Novel additive and reactive PIN FRs, containing phosphorus and sulphur, were synthesised from a bio-based phenolic compound (phloroglucinol) and tested at 1 – 3 % loading in epoxy resin DGEBA-IPDA. Results show that the PIN FRs significantly reduce pHRR (peak heat release rate), THR (total heat release) and EHC (effective heat of combustion).
The additive PIN FR version shows a plasticising effect on the epoxy resin (lowering of the glass transition temperature Tg) whereas the reactive FR version reduces the epoxy functionality of the resin but shows better fire protective char formation. Both versions show strong intumescent fire protection effects, by generating expanded, insulating residue on the polymer surface (char). The authors conclude that bio-based phenolic phosphorus sulphur PIN FRs offer significant potential for fire safety treatment of epoxy resins, with reactive versions showing most promise.
“Synthesis of biobased phosphorus-containing flame retardants for epoxy thermosets comparison of additive and reactive approaches”, Polymer Degradation and Stability 120, 2015 , R. Ménard et al. http://www.sciencedirect.com/science/article/pii/S014139101530046X
See also Ménard et al. I pinfa Newsletter n° 47