Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE The incorporation of PTM markedly improved the flame retardancy and smoke suppression of epoxy resin (EP). With increasing PTM content, the LOI increased from 22.5% (neat EP) to 35.1% for PTM/EP5, achieving a UL-94 V-0 rating. Cone calorimetry further revealed substantial reductions in pHRR, THR, and TSP for PTM/EP5 by 84.33%, 62.04%, and 66.67%, respectively. These enhancements are attributed to the P–N synergistic effect of PTM: upon heating, PTM generates reactive PO·/PO2· species that scavenge flame-propagating radicals and releases nonflammable gases (CO2, H2O, and NH2) that dilute combustible volatiles. Meanwhile, PTM promotes the formation of a compact char barrier, inhibiting heat and mass transfer. As a result, PTM/EP exhibits efficient flame retardancy and smoke suppression via coupled gas-phase and condensed-phase mechanisms, delivering superior overall performance compared with reported systems at lower additive loadings.


ABSTRACT
Improving the flame retardancy of epoxy resin (EP) is an imperative yet challenging task for its applications in electronic packaging and aerospace. In this study, a novel bio-based phosphorus–nitrogen flame retardant (PTM) was successfully synthesized from phytic acid (PA), 1,3,5-tris(2-hydroxyethyl) cyanuric acid (THEIC), and melamine (MEL) and added to EP to further prepare PTM/EP composites. The chemical compositions and bonding states characterized by Fourier transform infrared (FTIR), liquid nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS), confirmed the flame-retardant constituents of PTM. Compared with pure EP, the PTM/EP5 composite demonstrated superior flame retardancy and smoke suppression, achieving a UL-94 V-0 rating and a high limiting oxygen index (LOI) of 34.0%. Additionally, the peak heat release rate (pHRR), total heat release (THR), and total smoke release (TSP) of the PTM/EP5 composite decreased by 84.33%, 62.04%, and 66.67%, respectively. The impressive flame retardancy and smoke suppression performance of PTM/EP were attributed to the phosphorus–nitrogen synergistic intumescent mechanism facilitated by PTM. This study provides an effective and sustainable flame-retardant strategy for EP composites, offering new insights into the green development of P–N flame-retardant systems.