Epoxy resin/tin ethylenediamine tetra‐methylene phosphonate composites with simultaneous improvement of flame retardancy and smoke suppression

A nitrogen‐containing metal‐organic phosphonate, that is, tin ethylenediamine tetra‐methylene phosphonate (TETP) was synthesized, characterized, and then used as the flame‐retardant additive in epoxy resin (EP). The flame retardancy, smoke suppression, thermal stability, and mechanical performances of the EP/TETP composites were thoroughly evaluated. It is found that the EP composite with 7.0 wt% of TETP (EP/TETP‐7) can pass UL‐94 V‐0 rating with a high LOI value of 29.5%. Cone calorimeter results show that the peak heat release rate, total heat release, and total smoke release of EP/TETP‐7 are decreased by 45.7%, 27.3%, and 37.3%, respectively, compared with pure EP. Besides, the production rates of CO and CO2 of EP/TETP‐7 are reduced remarkably. Thermogravimetric analysis results indicate that the char residue of EP/TETP‐7 at 800°C is almost double than that of pure EP. Moreover, the incorporation of TETP has less influence on the mechanical performances and thermal resistance (ie, glass transition temperature) of EP/TETP composites.