Synthesis of a bio-based triazine derivative and its effects on flame retardancy of polypropylene composites

A triazine derivative CC-Cy was synthesized using cytosine (Cy) and cyanuric chloride (CC). The CC-Cy was used as a charring agent and combined with ammonium polyphosphate (APP) to form an intumescent flame-retardant (IFR) system. The IFR system was applied to improve the flame retardancy of polypropylene (PP). Moreover, bisphenol-A bis(diphenyl phosphate) (BDP) was introduced in the IFR system to regulate the suitability between the IFR and PP. The results showed the PP containing 20 wt % APP and 5 wt % CC-Cy achieves the UL-94 V-2 rating. While the PP with 18 wt % APP/CC-Cy (4:1) and 3 wt % BDP obtains the UL-94 V-0 rating indicating the improved flame-retardant efficiency. Thermal degradation behaviors and char morphology both showed that the reactions between APP and CC-Cy promote the formation of char residues, and BDP works in gas phase to enhance the flame retardancy of PP composites. Thus, a synergistic IFR system based on APP, CC-Cy, and BDP is formed, which can protect PP from fire effectively. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 47367