Flame-retardant additives and comonomers slow the ignition or the spread of a fire in a polymer. Four general mechanisms are distinguished: gas-phase radical scavenging, condensed-phase char formation, dilution by an inert filler, and physical cooling by an endothermic decomposition [1]. Halogenated compounds act in the gas phase and are efficient at low loading, but their combustion products are corrosive and persistent, which has driven substitution [2]. Phosphorus-based systems favour char and are the main alternative for engineering thermoplastics [3]. Intumescent formulations combine an acid source, a carbon source, and a blowing agent, so the coating expands into a foam that insulates the underlying material [4]. The additive normally degrades the mechanical properties, and the balance between the loading needed for a fire rating and the property loss is the central design problem [5].
- char formation
- intumescent
- halogen-free
- gas-phase radical scavenging
- phosphorus additive
- limiting oxygen index
- endothermic decomposition
References
- Yang, S.; Wang, J.; Huo, S.; Cheng, L.; Wang, M.; Preparation and flame retardancy of an intumescent flame-retardant epoxy resin system constructed by multiple flame-retardant compositions containing phosphorus and nitrogen heterocycle. Polymer Degradation and Stability 2015, 119, 251-259, 10.1016/j.polymdegradstab.2015.05.019.
- Yu, H.; Xia, Y.; Xu, X.; Zarshad, N.; Wu, M.; Ni, H.; Preparation of organic–inorganic intumescent flame retardant with phosphorus, nitrogen and silicon and its flame retardant effect for epoxy resin. Journal of Applied Polymer Science 2020, 137, 49256, 10.1002/app.49256.
- Inprasit, T.; Niyomdacha, D.; Promchantuek, C.; Thangtong, T.; Vanichvattanadecha, C.; Pisitsak, P.; Sustainable Intumescent Flame-Retardant Coating with Sericin, Phosphorus, and Silicon for Polyester Fabrics. Polymers 2026, 18, 682, 10.3390/polym18060682.
- Wang, G.; Chen, X.; Liu, P.; Bai, S.; Flame‐retardant mechanism of expandable polystyrene foam with a macromolecular nitrogen–phosphorus intumescent flame retardant. Journal of Applied Polymer Science 2017, 134, app.44356, 10.1002/app.44356.
- Zheng, Z.; Liu, Bingnan Wang, Ting Yang, S.; Cui, X.; Wang, H.; Preparation of a novel phosphorus‐ and nitrogen‐containing flame retardant and its synergistic effect in the intumescent flame‐retarding polypropylene system. Polymer Composites 2015, 36, 1606-1619, 10.1002/pc.23069.