In order to improve the flame retardant performance of epoxy resin(EP),the flame retardant pentaerythritol aryl phosphonate(PBPP)was successfully prepared by nucleophilic substitution reaction using the traditional char-forming agents pentaerythritol(PER)and phenylphosphonyl dichloride(PPDC)as raw materials.PBPP was introduced into the EP matrix to prepared flame retardant EP composites.The tests show that the EP/PBPP6 composites successfully obtain UL-94 V-0 rating with the limiting oxygen index(LOI)of 32.5％when the mass fraction of PBPP is 6％,and the melting droplets of EP/PBPP are significantly suppressed.Thermogravimetric analysis show that the addition of PBPP promotes the early degradation and charring of the EP matrix and results in the formation of a dense and hard char layer on the surface of EP/PBPP composites,which effectively acts as barrier in condensed phase.Thus,the PHRR and THR of EP/PBPP composites are reduced by 66.9％and 50.4％compared to pure EP.In addition,the phosphorus-containing radicals generated during the decomposition of PBPP effectively exert the inhibiting effect in gas phase,resulting in a significant reduction in the av-EHC of EP/PBPP composites and endowing the EP composites with excellent fire safety properties.
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