Structure–property relationship in intumescent polymeric formulations containing waste zeolite-based material as a synergistic agent

The synergistic effect between spent oil-cracking catalyst (FCC catalyst) and an ammonium polyphosphate/pentaerythritol intumescent mixture was evaluated for various polyethylenic matrices. The mixtures were rated according to the UL-94 standard and evaluated by limiting oxygen index (LOI) testing, Thermogravimetric analysis and cone calorimetry. LOI results demonstrated a synergistic effect of the catalyst with the intumescent formulation in polyethylene, poly(ethylene-co-butyl acrylate), poly(ethylene-co-ethyl acrylate), poly(ethylene-co-methyl acrylate) and poly(ethylene-co-butyl acrylate-co-maleic anhydride). This synergistic effect also led to lower rates of heat release, total heats evolved and fume emissions, as observed by cone calorimetry. The nature of the polymeric matrix appears to influence the extent of the synergistic effect and, among the comonomers studied, butyl acrylate seems to benefit the most from catalyst addition in terms of fire-retarding properties. Apparently, the amount of comonomer affects the LOI results, although its influence as measured by other tests is not clear.