| Intumescent flame retardant(IFR) is widely used in polypropylene(PP) flame retardant because of its halogen- free, low smoke and low toxicity. It is mainly composed of acid source, carbon source and gas source, which can interreact with each other to ge nerate swelling char covered on the surface of marerial. The char plays an important role on the flame retardant of PP, it can isolate the heat and oxygen, and also stop the escape of the combustible gas. However, the flame retardant efficiency of traditional IFR containing polyols as charring agent is not satisfied. No less than of 25wt% addition of IFR was needed to achieve good flame retardant property. So the research of new charring agent is acted as one of feasible ways to improve the flame retardant efficiency of IFR. Recent studies have shown that triazine compounds present excellent carbon formation effect in IFR. Our work will focus on the research of new triazine-based charring agent. Furthermore, addition of IFR alone is hard to play its best flame retardant efficiency, so it is need to synthesis one kind of synergist to modify its performance.In this paper, three kinds of triazine-based charring agent(C YM, C DP and CYP) were synthesized from cyanuric chloride, morpholine, piperazine and diethanol amine. Their structures were characterized by infrared spectroscopy(FT-IR) and nuclear magnetic resonance spectrum(NMR). The thermal stability was tested by thermo-gravimetric analyzer(TGA). TGA tests suggest that their thermal degradation temperature are higher than 200 oC and suitable for the processing of polypropylene(PP). The thermal stability of CDP and C YP are better than that of CYM, in addition, the char residue at high temperature are higher too. The charring agents and ammonium polyphosphate(APP) were used as intumescent flame retardant(IFR) into polypropylene. The results reveal that, all kinds of IFR containing of APP and charring agent at mass ratio of 2:1 have good flame retardance efficiency in PP, the total addition of IFR are 25 wt%, 20 wt% and 17 wt% respectively, PP composites achieve the UL94 V-0 level and have LOI value of 30.6%, 29.5% and 29.5%.In order to further improve the flame flame retardance efficiency of IFR, we try to research one kind of synergist. Considering the synergistic effect flame retardant of the nickel(Ni) and montmorillonite(MMT), an exfoliated montmorillonite(M-MMT) was prepared by introducing N i2+ and melamine formaldehyde resin into layers of MMT through ion exchange and in situ intercalation. We systematically studied synergism effect of E-MMT in charring agent of CYM system. The results indicate that E-MMT can make PP pass the UL94 V-0 test with 16 wt% IFR and 3 wt% M-MMT while the addition of single IFR is no less than 25 wt% to achieve the same UL-94 level. O vermuch addition of M-MMT will damage the flame retardant property. The TGA results indicated that M-MMT promotes the degradation of IFR and PP/IFR composites at low temperature of IFR and PP/IFR composites but improves the char residue. The result from the Cone test show M-MMT helps to reduce of the heat release rate(HRR) and the total heat release(THR), also promote the generation of swelling carbon layer and increase the amount of carbon layer. The morphology of char layers were also studied by scanning electron microscope(SEM), it reveals that the outside structure of char layers were changed loosen and micropores by M-MMT. However it was just attributed to the intumescent inside structure and a microporous outside structure of char, can provide the efficiency protection of the matrix. FT-IR of char suggests the chemical structure of char was not destroyed by M-MMT. In general, M-MMT can promote the quality and quantity of char, therefore, a high efficiency of flame retardancy is achieved. As to CDP and CYP system, M-MMT can reduce the total addition of CDP system to 18 wt% with addition of 1 wt% M-MMT to achieve UL94 V-0 level, while there is no obviously s ynergism effect on C YP system. |
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