From laboratory to industrialization: Eco-friendly flame retardant endowing epoxy resin with excellent flame retardancy, transparency, and mechanical properties

To eliminate the fire safety hazards (flammability and smoke toxicity) of epoxy resins (EP), while reaching industrial production of flame retardants, we proposed a facile strategy to successfully synthesize an industrially scalable phosphorus-nitrogen flame retardant (named FNU) by the substitution reaction of 2-(2-aminoethylamino) ethanol and 9,10-dihydro-9-oxo-10-phosphofi-10-oxide. FNU was synthesized in a simple and heat-free step with room temperature stirring, and such process optimizations facilitate industrially scalable. As expected, FNU endowed EP with excellent flame retardancy and smoke suppression properties. EP mixing with 10 phr of FNU reached the highest limiting oxygen index value of 44.5%, UL-94 reached V-0 level, total smoke production and total heat release were reduced by 15.5% and 19.8% compared with pure EP. Residual carbon analysis showed that the presence of FNU could promote to form dense and continuous carbon layer. Thermogravimetric analysis-infrared spectrometry results demonstrated a significant reduction in the pyrolysis products, especially in the yield of CO. Moreover, the structure of FNU contained aromatic rigid and reactive amine groups that significantly improved the mechanical properties of EP without affecting its transparency, retaining its value for applications in optical materials.

Automated summary

Researchers have proposed a facile strategy to synthesize an industrially scalable phosphorus-nitrogen flame retardant named FNU. FNU endows epoxy resins (EP) with excellent flame retardancy and smoke suppression properties, while also improving mechanical properties and transparency.