SynopsisThe role of lead compounds in blends of polyethylene and silicone has been studied as a flame retardant. It has been established that these compounds work in the solid phase and that a gas-forming reaction is important to produce a foamed char which retards further combustion.

Lead compounds and silicone gum when blended into polyethylene act as synergistic fire retardant. The incorporation of lead into the polymer network via lead carboxylate formation through polyethylene grafted with maleic anhydride has been studied as a means of improving the metal dispersion and flammability behavior. Lead was also incorporated directly into a polymer backbone via the formation of lead polyesters. The use of other metal compounds as fire retardant additives has also been studied. No special behavior was seen for polymer‐bound lead relative to non‐polymer bound lead, and other metals were not found to be effective replacements for lead in polyethylene graft maleic anhydride.