Synergism of triazine containing dopamine to flame retardancy, smoke suppression, and mechanical properties of thermoplastic polyurethane/ammonium polyphosphate

A dopamine-triazine compound (TTD) was synthesized by using dopamine and cyanuric chloride. The TTD and ammonium polyphosphate (APP) were combined to improve the flame retardancy of thermoplastic polyurethane (TPU). The flame retardancy, thermal stability and mechanical properties of TPU blends were investigated. TPU containing 8 wt% APP displays a UL-94 V0 rating and a limiting oxygen index (LOI) of 30.0 vol%. When APP and TTD are combined at a ratio of 7/1 (wt%/wt%), only 5 wt% flame retardant is needed to endow TPU with a UL-94 V0 rating, suggesting that a good synergistic effect exists between APP and TTD on enhancing flame retardancy of TPU. In addition, TTD reduces the heat release rate of TPU, suppresses the smoke and toxic gas release and promotes the formation of an intumescent char layer with few defects during combustion. In addition, TTD improves the tensile properties of TPU/APP blends.