Engineering Bio-chain Extender and DOPO-based Flame Retardant toward Intrinsically Flame Retardant and Mechanically Robust Polyurea

Polyurea materials are widely used in building waterproofing, heat preservation, sealing and coating due to their good mechanical properties, excellent weather resistance and strong adhesion; however, their widespread use also presents significant fire hazard risks. This study emphasizes the potential to optimize flame retardancy while preserving mechanical properties. A polyurea with a mechanical strength of 26.25 MPa and a limiting oxygen index (LOI) of 26% was developed by incorporating 20 wt% bio-chain extender and 10 wt% DOPO-based flame retardant. The cone calorimeter test demonstrated that the inclusion of 10 wt% flame retardant reduced the peak heat release rate (pHRR), total heat release (THR), and total smoke release (TSR) by 48.29%, 73.02%, and 54.32%, respectively. This work provides an effective method for improving the flame retardancy of polyurea.