The flame retardant and smoke suppressant effect of transition metal hydroxystannate (MSn(OH)6, M = Fe, Co, Mn) for epoxy resin

Perovskite hydroxystannate (MSn(OH) 6 ) has garnered considerable interest in recent years as a novel flame retardant characterized by its low toxicity and environmentally benign properties. In order to improve the flame retardancy and smoke suppression properties of epoxy resin (EP) matrices, transition metal hydroxystannate (MSn(OH) 6 , M = Fe, Co, Mn) was prepared by a ultrasonic-coprecipitation method and used as flame retardants. The synthesized composites were assessed for their flame retardant characteristics and mechanical properties through the measurement of the limiting oxygen index (LOI), the cone calorimetry test (CCT), and universal tensile testing. Upon the incorporation of 10 wt% of the MSn(OH) 6 flame retardants, the flame retardant of EP composites exhibited marked enhancement, especially manganese hydroxystannate (MHS). Compared with pure EP, the EP/MHS-10 composite demonstrated the best performance, reducing the peak of heat release rate (pHRR), total heat release (THR), total smoke production (TSP) by 60.0%, 14.4%, and 32.6%, respectively. During the process of combustion, the decomposition of MSn(OH) 6 results in the generation of non-flammable gases and water vapor. In the condensed phase, tin (Sn) and transition metals contribute to the formation of a more protective char residue. The residue serves as a physical barrier, effectively isolating the underlying epoxy (EP) matrix material from heat and oxygen.