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. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 47367.