Synthesis of efficient fire resistant additive and its effect on transparent and mechanical properties

Abstract

An effective nitrogen-phosphorus synergetic flame-retardant additive was designed with nitrogen-rich 3,5-Diamino-1,2,4-triazole and DOPO. With the help of CCl₄, CH₂Cl₂ and triethylamine, target product diamine-phosphaferrocene-oxide (DD) was successfully synthesized. Equipped with DD of 0.92 g, epoxy resin mould of 25 g succeeded in vertical combustion test with rating of UL-94 V-0. In respect of limiting oxygen index, the value of mould was improved to 32.5%. The introduction of DD also had a significant impact on other parameters during the combustion of EP. For instance, peak of heat release rate of EP/3.5%DD mould was 746 kW/m², which was 70.2% of EP mould without flame retardants. Total heat release of EP/3.5%DD mould was also dramatically decreased. All these details demonstrated that DD performed effectively in test of fire resistance. Besides, mechanical strength of EP mould was also improved by DD, of which izod iMPact strength of EP/3.5%DD was dramatically increased to 33 kJm^-2. Meanwhile, tensile strength and flexural strength of EP/3.5% DD was 99 MPa and 112 MPa, which was 119.2% and 128.7% of EP mould, respectively. In the end, SEM, IR, XPS and Raman was utilized to study the flame-retardant mode of DD.