Structure Control Of Novel Halogen-free Flame Retardant Polystyrene And Research Of Its Performance And Mechanism

The application of polymer materials in daily life and industrial production is gradually expanding,and its flammability also makes it a huge potential safety hazard for people’s lives and properties.Therefore,the flame retardant research of polymers has become the focus of current researchers.Among them,polystyrene has become a key difficulty in flame retardant research because of its high flammability,dripability,and toxic smoke.Currently there are three main flame-retardant methods:design and development of new non-combustible polymers or replacing the flammable polymers with the non-flammable polymers;synthesis of additional flame retardants and mixing with polymer to meet the flame retardant requirements;using chemical reactions to prepare flame retardant polymer.Considering that the latter two methods are the main methods which are studied and applied in the flame-retardant academia and industry,this paper is based on an overview of the latest flame-retardant work and previous work results,based on physical blending and chemical reactions.Based on the princple of flame retardant method,flame retardant polystyrene,styrene copolymer and modified polystyrene were prepared by physical blending,copolymerization and modification,and their performance changes and related mechanisms were compared and studied.The main research work is as follows:1.Using phosphorus oxychloride,piperazine and PEP A as raw materials,a macromolec ular flame retardant PPAP with a condensed phase flame retardant mechanism was synthesized by dechlorination nucleophilic substitution reaction.After the structure was successfully characterized,the physical blend was physically blended.The way to add polystyrene to prepare flame retardant polystyrene.The thermogravimetric analysis was used to study the thermal stability of flame-retarded polystyrene.The combustion properties of flame-retarded polystyrene were characterized by micro calorimeter,limiting oxygen index and vertical combustion method.The results showed that PPAP reduced the initial of polystyrene.Decomposition temperature,increase its maximum decomposition temperature and char formation efficiency,and significantly reduce the heat release rate and total heat release of polystyrene,and the LOI value and UL-94 level of flame-retarded polystyrene have also been improved.Scanning electron microscopy and Raman spectroscopy were used to analyze the morphology of flame-retarded polystyrene carbon slag.The results show that PPAP increases the density of the carbon layer and can effectively block the transport of material and heat conduction.2.Using DOPO as raw material,a flame retardant monomer ADEA-DOPO with high phosphorus content was synthesized by Atherton-Todd reaction.The styrene copolymer SACP was obtained by copolymerizing styrene with free radical bulk copolymerization.The thermogravimetric analysis and differential scanning calorimetry test results show that the maximum decomposition temperature of SACP can be significantly improved when the glass transition temperature is not significantly reduced.The test results of MCC,LOI,and UL-94 indicate that the heat release of SACP is significantly reduced.The results of real-time infrared spectroscopy(RT-FTIR)and Thermogravimetric-infrared(TG-FTIR)show that the introduction of Adea-dopo can increase the carbon efficiency of polymer matrix,delay the decomposition of molecular chain,change the composition of the gaseous product of polystyrene pyrolysis,and exert its flame-retardant effect.3.Epoxy groups were inserted into the polystyrene molecular chains using glycidyl methacrylate and reacted with 4-hydroxypiperidine and dimethyl phosphite to obtain modified polystyrene MFR-PS.Thermogravimetric analysis,differential scanning calorimetry,MCC,limiting oxygen index test and vertical combustion method were used to test the thermal stability and combustion properties of polystyrene before and after modification.The results showed that polystyrene could be modified and treated.Increase the maximum decomposition temperature and char formation efficiency,reduce the heat release rate and total heat release,and increase the LO1 and UL-94 levels.The characterization results of TG-FTIR and RT-FTIR spectra show that the modified treatment enables polystyrene to form barrier carbon layer,reduce the concentration of flammable volatiles and improve its flammability.