| Epoxy resins(EP)has been largely used as the matrix of various composite materials due to its high performance,including high insulation resistance,moisture resistance,chemical stability,corrosion resistance and excellent manufacture properties,and so on.However,it is hard to meet specific application in the field of fire retardant performance requirements,due to its poor fire resistance and large amount of smoke.Therefore,new type of halogen-free flame retardant epoxy resin becomes an important research direction in the field of the flame retardant polymer.In view of the above problem,this paper has carried out the following research work:Firstly,1,1?-diacetylferrocene(DAF)and 1,1?-ferrocene dicarboxylic acid(Fc(COOH)2)were synthesized using ferrocene,acetyl chloride and sodium hypochlorite,and the reaction conditions were detailedly explored and optimized.Their chemical structures were identified employing FTIR and 1H NMR.According to the method reported in literatures,2-methoxy-4,6-dichloro-triazine(MDCT)and2,4-diamino-6-methoxy-triazine(DAMT)were synthesized by cyanuric chloride,methanol and ammonia.Consequently,a novel polymeric flame retardant containing ferrocene and triazine ring(PFCTR)was successfully synthesized by solution polymerization from Fc(COOH)2and DAMT.Its structure was characterized by FTIR and 1H NMR,and the degree of polymerization was calculated to be 13.The thermal stability and thermal decomposition mechanism of PFCTR were comprehensively studied by Thermo-gravimetric analysis/Infrared spectrometry(TG-IR),Pyrolysis gas chromatography-mass spectrometry(Py-GC/MS)and Energy Dispersive X-Ray Spectroscopy(EDX).The results showed that the main breakdown products were CO2,CO,NH3,H2 O and iron oxides,etc.The residual yield is only 9.2 wt%at 700 ?.Secondly,a large amount of fire retardant EP resin formulations based on PFCTR,Ammonium polyphosphate(APP)and APP-PFCTRsystems were prepared and investigated by Limiting Oxygen Index(LOI)and Vertical Burning Test(UL-94),respectively.The results showed that the LOI value of EP composite with 5 wt% PFCTR(FR-3)reached28.3,and achieved a UL-94 V-1 rating.there was almost no flame retardant effect for EP with only 4 wt% APP(FR-7).However,when the total addition content was 4 wt%,combining 0.5 wt% PFCTR and 3.5wt% APP,the LOI value of EP composite(FR-10)reached 30.5 and a UL-94 V-0 rating could be achieved.This phenomenon indicates that there absolutely exist a synergist effect between PFCTR and APP.CONE data showed that heat release rate(HRR),smoke production rate(SPR)and the CO production rate of FR-10 decreased largely compared to pure EP.Finally,the thermal decomposition process and flame retardant mechanism in the gas phase and the condensation phase of flame retardant EP systems were further discussed by TG-IR.The results showed that more char residue was formed for FR-10 system.The non-flammable gas from the burning of FR-10,including CO2,CO,NH3,H2C=NH and aromatic compounds,etc,can dilute the concentration of oxygen and improve the fire retardancy of EP.In addition,the morphology of char layer after CONE test was observed by SEM in detail.The results demonstrated that the outer char surfaces of FR-10 system are the most compact and smooth among all three flame retardant EP systems,which can effectively block the transmission of heat and oxygen. |
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