Preparation And Study Of High Efficiency Intumescent Flame Retardant Polypropylene Nanocomposites

Polypropylene is one of the five general-purpose plastics,but it is extremely easy to burn,so the promotion and application of polypropylene cannot be separated from the development of flame retardants.Intumescent flame retardant is an environmentally friendly flame retardant,which has the advantages of low smoke,low toxicity,and non-corrosive gas.However,as the amount of addition increases,the mechanical properties of polypropylene deteriorate.In order to improve the flame retardant efficiency of the expanded flame retardant and reduce the amount of addition,aiming at the special flame retardant mechanism of expanded flame retardants,this paper prepared organic layered silicate synergistic expansion flame-retardant polypropylene composite material and studied the following:First,16 groups of organically modified sodium-based montmorillonite were prepared by a microwave stripping process,and then an organic montmorillonite synergistic expansion flame-retardant polypropylene composite material was prepared by a melt blending method.The effects of microwave stripping process and organic montmorillonite on the thermal stability and crystallization properties of composites were studied,and their combustion properties were tested.Finally,montmorillonite was explored by Fourier transform infrared spectrometer,scanning electron microscope,energy spectrum analyzer,etc Soil organic modification effect and micro-morphology of composite materials,The results show that the organic modification of montmorillonite can be effectively promoted under a certain microwave stripping process.The addition of organic modified montmorillonite can effectively reduce the maximum thermal degradation rate of the composite material and increase the amount of residual carbon,and can increase its crystallization rate and crystallinity.3 wt% organically modified montmorillonite can effectively improve the thermal stability and crystallization properties of the composite material.The limit oxygen index of the composite material reaches the flame retardant standard.The UL-94 flame retardancy test is V-1 level.Second,the non-isothermal thermal degradation kinetics and non-isothermal crystallization kinetics were used to study the dependence of the thermal stability and crystallization properties of polypropylene and its composites on factors such as time and heating rate,the results show that: Organic montmorillonite can improve the thermal stability of composite materials,and the expansion flame retardant can effectively increase the activation energy of polypropylene.Excessive cooling rate can lead to imperfect polymer crystallization.Expanding flame retardants can reduce the crystallization rate and crystallinity of polypropylene.Organic montmorillonite can increase the crystallization rate and crystallinity of composite materials.Third,four different organic modified layered silicates were prepared by microwave stripping process,and organic layered silicate co-expanded flame retardant polypropylene composites were prepared by melt blending.The thermal stability,crystallization and combustion properties were studied,and the organic modification effect of montmorillonite and the micro-morphology of polypropylene composites were investigated by Fourier transform infrared spectrometer,scanning electron microscope,energy spectrum analyzer,etc.The results show that : Microwave stripping process can effectively promote the organic modification of hydrotalcite,clay,vermiculite and kaolin.Under the same content and microwave stripping process,only the organic vermiculite and organic kaolin can improve the thermal stability of the composite.All four organic layered silicates can improve the crystalline properties of the composites,and the limiting oxygen index has reached the flame retardant standards.Among them,organic vermiculite,organic clay,and organic kaolin have significantly improved the combustion performance of the composite.The UL-94 flame retardant test is V-1 level,and the organic-type hydrotalcite-expanded flame retardant polypropylene composite UL-94 test is HB level.