The Preparation Of Halogen-free Flame Retardants

As polymer materials has been used more and more widely in common life, it is important to improve the fire retardancy of it. Though the classical halide flame retardants have good performance, most of them give out heavy smoke with poisonous gas when burning. The flame retardant is developing toward high efective, no halogen and light smoke in next years. The melamine salts(including melamine phosphate, melamine polyphosphate and intumescent flame retardant) is consisted of acid source and gas source and take the nitrogen and the phosphorus as valid compositions. When the flame retarded materials filled with these compounds are burned, the intumescent layer can insulate thermal , inhibit smoke and prevent producing molten drops, so the flame retarding performance is high. Besides, inorganic flame retardant is widely used for it' s persistent efect and innocuity .Melamine salt of pentaerythritol phosphate (PPM) and melamine polyphosphate of different polymerization degree were successfully synthesized by simple craft. Inorganic flame retardants with different morphologies , such as hydrotalcite,magnesium oxysulfate and magnesium hydroxide, were prepared by hydrothermal method. The influence of condition upon the products and thermal peoperty were discussed. the detailed information is listed as follows:1,PPM was synthesized taking phosphoric acid as phosphorus source and ethanol as medium. The preparation procee was optimized so that PPM had high intumescent degree and char yield. TG-DSC showed the product had big temperature scope of absorbing hot and good thermal stability. Melamine polyphosphate ( MPP1 ) was synthesized from melamine and polyphosphoric acid in ethanol and melamine polyphosphate (MPP2) was prepared by hydrothermal method using melamine and phosphoric acid. The products were characterized by XRD, TEM, TG and DSC. The results showed that they had good thermal stability and MPP2 had higher crystallinity than MPP1.Both the polymerization degree and the temperature at which MPP2 started to decompose went up as the increase of hydrothermal temperature.2,Hydrotalcite was synthesized by hydrothermal method using the urea as a preeipitiant and the process of hydrotalcite' s formation was discussed. XRD analysis showed that the product had high crystallinity . Organic anions were intercalated into hydrotalcite by using sodium dodecyl sulfate(SDS) and interlayer spacing increased from 0.76 nm to 2.64 nm. TG-DSC showed hydrotalcite absorbed much more heat before intercalation.3,By adjusting conditions , the morphologies of magnesium oxysulfate could be controlled as fiber-like, bundle-like and rod-like. Rod-like magnesium hydroxide was prepared by using fiber-like magnesium oxysulfate as precursor and nanoplate-like magnesium hydroxide which had fine filtering property was obtained by adding SDS in hydrothermal method. TG-DSC showed that the products had excellent thermal stability. The thermal decomposition kinetics of magnesium hydroxide was studied by Freeman-Carroll method.The apparent activation energy of magnesium hydroxide prepared by hydrothermal method was obviously increased.