The Formulation of Nonburning Elastomer Compounds

In this investigation the flammability of 34 polymers was evaluated in 68 compounds; 28 flame retardants were tested in 275 compounds. Only two of 34 polymers evaluated as black-filled compositions were nonburning in the initial screening, five were self-extinguishing, and the rest were completely combustible. Twenty-three of the 32 combustible and self-extinguishing polymers were reformulated into nonburning polymers by the addition of two flame retardants—antimony oxide and either Chlorowax 70 or Dechlorane 515 (Table XIII). Frequently a plasticizer was required. If Chlorowax is compatible with the polymer, it often acts as a plasticizer. Fyrol FR—2 was the only other plasticizer found to be compatible with most polymers and permitting them to retain their nonburning classification.