A dynamical systems model of the limiting oxygen index test: II. Retardancy due to char formation and addition of inert fillers

Oxygen index methods are widely used to measure the flammability of polymers and to investigate the effectiveness of fire retardants. Using a dynamical systems model an oxygen index is identified with an extinction limit point. The action of the fire retardant is investigated by unfolding this bifurcation point with a suitable continuation parameter which reflects the mode of action of the additive. The fire retardant mechanisms that we consider are non-competitive char formation and dilution by addition of an inert filler. We investigate which types of material are best retarded by each mechanism.