Electrostatic self-assembly of red phosphorus@MgAl-layered double hydroxide for improved flame retardancy in epoxy resin

The creation of high-performance flame retardants using a simple method is essential to align with the increasing demand for sustainable and non-toxic flame retardants. Red phosphorus (RP) was encapsulated with magnesium-aluminum-layered double hydroxides (LDHs) through electrostatic assembly to form RP@LDH composites. These composites were incorporated into epoxy resin (EP) at varying concentrations to evaluate their thermal and flammability performance. The EP composite with 7 wt% RP@LDH achieved a limiting oxygen index (LOI) of 37.5 % and a UL-94 V-0 rating. Compared to pure EP, this composite demonstrated a 16.3 % increase in carbon residue and reductions of 41.1 %, 37.9 %, and 40.8 % in peak heat release rate, total heat release, and carbon monoxide emissions, respectively. The enhancements are attributed to a protective barrier formed by LDH and RP decomposition products during combustion, which also suppress flammable by-product formation. Simultaneously enhanced the mechanical properties of EP composite materials effectively. This synergistic interaction provides valuable insights into developing advanced flame-retardant systems for polymer applications.