A novel phosphorus – nitrogen chemistry PIN flame retardant was synthesised in a two-stage reaction from NPG (neopentylglycol): the phosphoramidate DPDA 2,2-dimethyl-1,3-propanediol-N,N-bis(2-hydroxyethyl).
Woven cotton (184 g/m2) was treated by soaking in DPDA solution for one hour, adding, drying and curing at hundred and 170°C, resulting in up to 25% add on weight DPDA. The PIN FR achieved around 50% reduction of PHR (peak heat release) and nearly 50% increase in LOI (limiting oxygen index), with self extinguishing and flame spread limited to 10 mm/s in a vertical burn test (vs. burn out for untreated cotton). TG-FTIR showed lower flammable volatile gas emissions from the treated cotton. The authors suggest that fire performance results from compact phosphorus rich char residue formation.
“A novel phosphoramidate and its application on cotton fabrics: Synthesis, flammability and thermal degradation”, B. Zhao et al., J. Analytical and Applied Pyrolysis 2017 http://dx.doi.org/10.1016/j.jaap.2017.04.011