Enhanced flame retardancy of epoxy composites containing melamine polyphosphate‐modified boron nitride

Abstract

AbstractSurface chemical modification of boron nitride could enhance the compatibility with polymers and improve flame retardancy performances. In this work, the double‐bond active sites were constructed on the surface of boron nitride modified by the γ‐methacryloyloxypropyl trimethoxysilane (KH570). Glycidyl methacrylate (GMA) was further grafted onto the surface of boron nitride via free radical polymerization. Finally, the flame retardancy melamine polyphosphate (MPP) was bonded to the surface of boron nitride by the ring opening reaction. This modification process was proved to be achieved by infrared spectroscopy and thermogravimetric test. The boron nitride modified by flame retardant were added into the epoxy matrix and cured to prepare flame retardant and thermal conductive composites. The flame retardant of the composites was studied by cone calorimetry, UL94 vertical combustion test and limiting oxygen index. The thermal conductivity of the composites was characterized by laser thermal conductivity instrument. The results showed that when the addition amount of flame retardancy MPP modified boron nitride in the composites was 20 wt%, the flame retardant rating of UL94 reached to V1; the limiting oxygen index was increased from 25.1 vol% of pure epoxy resin to 30.3 vol%; the PHRR of pure epoxy resin was reduced from 800 to 510 kW/m2 of composites; the thermal conductivity of the composites was enhanced from 0.21 W/m•K−1 of the pure epoxy resin to 0.82 W/m•K−1of the composites.