Synthesis Of Several Organophosphorus Flame Retardants And Research To Performance Of Flame Retard

Engineering plastic ASA, which is short for Acrylonitrile Styrene Acrylate copolymer, is the graft copolymer which is made of acrylate rubber, acrylonitrile and styrene. ASA is widely used in many fields of our society for its great physical properties. However, the flammability of unprocessed ASA is an obvious disadvantage. To solve this problem, flame retardants have to be added to the plastics to reduce losses. Currently, there are many types of flame retardants. The use of halogenated flame retardants is restricted because it releases Toxic gases, although the effect of halogenated flame retardants is the best one. The effect of inorganic flame retardants is not very ideal. The physical properties of the material will fall after add many inorganic flame retardants. The phosphorus-nitrogen flame retardants become the hot topic of the flame retardants study because they are working, environment-friendly and cost-effective.In this paper, the mechanisms of different types of flame retardants were discussed. Many developments of phosphorus flame retardants and nitrogen-based flame retardant were studied. Many previous synthetic routes were compared. To be more environment-friendly and cost-effective, three types of flame retardants were researched. They are pentaerythritol phosphate urea salt, neopentyl glycol phosphate melamine salt and starch phosphate melamine salt. Then, the preparation process of three types of flame retardants was optimized. FT-IR, TGA and the determination of phosphorus content were used to confirm the structures and determine if the prepared flame retardants were suitable for the ASA. Phosphorus content was measured under optimum conditions. Phosphorus content of pentaerythritol phosphate urea salt, neopentyl glycol phosphate melamine salt and starch phosphate melamine salt are 8.38%,9.90% and 5.54%, and the yield of them are 62.4%,50.3% and 53.6%. TGA curves of them showed that all decomposition temperatures were between 200℃ and 700℃, it is similar to the decomposition temperature of ASA. When the temperature reached 700 ℃, residual carbon rates of three kinds of flame retardants were more than 30%. It shows that their stability and char-forming ability was fine. All of them can be used in the ASA.Three types of prepared phosphorus-nitrogen flame retardants were added into the engineering plastic ASA by different mass fraction to test flame retardant. The method of the test is getting the limiting oxygen index (LOI) of the ASA, which were added some flame retardants. Then, the results were discussed and analyzed. It was concluded that all of three types of flame retardants is effective to the ASA. When the amount of the added flame retardants reached to 15%, the corresponding LOI had exceeded the amount of the oxygen in the air. When the adding mass fraction reached to 20%, the results were better. Then, the residual char was prepared by heating the flame retardants to 500℃ for 30min to analyze the mechanism of the flame retard. The residual char yield was more than 30%. The comparison of FT-IR. of original material and residual char, fluffy char showed that the flame retardants released many gases and the flame retardants acted in Gas and solid phase. The residual materials in the char contained P, N, O elements.