Study On Flame Retardant PC System With Cyclophosphazene

As an engineering plastic,Polycarbonate（PC）is widely used in construction,automobile,electronic and electrical fields because of its good mechanical properties,thermal stability and good transparent properties.However,the flame retardant rating of PC is only UL-94 V-2,and the drop phenomenon is serious during combustion combustion,which can’t meet the needs of high fire safety occasions.Therefore,it is particularly important to modify the flame retardant of the PC.Although traditional halogenated have high flame retardant efficiency,they cause harm to the environment and human body during combustion.Cyclophosphazene is a green and efficient flame retardant,and the side groups of chlorocyclic phosphazene can be easily replaced by other nucleophilic reagents to obtain functionalized phosphazene,which provides a possibility for the development of PC flame retardant system.In this work,two green and efficient additive flame retardants and a new flame retardant coating were prepared:HPCTP flame retardant;HCPCP flame retardant;EPFP-AA flame retardant coating.The structure of the synthesized flame retardant was characterized,and studied its performance and flame retardant mechanism of the new cyclophosphazene flame retardant PC system.The conclusions are as follows:（1）Three cyclotriphosphazene derivatives were successfully synthesized:hexaphenoxycyclotriphosphazene（HCPTP）;Hexacarboxyphe noxycyclotriphosphazene（HCPCP）;Functionalized phosphazene（EPFP）.Structural characterization was performed by ¹H-NMR,³¹P-NMR and FTIR,respectively.And three flame retardant systems were prepared:PC/HPCTP;PC/HCPCP;PC-EPFP-AA.（2）In the PC/HPCTP system,the addition of HPCTP slightly reduced the tensile strength and initial decomposition temperature of PC,improved the flame retardant performance of PC and the regularity of residual carbon,and effectively inhibited the pyrolysis of PC:When HPCTP was added in 14 parts,the tensile strength of PC/HPCTP composites decreased to 61.5 MPa.When the amount of HPCTP is 12parts,the initial decomposition temperature is reduced to 410.0°C,the residual carbon rate at 800°C is increased to 23.94%,the UL-94 test reaches V-0 level,and the LOI value is increased to 29.3%.HPCTP improved the regularity of PC residual carbon and reduced the absorption strength of PC pyrolysis product.（3）In the PC/HCPCP system,HCPCP added to slightly improve the tensile strength,flame retardant performance and regularity of residual carbon of PC,reduce the hazard of PC combustion,and inhibit the pyrolysis of PC:when the amount of HCPCP is 14 parts,the initial decomposition temperature drops to 393.1°C,the residual carbon rate increases to 22.7%,the UL-94 test reaches V-0 level,and the limiting oxygen index is 29.4%,while greatly reducing the heat release rate and heat release amount of PC during combustion.The addition of HCPCP effectively inhibits the pyrolysis of PC,and improves the regularity of PC residual carbon.（4）In the PC-EPFP-AA system,the increase in EPFP content can improve the flame retardant properties and adhesion properties of PC:when the mass fraction of EPFP is 25%,the adhesion strength between the EPFP-AA coating and PC is 0.42 MPa,and the UL-94 test grade of PC reaches V-0 and the LOI is 29.6%.After the water resistance test,the adhesion strength dropped to 0.28 MPa,the UL-94 test was reduced to V-1,and the LOI dropped to 28.5%.