Preparation And Properties Of In-situ Polymerization Nanomaterials Flame Retardant Synergistic System Nylon 66

Nylon 66(PA66)is an important engineering plastic.However,its flammable and easy to drip limitations limit its application in many fields.Therefore,improving flame retardancy has become the necessary research and development direction of pa66.Halogen flame retardant is gradually replaced by phosphorus flame retardant due to its high toxicity.Phosphate ester has good flame retardant effect on PA66.The preparation method can be divided into blending method and copolymerization method.Disadvantages,wherein the copolymerization method is to polymerize the flame retardant monomer to the main chain of the material by chemical copolymerization,so that the composite material itself has flame retardant property,and the durability of the composite material is good,but the steric hindrance of the flame retardant monomer is generally compared.Large,increasing the difficulty of polymerization,and achieving the flame retardant effect,the addition amount is usually more,and the preparation process is more complicated,and the prepared composite material has lower viscosity,which affects its mechanical properties.At this time,a flame retardant effect can be achieved by adding a synergist together with a phosphorus-based flame retardant.The addition of nanoparticles as a synergist to a polymer to prepare a composite imparts some superior properties to the material.For example,nanoparticles can enhance the flame retardant properties of materials and evolve over time.Nanoparticles have become an effective alternative to traditional flame retardants.CPPOA when flame retardant PA66 is prepared by using CPPOA[4-(2-(((carboxy))(phenyl)phosphoryl)oxy)ethoxy)-4-oxohexanoic acid]When the addition amount is 6 wt%,the flame retardant performance reaches V1 grade,and the mechanical properties decrease less.When the content of CPPOA increases to 8 wt%,the flame retardant grade reaches V0 grade,but its mechanical properties will be greatly reduced.This has led to a significant decline in the applicability of materials.In this paper,the synergistic effect of granular nano-silica(SiO2)and layered montmorillonite(MMT)and flame retardant CPPOA were selected to modify the flame retardant of PA66 by in-situ polymerization.When the amount of flame retardant CPPOA added is 6 wt%,it is synergistically compounded to improve the flame retardant grade of flame retardant PA66 to V0 and improve the mechanical properties of the material.In this paper,the preparation process of flame retardant PA66 was explored,and the flame retardant properties,combustion behavior,flame retardant mechanism,crystallization properties and mechanical properties of the modified polymer were studied.The specific research results are as follows:The test results of the limiting oxygen index and UL-94 grade flame retardant performance show that when the addition of flame retardant CPPOA is 6 wt%,the limiting oxygen index reaches 25.7,the flame retardant grade reaches V1 grade,and the co-effector nano-oxidation is added.The limit oxygen index of silicon increased to 27.2,and after adding the synergist montmorillonite,the limiting oxygen index increased to 27,and the flame retardant grade reached V0.At the same time,the flame retardant PA66 with 6 wt%flame retardant added with 6 wt%flame retardant CPPOA and 1 wt%nano silica synergist was added,and the limiting oxygen index was increased by 1.4.PA66,which only added 1 wt%nano-silica synergist,had a limiting oxygen index of 0.5 compared to pure PA66.The increase in the limiting oxygen index of the former is more obvious,indicating that there is a significant synergistic effect between the synergist and the phosphate.The results of microcalorimeter test showed that the addition of synergist(MMT,SiO2)in the phosphate ester system showed a significant decrease in heat release,heat release rate and heat release capacity,indicating that the synergist had better Assist in the role of flame retardant.The results of thermal degradation analysis showed that the addition of synergist(MMT,SiO2)significantly increased the residual carbon ratio of flame retardant PA66,and delayed the maximum heat release rate,causing it to move toward high temperature.Thermogravimetry-infrared(TG-IR),scanning electron microscopy(SEM),mapping,Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),differential scanning calorimetry(DSC),etc.The analytical method was applied to analyze the flame retardant mechanism and crystallization properties of flame retardant PA66 materials.The results showed that the synergist(MMT,SiO2)promoted the formation of carbon 66 into carbon,which made the carbon layer more dense and thus had more flame retardant phosphorus.The element remains in the condensed phase,which better achieves the flame retardant effect.And the synergist(MMT,SiO2)increases the melt crystallization temperature and crystallinity of the flame retardant PA66.The mechanical properties test results show that the synergistic effect(MMT,SiO2)is introduced into the flame retardant system,and the mechanical properties of the material are improved compared with the single plus CPPOA.