Aluminium tri-hydroxide (ATH) powder was tested at 0 – 15% loading in epoxy resin (E51) in 4 mm sheets. Peak heat release rate was reduced by nearly 30% by 15% ATH compared to neat epoxy, total smoke release was reduced by nearly 18% and carbon monoxide production rate reduced by over 30%. The FR and smoke suppressant effects of ATH are the result of release of water, which decreases flammable gases and inhibits combustion, and of the production of an Al2O3 film on the epoxy surface, improving charring, so reducing combustion and reducing smoke release. However, the 15% ATH loading caused a significant loss of mechanical performance of the epoxy (>50% reduction in tensile strength).
“On improving flame retardant and smoke suppression efficiency of epoxy resin doped with aluminum tri-hydroxide”, G. Chai et al., Advanced Composites Letters, Volume 28: 1–12, 2019 https://doi.org/10.1177/2633366X19894597