Furfural-based P/N/S flame retardant towards high-performance epoxy resins with flame retardancy, toughness, low dielectric properties and UV resistance

The development of high-performance EP composites with high glass transition temperature (Tg), excellent flame retardancy, and UV resistance is a challenging topic in the flame retardancy community. In this work, a bio-based phosphorus/nitrogen/sulfur (P/N/S) containing flame retardant (FDI) was prepared from furfural, 2-amino-5-nitrothiazole, and DOPO. It was applied to improve the flame retardant, dielectric, and UV-resistant properties of EP. Thanks to the combination of phosphorus, nitrogen, and sulfur in FDI, the EP/FDI composites showed superior flame retardancy. Only adding 5 wt% FDI made EP achieve UL-94 V-0 flammability rating with a limiting oxygen index (LOI) of 27%. Meanwhile, EP/FDI-5% composite showed significant reduction of 65.1% and 33.6% in total smoke production (TSP) and the peak heat release rate (pHRR), respectively. The flame-retardant mechanisms of EP/FDI thermosets were investigated by residual char photographs, SEM, XPS, and Py/GC-MS. Moreover, compared to pure EP, EP/FDI composites showed excellent UV resistance, low dielectric properties, and high glass transition temperature, which was expected to be extensively used in multiple areas of production.