Antimony trioxide (ATO) is used as a synergist in PVC and with brominated and chlorinated flame retardants.
Expandable graphite (exp. C) consists of black flakes, which expand 100 to 300 times at around 300 °C. An important application is its use as a flame retardant for seats in railways and aircraft.
Nanocomposites are organo-layered silicates with the ability to incorporate polymers between the layer structures by intercalation or exfoliation. They do not act as flame retardants on their own, but may, together with other flame retardants, enhance the charring and reduce the heat release of the polymer. The only commercial application to date is the cable sector.