Impact of Aluminum Diethyl Phosphinate (DEPAL) Flame Retardant on the Thermal, Mechanical, and Fire‐Resistance Properties of an Amine‐Cured Epoxy Resin

ABSTRACT Epoxy resin systems are widely used in industrial applications due to their excellent mechanical and thermal properties. However, their inherent flammability restricts use in safety‐critical environments. To improve flame retardance, phosphorus‐based additives like aluminum diethyl phosphinate (DEPAL) are commonly used. This study focuses on evaluating the effectiveness of DEPAL in the form of the commercial particulate additive OP935 as a flame retardant in a fast amine‐curing epoxy resin system, EPIKOTE 06150. The incorporation of DEPAL significantly improves the flame retardance of the epoxy system, as evidenced by a reduced heat release rate and the Petrella plot. While OP935 improves flame retardance, its effects on other properties of the epoxy, such as mechanical strength and thermal stability, are also investigated. The results indicate that DEPAL may cause some reduction in flexural strength but does not negatively affect the thermal stability or glass transition temperature of the epoxy resin system. This balance between improved flame retardance and retained thermal properties suggests that DEPAL is a promising additive for the production of safer, more resilient epoxy resin systems suitable for various high‐demanding performance applications such as aerospace.