Polyethylene Flame Retarded with Expandable Graphite and a Novel Intumescent Additive

A novel intumescent additive was synthesized by neutralizing 3,5-diaminobenzoic acid hydrochloride salt with ammonium dihydrogen phosphate. This compound, which melts at 257 degrees C, decomposes concurrently to release carbon dioxide gas. The flame retardant performance of this compound as a primary fire retardant and in combination with expandable graphite (EG) was evaluated by cone calorimetry. Cone calorimeter results showed that addition of 10 wt % EG alone lowers peak heat release rate (pHRR) of carbon black-pigmented polyethylene from 710 +/- 109 to 342 +/- 15 kW m(-2), whereas addition of 27 wt % of the novel intumescent lowered it to 400 +/- 16 kW m(-2). Combinations of these two additives were able to decrease the pHRR even further. Furthermore, the novel intumescent additive reduced the flame out time from 773 +/- 307 to 537 +/- 69 s although all other EG containing samples increased it. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40493.