Effect of NiFe₂O₄@graphene in intumescent flame‐retarded poly(lactic acid) composites

NiFe₂O₄ nanoparticles loaded on graphene layers (NiFe₂O₄@GR) were prepared by the hydrothermal method, and they first combined with intumescent flame retardant (IFR) consisting of polyphosphate (APP) and pentaerythritol (PER) was used to prepare poly(lactic acid) (PLA) composites. Effect of NiFe₂O₄@GR and IFR on thermal stability and flame retardancy of PLA was investigated. Limit oxygen index (LOI) value of all the PLA composites increased, and the results of UL‐94 tests passed V0 ratings. With the presence of NiFe₂O₄@GR in intumescent flame‐retarded PLA composites, the initial degradation temperature had a big increase and char residue increased apparently. The ratio of graphite crystalline carbon was increased. The denser and more intumescent char layer was formed. In addition, NiFe₂O₄@GR had the reinforcing effect for PLA. Therefore, NiFe₂O₄@GR and IFR had a good synergistic effect in improving thermal stability and flame retardancy of PLA. POLYM. COMPOS., 40:652–656, 2019. © 2018 Society of Plastics Engineers