A polymeric N-P-siloxane PIN FR with iron oxide achieved UL94-V1 (3 mm) at a combined loading of 2% in PET. Poly(N,N dimethylene phosphate aminopropyl siloxane) (PDPSI) was tested with F2O3 in PET, with five different combinations of total load 2% (from 0% to 2% PDPSI) and compared to neat PET. Optimal combination was 2/3 iron oxide to 1/3 PDPSI, which increased LOI by over 25% and re-duced peak heat release rate by 66% (compared to neat PET), achieved UL94-V1 no dripping and reduced total smoke production by 44%. Continuous and dense char was generated. The strength of the PET was reduced by <2%.
“Study on flame retardancy and smoke suppression of PET by the synergy between Fe2O3 and new phosphorus containing silicone flame retardant”, Y. Peng et al., High Performance Polymers, April 2020 https://doi.org/10.1177/0954008320914365