Preparation Of Microencapsulated Hexaphenoxy-Cyclotriphosphazene And Its Flame Retarding BMI Resins

High performance thermosetting resin is one of indispensable and fundamental materials in many cutting-edge industries, and high performance flame retarding thermosetting resins become a key and hotspot of researches. Bismaleimides(BMI) is a representative of the heat-resistant thermosetting resins with a wide application, so the study on flame retarding BMI resin has a great prospect.A novel high performance green flame retardant, microencapsulated hexaphenoxycyclotriphosphazene(MH) was designed and prepared to obtain excellent flame retardancy, good water resistance and dielectric properties simultaneously. Our work mainly includes following two aspects.First, polyamide(PA) microencapsulated hexaphenoxycyclotriphosphazene(HPCTP) was prepared via interfacial polymerization. We explored the parameters in preparation process, and systematically studied the influences of the amount of amino groups in amine monomer, surfactant concentration and stirring rate on the morphology, particle size and thermal stability of MH; moreover, the structures and properties of MH were also fully characterized.Second, a series of MH/BD and HPCTP/BD resins were prepared, and their structures and properties were studied systematically and comparatively. Results show that MH has a better dispersion in BD resin than HPCTP. It’s worth noting that with a lower content of phosphorus element, the MH/BD resins show higher limited oxygen index(OI), decreased peak heat release rate(PHRR), total heat release(THR), and mass loss rate(MLR) than HPCTP/BD resins, indicating that MH is a green and excellent flame retardant. MH could facilitate the formation of denser and more stable char residue on the surface of the resin during combustion, and thus producing a thermal insulation effect to decrease the temperature of the inside of char, leading to the protection of the internal resin. On theIII other hand, MH/BD resins exhibit improved dielectric properties; namely, the dielectric constant and loss of MH/BD resins between 10-105 Hz are lower than those of HPCTP/BD resins with the same load of flame retardants; and MH/BD performs a better water resistance compared with HPCTP/BD resins. All results described above demonstrate that MH is a versatile flame retardant.