Flammability of cis-1,4-polyisoprene vulcanizates

Antimony trioxide, chloroparaffins, Sb2O3-chloroparaffin mixtures, pentabromotoluene, and melamine cyanurate were examined as flame retardants for cis-1,4-polyisoprene (Cariflex-IR 307) peroxide vulcanizates. The oxygen-index method was used to test flammability in oxygen and in air (Table 2). The temperature of ignition was determined (Table 3) and the distribution of temperatures was ascertained along the length of the sample burning in air. Antimony trioxide alone was entirely inefficient as flame retardant; chloroparaffin was efficient, also when mixed with Sb2O3 as synergist. The vulcanizates containing chloroparaffin-Sb2O3 went out in 45-137 s after the ignition flame had been removed. Melamine cyanurate and pentabromotoluene were most efficient, the latter allowing vulcanizates to be prepared that went out in air immediately after the igniting flame had been removed.