| Brominated flame retardants are added to styrenic block copolymer TPEs to improve their flame resistance. However, many brominated flame retardant types are available with differing bromine content and chemical structures that influence their efficacy. In addition, different flame retardant synergists are available that may further improve performance. A 75 Shore A mineral oil/S-EB-S/polypropylene TPE was developed in which four different brominated flame retardants, in combination with either of two synergists, was evaluated at various loadings. Experiment results demonstrated that increased brominated flame retardant loading increased oxygen index and reduced the cone calorimeter measured average heat release rate (AHRR), peak heat release rate (PHRR), total heat evolved (THE), and average effective heat of combustion (average EHOC). Higher bromine content, particularly aliphatic type bromine, further improved these results in addition to the use of the synergist antimony oxide over zinc borate. In addition, phosphorus and bromine on the same molecule demonstrated a less than additive effect on flame retardancy. Finally, the higher loadings also increased the visible smoke generated as measured by total smoke released (TSR) and average specific extinction area (average SEA). |
