Azoalkanes: A novel class of flame retardants

The synthesis of azoalkanes such as azocyclohexane (1) and 4,4′-bis(cyclohexylazocyclohexyl)methane (2) and their use as flame retardants in polymeric substrates is reported. For the first time it is demonstrated that azoalkanes alone can effectively provide flame retardancy and self-extinguishing properties to poly(propylene) films at a very low concentration of 0.25 to 0.5 wt.-%. All the poly(propylene) formulations passed DIN 4102-1/62 standards and the instant azoalkane-containing poly(propylene) blends show no discoloration.