Thermal behavior and flammability of epoxy/glass fiber composites containing clay and decabromodiphenyl oxide

Epoxy/glass fiber hybrid composites with organo-montmorillonite (OMMT) and decabromodiphenyl oxide (DBDPO) flame retardants were prepared by vacuum-assisted resin infusion technique. The effects of OMMT and DBDPO on the flammability properties of epoxy/glass fiber hybrid composites were evaluated through UL-94 vertical flammability test and limiting oxygen index (LOI). Thermal decomposition was studied by means of thermogravimetric analyzer (TG). Field emission scanning electron microscopy (FESEM) was used to study the char morphology of the epoxy hybrid composites after being subjected to UL-94 vertical flammability test. Epoxy/glass fiber/OMMT hybrid composites with DBDPO loading of 40 wt% showed V-1 rating, whereas an increase to 50 wt% loading showed V-0 rating. The LOI values increased from 22.7 to 39.9 % as the loading of DBDPO increased. The obtained TG results showed that the thermal stability of epoxy hybrid composites decreased as the DBDPO loading increased. DBDPO decomposed at a lower temperature to form bromine radicals, which reacted with the combustible gases to form hydrogen bromide to inhibit the flame spread in the gas phase. The condensed phase activity was shown in FESEM, in which a layer of compact and continuous char was formed in epoxy/glass fiber/OMMT/DBDPO hybrid composites.