| Polyamide (PA) is an important engineering resin, which widely used in fiber, automobile manufacture and electric appliance. Glass fiber reinforced PA66 is widely used because it has high intensity, dimensional stability and chemical corrosion-resistance and so on. But the disadvantage of flammability restricts its application in some fields, especially in the fields of electron and communication. So thermal stability and fire resistance properties of glass fiber reinforced PA66 are always considered first.In this paper, metal ion modified melamine phosphates (M-MPP) were synthesized using melamine, phosphoric acid and metal oxides as raw materials and distilled water as the solvent. Then the new flame retardants-metal ion modified melamine polyphosphates were polymerized by metal ion modified melamine phosphates at 300℃. The molecular structures of flame retardants were characterized by means of 'Quimociac' and atom absorption spectrophotometry, and the content of phosphorus, zinc ion, cupric ion and magnesian ion was 12.8%, 1.86%, 1.79% and 0.72%, respectively. And their thermal degradation was determined by thermogravimetry analysis. The results showed that the thermal stabilities of new flame retardants were better than that of melamine polyphosphate (MPP). In addition, their crystal structures were characterized by X-ray diffraction and scan electron microscope, and Zn-MPP was needle-shaped crystal, MPP, Cu-MPP and Mg-MPP were all flaky crystals.M-MPP/GFPA66 composites were prepared by using PA66, glass fiber, flame retardants and the processing agent as raw material with different ratio by means of twin screw extruder and inject machine. And mechanical properties, structures, thermal degradation, flame retardancy, and non-isothermal crystallization behaviors of the composites were measured and characterized.The data of mechanical properties showed that M-MPP reduced tensile strength, flexural strength and Notched Izod impact of PA66 composites. The mechanical properties of composites varied with the contents of M-MPP. And the mechanical properties of MPP/GFPA66 changed unobviously with the increase of MPP; however, those of Zn- MPP/GFPA66 and Cu-MPP/GFPA66 were first enhanced, then reduced with the increase of Zn-MPP and Cu-MPP, whose mechanical properties were best when the contents of Zn-MPP and Cu-MPP were 20%; those of Mg-MPP/GFPA66 were reduced with the increase of Mg- MPP. In particular, KH550 modified Zn-MPP made the composite have excellent mechanical properties. The SEM demonstrated that MPP and Mg-MPP were dispersed in the composites unevenly, and even reunited. Compared with the dispersion of MPP and Mg-MPP, those of Zn- MPP and KH550 modified Zn-MPP were better, and KH550 modified Zn-MPP could improve the compatibility with GFPA66 greatly. However, compatibility of Cu-MPP and GFPA66 was the best, and paricles of flame retardant-Cu-MPP were not seen.The results of flame retardancy indicated that the levels of flame retardancy of composites which thicknesses were 1.6mm all reached UL94V-O when the contents of flame retardants were 25%, and flame-retardance performances of Cu-MPP were the best of them. However, the composites which thicknesses were 3.2mm reached UL94V-O and the limited oxygen index was 34.2 when the contents of flame retardants were 20%. The flame-retardance performances of them from good to bad were Cu-MPP, Zn-MPP, MPP and Mg-MPP in turn. TGA results indicated that flame retardants made the temperature of initial decomposition appear earlier and increased the char residues of GFPA66 composites.Non-isothermal crystallization study demonstrated that flame retardants acted as nucleating agents in the GFPA66 and enhanced the crystallization of composites. The crystalline degree of Zn-MPP/GFPA66 was higher than those of MPP/GFPA66 and other M- MPP/GFPA66. Avrami's method was suitable for investigating the non-isothermal crystallization process of composites, however, Liu's method was not.
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