Study On Combustion Behaviors And Potential Fire Hazards Assessment Of Flame Retardant Epoxy Resins

As one of the important components of wall panels and luggage rack structural materials for large transportation vehicles such as high-speed trains and aircrafts,epoxy resin(EP)is one of the most widely used thermosetting polymer materials in the field of engineering materials.However,like most polymer materials,EP is flammable,and its combustion produces a large amount of smoke and toxic gases.Therefore,it is signifigant to explore the pyrolytic characteristics and combustion behaviors of epoxy resins with different flame retardant characteristics under various conditions to maintain public safety.Based on this,seven kinds of typical flame retardants,9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO),DOPO derivatives DOPO-HQ and DOPO-THPO,dimethyl methylphosphonate(DMMP),bisphenol A bis(diphenyl)phosphate(BDP),black phosphorus(BP)and aluminum hydroxide(Al(OH)3),were used as additives to prepare flame-retarded epoxy resins.Under the assistant of the Limited Oxygen Index and Vertical Burning tests,the amounts of flame retardants were determined.The pyrolysis properties of EP and its flame-retarded composites were investigated by thermogravimetric(TGA)technique.Compared with the pure sample,the thermal decomposition time of the flame retardant samples advanced,and the decrease rates were directly related to the thermal stability of the flame retardants themselves.In addition,the amounts of residue of flame retardant samples depended on their flame retardant mechanisms.The activation energy of these materials were calculated by methods of Kissinger,FWO and KAS.The pyrolysis gaseous products of EP and its flame retardant composites were analyzed by TG-IR.It was found that the main gaseous products of these samples were almost the same in type,but their occurrence time and the relative strength of absorption peaks were changed.Then,the cone calorimeter experiments with different thermal radiation intensities(25,35,50 and 65 kW/m2)were carried out to analyze the variation of combustion characteristic parameters with thermal radiation intensities.With the increase of thermal radiation intensity,the ignition time(TTI)of materials were reduced,while peak mass loss rate(PMLR)and peak heat release rate(PHRR)increased with advanced occurrence time.In addition,total heat release(THR),effective heat of combustion(EHC),fire growth index(FGI),CO2 formation rate and yield increased,the fire performance index(FPI),CO generation rate and carbon residue amounts decreased.Compared with the pure sample,the characteristic parameters of the flame retardant samples were not completely consistent.The critical thermal radiation flux(CHF)of all flame retardant samples increased,while PMLR,PHRR,THR and EHC decreased.As the TTI and thermal response parameters(TRP)of EP/50%AH increased,the total smoke(TSP),CO generation rate and yield,CO2 generation rate and yield decreased.The TTI,TRP and CO2 production rate and yield of phosphorus samples decreased,while their TSP and CO production rate and yield increased.Finally,based on the analytic hierarchy process method,a fire assessment model containing ignition risk indictor,thermal hazards indicator and non-thermal hazards indicator was built to quantitatively compare the fire hazards of materials.