Synthesis And Application Of Cyanuric Chloride Based Intumescent Flame Retardant Containing Nitrogen And Phosphorus

Intumescent flame retardants(IFR)are a class of environmentally friendly halogen-free flame retardants with low smoke,low toxicity and anti-melt-drop characteristics.Usually their components include carbon source,acid source and gas source,and IFR interacts with the polymer matrix to form a thermally stable protective carbon layer during the combustion process to achieve flame retardancy.In this thesis,in response to the problems of low flame retardant efficiency and large addition of traditional intumescent flame retardants,several IFR systems were prepared by preparing a new structure of carbon source and adding co-effectors,etc.The flame retardant effect and mechanism of IFR in polymer matrix were investigated in detail.The main findings of the study include:(1)The carbon source of conventional IFR is usually polyhydroxy compounds,which have good char formation properties but suffer from low efficiency,large addition quantity and non-renewable.The phosphorus-nitrogen star-forming char agent BTETP was synthesized by a series of nucleophilic substitution reactions using triethyl phosphate,ethylenediamine and melamine as the main raw materials,with a regular product structure,abundant phosphorus and nitrogen elements and high yields.The optimal synthesis conditions of BTETP were explored by the multi-factor level orthogonal test method.The structure of BTETP was verified as expected using infrared spectroscopy(FTIR),nuclear magnetic(NMR)and elemental analysis(EA),and the thermogravimetric analysis(TGA)results showed that BTETP has good thermal stability as well as char formation,and can be considered as a good char source.(2)The IFR system was composed of BTETP as the carbon source and APP as the acid and gas source,and the effect of IFR addition amount and proportion on the flame retardant properties of flame retardant PP composites was studied.The results showed that IFR has less addition and better flame retardant properties than the conventional PER/APP system.The PP/IFR composites showed the best flame retardant performance when the ratio of BTETP to APP was 2:1,and the composites passed the UL-94 V-0 rating with only 20 wt.% added flame retardant without melt drops.In addition,the flame retardant of IFR was discussed.The addition of IFR changed the pyrolysis process of PP,and the interaction between the decomposition products of IFR and PP occurred during the combustion process,so that PP remained more in the form of condensed phase in the residual char;IFR had good char formation,forming a dense and complete char layer,which effectively protected the internal matrix material.(3)To improve the flame retardant efficiency of IFR,aluminum diethyl hypophosphite(ADP)was used as a co-effector,and the synergistic enhancement of ADP on IFR was investigated.The effect of the amount of ADP on the synergistic effect was discussed in PP/IFR composites.It was found that ADP could effectively enhance the flame retardant efficiency of IFR when replacing APP with 2 wt.% of ADP,and the composite passed UL-94 V-0 level with no melt drops at the addition amount of 17 wt.%.The results show that the decomposition products of ADP migrate to the surface of the char layer during combustion,enhancing the thermal stability of the char layer and promoting the formation of more high-quality char layers.