The flame retardancy and smoke suppression effect of a hybrid containing dihydrogen phosphate anion modified reduced graphene oxide/layered double hydroxide on epoxy resin

A hybrid with MgAl-layered double hydroxide loaded graphene (RGO-LDH) was synthesized by a coprecipitation method, and then dihydrogen phosphate anion (H2PO4-) modified RGO-LDH hybrid (RGO-LDH/P) was prepared through an ion exchange method. X-ray diffraction, Fourier transform infrared spectra, and transmission electron microscope-energy-dispersive X-ray spectroscopy results showed that RGO-LDH/P was synthesized successfully. RGO-LDH/P was added into epoxy resin (EP) to investigate the effect on flame retardancy and smoke suppression. Results showed that the limit oxygen index and char yield of EP with RGO-LDH/P increased, reaching 24.8% and 19.7%, respectively, compared with EP. Meanwhile, peak heat release rate, total heat release, smoke production rate and total smoke production of the EP composite decreased by 37.9%, 30.6%, 27.5%, and 38.4%, respectively. Improved flame retardancy and smoke suppression were attributed to the physical barrier of graphene and LDH, and the catalytic carbonization effect of LDH. In addition, H2PO4- had a role in promoting carbonization and further improving flame retardancy and smoke suppression.