Four different nitrogen containing bases (adenine, guanine, cytosine and uracil) were tested as PIN flame retardant combinations with APP (ammonium polyphosphate) in polypropylene. APP was supplied by Presafer and the bases by Aladdin. These bases are the same molecules as naturally found in all living cells in genetic material (DNA, RNA).
Polypropylene containing 1-2% cytosine or uracil and 16-17% APP achieved UL94-V0, with no drip, and LOI of nearly 28% or higher (that is, fire performance comparable to 25% APP loading). Adenine and guanine were not so effective. The flame retardancy effect of the bases cytosine and uracil is identified to be due to char generation, with improved thermal stability of the char at high temperatures. Uracil also reduced the peak heat release rate and total heat release (PHRR, THR).
“Regulating effects of nitrogenous bases on char structure and flame retardancy of polypropylene/intumescent flame retardant composites”, ACS Sustainable Chemistry & Engineering, 2017, Z. Wang et al.,
http://dx.doi.org/10.1021/acssuschemeng.6b02712