Use of a combination of phosphorous-containing epoxy resin and silica fillers for development of flame retardant thermoset polymer composites

In this paper, we report a method of preparation of ambient temperature curable phosphorous containing epoxy resin-based composites and their flame retardant behavior. The phosphorous containing resin, prepared by reacting the epoxy resin with 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), shows higher limiting oxygen index (LOI) in the cured state compared to the pure epoxy network. The LOI value is further enhanced due to the incorporation of phosphorous-containing silica, although the same remains unchanged when pure silica is added. The composites made with phosphorous-containing resin and pure silica exhibits UL-94 V-1 class rating whereas the same made with phosphorous-containing silica offers V-0 rating under UL-94 classification. This observation clearly indicates that the performance is enhanced when phosphorous in incorporated in the resin as well as in the inorganic reinforcing filler.