A study on the flame retardant modification of bisphenol A benzoxazine

Abstract In this article, a P‐N synergistic flame retardant AG601‐DOPO (abbreviated as A‐D) was prepared by the reaction of tetrafunctional glycidyl amine epoxy resin (AG601) with 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO). The chemical structure of the product was confirmed by Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry (MS). Then, A‐D and bisphenol A benzoxazine (BA‐a) were mixed in different proportions to form a binary mixed system BA‐a‐A‐D (abbreviated as BAD) to improve the flame retardant properties of BA‐a. The results showed that the addition of A‐D can greatly improve the flame retardancy of BA‐a. When the content of A‐D was greater than or equal to 10%, the UL‐94 of BAD cured resin can reach the V‐0 rating. With the increasing of A‐D content, the LOI of BAD cured resin was increased from 23.8% to 37.1%. The results of cone calorimetry (CONE) test indicated that the total heat release (THR) was decreased from 120.7 to 78.2 MJ/m 2 , and the decrease was 35.2%. In addition, the effect of the introduction of A‐D on the thermal stability and heat resistance of BA‐a resin was analyzed. It was found that the temperature of the BAD‐cured resin at 5% thermal weight loss ( T d5% ) was above 300°C and the glass transition temperature ( T g ) was above 186°C, still maintaining good thermal properties. Finally, the mechanical properties of BAD cured resin decreased slightly without affecting the use of materials.