Synthesis Of Composite Flame Retardant Containing Sulfur,Nitrogen And Phosphorus And Research Of Its Flame Retardancy On PC

Polycarbonate(PC)is one of the most important engineering plastics due to its outstanding properties,it is widely used in all areas of the national economy.But the PC belong to flammable materials and its UL-94 rating is typically V-2.It is easy to cause a fire when PC combustion dripping melt.In order to meet the higher requirement of PC in some special areas,PC has often been flame retarded.Presently,among the most flame retardants of PC,some high efficiency halogencontaining flame retardants have been gradually replaced by halogen-free FRs which are highefficiency and environment-friendly owing to environmental concerns.The combination of multiple elements has become a hot research topic in the field of halogen-free flame retardants.On the basis of multielement synergistic flame retardant,the following were mainly studied in this paper:(1)A novel composite flame retardants of SNP containing sulfur,nitrogen and phosphorus was synthesized from amino benzene sulfonic acid,maleic anhydride and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO).Its chemical structure was confirmed by ESI-MS and FTIR.The TGA showed that SNP had good thermal stability and good charring-form.(2)The SNP was blended with PC to prepare a series of PC/SNP composites via melt blending.The flame retardancy and thermal degradation behavior of the PC/SNP composites were investigated by limiting oxygen index(LOI),vertical burning test(UL-94),cone calorimeter and TGA.The results showed that the LOI value of PC/SNP systems could reach a maximal value of 34.5% when the content of SNP was 0.1%,and the UL-94 rating reached V-0.The PC matrix still maintain the mechanical properties of virgin polymer when the adding amount of SNP was less than 0.25%.The peak heat release rate(PHRR)and peak smoke produce rate(PSPR)of PC/SNP(0.1%)composite were decreased by 21.1% and 25% compared with PC,and the gas phase and condensed phase mechanism are existed all the time.The addition of SNP could reduce the initial decomposition temperature of virgin PC,promote the formation of carbon layer.The kinetics of thermal decomposition was evaluated by Kissinger and Flynn-Wall-Ozawa methods,the results showed that SNP could increase the thermal decomposition activation of virgin PC,and improved the thermal stability of the PC.The morphology of the chars remaining after the LOI test was studied by FTIR and SEM,the results showed that SNP could improve the surface of PC/SNP(0.1%)system form more fluffy and continual residual char layer.The char could efficiently inhibit oxygen transmission and heat diffusion during combustion,and therefore attributed to increase the flame retardancy.