Synthesis Of Carbon Agent And Flame Retardancy Of Continuous Glass Fiber Reinforced Polypropylene Composites

Because of high strength,high modulus and light weight,composite materials are widely used in various fields,especially in military fields such as aerospace and naval vessels.In this paper,based on the problem of continuous fiber reinforced thermoplastic composites in the practical application as the background,studied the continuous glass fiber reinforced polypropylene flame retardant.First of all,using pentaerythritol,phosphorus oxychloride,acetonitrile and melamine as the main raw materials,synthesis a macromolecule charring agent poly(4,4-diaminodiphenylmethane-1,3,5-triazine-dicyandiopentaerythritol phosphate)(PDTBP)and compounded with polyphosphate(APP,n ? 1000)into Intumescent Flame Retardant(IFR).Structural analysis and characterization were carried out by infrared(FTIR),scanning electron microscopy and thermogravimetric analysis(TGA).The results showed that the optimum synthesis conditions of PDTBP were acetonitrile as solvent,the reaction temperature of PEPA and cyanuric chloride and the reaction temperature after adding DDM were 45°C and 50°C respectively,the dropping time of acid-binding agent was 2s/d,The PDTBP synthesized under this condition has high purity and yield.The intumescent flame retardant IFR prepared by compounding PDTBP with ammonium polyphosphate at a ratio of m(PDTBP):m(APP)=1:2 has excellent thermal stability and carbon formation.Secondly,the flame retardant PP was prepared by mixing IFR with polypropylene particles in the molten state.The mechanical properties,heat resistance and flame retardant properties were studied.Can be drawn IFR content of PP tensile strength and bending strength are increased first and then decreased,it had little effect on the impact strength.The addition of IFR greatly reduces the thermal decomposition rate of the matrix,that is,the addition of IFR significantly improves the thermal stability of the matrix.Flame retardant PP with the increase of IFR content,the limit oxygen index increased significantly,and the vertical combustion grade increased,which could significantly reduce the heat release rate,total heat release rate,smoke generation rate and total smoke generation rate of PP.The combustion mechanism is that a large amount of chemical reaction takes place in the process of charring of the flame retardant,releasing water and reducing organic matter to form a phosphate ester and a carbon-containing carbon.The carbon layer can effectively block the matrix and the outside oxygen and energy transfer,thereby enhancing the flame retardant properties of the material.Finally,the IFR was applied to a 300 mm wide continuous glass fiber reinforced thermoplastic composite production line independently developed by the laboratory to prepare the flame retardant prepreg IFR/GF/PP.The prepreg was pressed into different thickness laminates by double steel band press to study its mechanical properties,water resistance and flame retardant properties.The results show that: IFR has little effect on the mechanical properties of continuous glass fiber reinforced polypropylene composites;the flame retardant has a smaller precipitation rate;the water resistance of flame retardants is better;and the IFR/GF/PP composites are burned vertically.In the IFR / GF / PP composite vertical combustion test found that the material cann't pass the UL-94 level,but IFR addition can significantly slow down the combustion of the material.The residuals of the IFR/GF/PP cone calorimeter were observed by SEM.It was found that the flame retardant could form a continuous and dense carbon layer on the surface of glass fiber,which could effectively eliminate the "wick effect" of fiber in the composite.