Constructing a novel synergistic flame retardant by hybridization of zeolitic imidazolate framework‐67 and graphene oxide for thermoplastic polyurethane

Abstract To enhance the flame retardancy and smoke suppression of thermoplastic polyurethane (TPU), a novel flame retardant ZIF‐67@GO was fabricated by hybridization of zeolitic imidazolate framework‐67 (ZIF‐67) and graphene oxide (GO). The flame retardancy of TPU sample was significantly enhanced by the presence of 6.5 wt% ammonium polyphosphate (APP) and 0.5 wt% ZIF‐67@GO: the limit oxygen index (LOI) reached 27.4% and UL‐94 grade passed V‐0, the peak heat release rate (pHRR) and peak smoke production rate (pSPR) values was dropped by 81.2% and 48.7%, respectively, comparing with that of the control sample. The burning time of the flame‐retardant TPU sample was prolonged to more than 600 s from 200 s of the control TPU sample during the cone test. Additionally, the tensile strength and elongation ratio of the flame‐retardant TPU reached 18.3 MPa and 1026.3%, respectively, which meet the requirement in most industrial applications. This work provides useful information to produce flame retardant synergists for polymeric composites.