Combustion Behavior of Intumescent Flame Retardant Polypropylene Composites

The combustion behavior of polypropylene (PP) composites containing intumescent flame retardant additives, i.e., melamine pyrophosphate (MPP) and 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane (PEPA) was characterized by limiting oxygen index (LOI), UL 94 and the cone calorimeter. It has been found that the PP composite containing only PEPA does not show good flame retardancy even at 30% additive level. Compared with the PP/PEPA binary composite, the LOI values of the PP/PEPA/MPP ternary composites at the same additive loading are all increased, and UL 94 rating of the ternary composite (PP3) studied is raised to V-0 from no rating (PP/PEPA). The cone calorimeter results show that the heat release rate and mass loss rate of some ternary composites decrease in comparison with the binary composite.