGR) of 91.37%, 65.12%, and 95.28%, respectively. Additionally, the limiting oxygen index (LOI) increased from 19.4% to 33.5%, and the fabrics self‐extinguished immediately after the ignition source was removed during the UL‐94 test. Scanning electron microscopy (SEM) of the char residue revealed expansion bubbles on the surface, suggesting that the PEC coating provides flame retardancy through a synergistic effect involving both the gas phase and the condensed phase. This study provides a simple and convenient solution for realizing green and efficient flame‐retardant coatings on RF.