Epoxy resin (EP) is widely used in high‑performance adhesives, electrical insulations, and functional coatings due to its superior mechanical properties and favorable processability. However, its intrinsic flammability and susceptibility to wear severely limit its applications in fire‑prone or harsh abrasive conditions. In a study published in ENG. Chem. Eng., researchers at Anhui University of Science and Technology report a rational design strategy that simultaneously enhances flame retardancy, mechanical strength, and wear resistance.
The team synthesized homogeneous hierarchical nickel phyllosilicate (NiPS) using a metal‑organic framework precursor, then decorated its surface with polyphosphazene (PZN) to form NiPS@PZN hybrids. DOPO, a phosphorus‑based flame retardant, was incorporated as a synergist. EP composites with varying formulations were prepared via solution mixing.
Among all formulations, the sample with 3 % NiPS@PZN and 3 % DOPO (E94NP3D3) exhibited the best overall performance. In UL‑94 vertical burning tests, E94NP3D3 achieved a V‑0 rating with a total combustion time of only 8 seconds, compared to over 168 seconds for neat EP which received no rating. The limited oxygen index increased from 23.8 % (neat EP) to 26.6 %. Cone calorimeter tests showed that peak heat release rate decreased from 1086.7 to 981.8 kW·m⁻², total heat release from 77.34 to 69.33 MJ·m⁻², total smoke production from 95.1 to 73.0 m², and total CO₂ production from 47.7 to 34.9 g – reductions of 10.4 %, 23.2 %, and 26.8 %, respectively.
Mechanistic analysis revealed a dual‑phase flame‑retardant action. In the condensed phase, NiPS@PZN and DOPO promote the formation of a dense, graphitized char layer reinforced by NiO and silica. Raman analysis showed a decrease in the A_D/A_G ratio from 0.99 (neat EP) to 0.64 (E94NP3D3), confirming higher graphitization. XRD and XPS confirmed the presence of NiO, silica, and phosphorus‑containing compounds in the char. In the gas phase, phosphorus‑containing volatiles release P·O· radicals that scavenge reactive H· and OH· radicals, while non‑combustible gases dilute oxygen concentration.
The composite also demonstrated excellent mechanical and tribological properties. Tensile strength increased from 81.5 MPa (neat EP) to 103.5 MPa for E95NP3D2 (3 % NiPS@PZN + 2 % DOPO), attributed to well‑dispersed fillers acting as energy dissipation nodes that deflect crack propagation. The wear rate decreased by approximately 75 %, reaching a minimum of 1.78 × 10⁻⁵ mm³·N⁻¹·m⁻¹ for E95NP3D2, due to the formation of a stable transfer film on the worn surface. Notably, the co‑incorporation of DOPO restored the elastic modulus to values comparable to neat EP (1.38–1.42 GPa).
This work provides a viable pathway for designing high‑performance, flame‑retardant, and wear‑resistant polymer composites for demanding applications requiring both fire safety and service durability.
DOI
10.1007/s11705-026-2662-6