Flame-Retardant Properties And Flame-Retardant Mechanism Of Inorganic Nanoparticles Synergy Flame Retardant Polypropylene Composites

The research and application of polymer flame retardant composite are now gradually tending to be low smoke,non-toxic and efficient.Polypropylene(PP),as a widely used polymer material,is easy to burn and has serious droplets.It can be used by using Inorganic nanoparticles and highly efficient and environmentally friendly flame retardants are used to prepare PP flame retardant composites with excellent performance.In this paper,the flame retardants used in PP flame retardant composite materials are selected through experiments,and flame retardant composite with further research value are prepared.An inorganic nanoparticle graphene oxide was organically modified with phosphaphenanthrene flame retardant,and its chemical structure was characterized and analyzed.Using organic modified graphene oxide as a flame retardant synergist,and mixed with a quantitative flame retardant an inorganic nanoparticles synergistic PP flame retardant composite was prepared.The effect of the inorganic nanoparticles on the properties of PP flame retardant composites and the flame retardant mechanism were discussed.And further explore the flame retardant properties of a quantitative flame retardant content PP flame retardant composites prepared with organically modified graphene oxide and another kind of inorganic nanoparticles.The main work is as follows:1.Choose two halogen-free flame retardants to prepare PP flame retardant composite materials,one is a phosphaphenanthrene flame retardant called bridge chain 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(Di DOPO),the other is an expanded flame retardant(IFR)prepared by adding ammonium polyphosphate and dipentaerythritol.Two kinds of flame retardant composites of PP/Di DOPO and PP/IFR were prepared by adding Di DOPO and IFR of different additive amounts(0wt%,15wt%,18wt%,21wt%)to PP respectively.Through thermogravimetric analysis(TGA),vertical combustion(UL-94),limiting oxygen index(LOI),differential scanning calorimeter(DSC),mechanical property testing and other characterization methods were used,to compared of the two flame retardant composites thermal stability,flame retardancy,crystallization melting and mechanical properties.The test results show that the addition of both flame retardants can improve the thermal stability of the PP flame retardant composite;IFR has a good flame retardant effect,and when the amount is 18wt%,it can reach UL-94 V-Level 1 and the LOI value increased to 24.8%;The addition of both flame retardants can improve the crystalline properties of PP flame retardant composite,making PP flame retardant composite have good mechanical properties.2.Graphene oxide was modified with a phosphaphenanthrene flame retardant to prepare an inorganic nanoparticle,which is referred to as GODV.The structure and thermal stability of GODV were characterized by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance(NMR)and TGA.The test results show that GODV is successfully modified and has good thermal stability,and residual amount at 800 ? can reach 64.8%.Further adding different amounts of(0wt%,1wt%,3wt%,5wt%)GODV and quantitative(18wt%)IFR to PP to prepare PP/IFR/GODV flame retardant composite,through TGA,UL-94,Characterization methods such as LOI,Cone Calorimeter Test(CCT),Scanning Electron Microscope(SEM),Energy Dispersive X-ray Spectrometer(EDS)Energy,Thermogravimetry-Fourier transform infrared spectroscopy(TG-IR),Mechanical Properties Test,etc.The thermal stability,flame retardancy and mechanical properties were analyzed,and the mechanism of flame retardancy was discussed.The test results show that the addition of GODV will improve the thermal stability of PP flame retardant composites.The addition of GODV has a good synergistic flame retardant effect,when the addition amount is 1wt%,PP flame retardant composite material can reach UL-94 V-0 level,and the LOI value is 26.4%.CCT shows that GODV can effectively reduce the peak heat release rate(PHRR)and total heat release(THR)of PP flame retardant composites.Observation of the carbon layer by SEM shows that the addition of GODV can make the carbon layer more dense and complete.The mechanical properties test shows that the addition of GODV can effectively improve the mechanical properties of PP flame retardant composites.CCT,residual carbon and TG-IR test show that the addition of GODV has the function of forming carbon,mainly presents the mechanism of synergistically enhancing the flame retardant of the condensed phase,and also has the mechanism of enhancing the gas phase flame retardant.3.Further research was made on the properties of GODV and organic montmorillonite(OMMT)inorganic nanoparticles compounded in proportion to synergistic intumescent flame retardant PP,and the existence of synergistic flame retardation between the two inorganic nanoparticles was explored.The results show that when the total amount of filler is 20wt%,the compounding ratio of mass parts of GODV/OMMT is 1:1,and the thermal stability of PP flame retardant composites is slightly improved.The combination of the two inorganic nanoparticles can make the PP flame retardant composite material reach UL-94 V-0 level,and the LOI value of PP flame retardant composites increases to 28.0%.CCT shows that the combination of GODV and OMMT can reduce the PHRR value and the maximum heat radiation rate(MAHRE)value of PP flame retardant composite.Observation of the carbon layer through SEM found that the combination of GODV and OMMT can make the carbon layer more dense and complete.CCT,residual carbon and TG-IR tests show that OMMT can play the role of condensed phase and gas phase flame retardant in the matrix,so the flame retardant composite can have good flame retardancy after compounding.The mechanical property test shows that when the compounding ratio of GODV/OMMT is 1:1,PP flame retardant composite can have good mechanical properties.