Synthesis and characterisation of the halogen-free flame retardant and mechanical performance of the retardant epoxies resin

Purpose - The purpose of this paper is to prepare a novel halogen-free intumescent flame retardant (IFR) BHPPODC (benzene hydroquinone phosphorous oxy dichloride cyanuric chloride) for application to epoxy resin (EP) and study their mechanical and flame-retardant performance. Design/methodology/approach - The IFR was synthesised by phenylphosphonic dichloride, hydroquinone and cyanuric chloride via solvent reaction, and the structure was fully characterised by proton nuclear magnetic resonance (H-1-NMR), mass spectrometry (MS) and Fourier transform infrared (FT-IR) spectroscopy. The thermal stability, mechanical and flame properties and morphology of the char layer of the flame-retardant EP was investigated by using thermogravimetric analysis (TGA), tensile and Charpy impact tests, limiting oxygen index (LOI) and vertical burning test (UL-94) and scanning electron microscopy (SEM). Findings - Results of the LOI indicated that the halogen-free flame retardant as an additive exhibits very good flame-retardant effects. The results showed that the addition of IFR improved the flame resistance properties of epoxies resin composites, and the residual char ratio at 800 degrees C significantly increased. Research limitations/implications - The IFR can be prepared successfully and can improve the flame-retardant performance. Practical implications - This contribution can provide a high flame retardant performance and has minimal impact on the mechanical performance of the BHPPODC/EP composition. Originality/value - This study showed that flame-retardant BHPPODC has an effective flame effect under optimal conditions. When the 12 Wt.% IFR was added to the EP, the LOI was 29.1 and the UL-94 rank can reach V-0 rank, the tensile strength was 83.86 MPa and the impact strength was 8.82 kJ/m(2).