PIN FRs enable high fire performance HFFR cables which retain structure and water resistance in fire.
The authors review research and patents into PIN FR ceramifiable polymer-based compounds, in silicone-rubbers (cross-linked), styrene-butadiene rubber, ethylene, polyvinyl acetate, ethylene vinyl acetate, ethylene propylene diene, epoxy and wood materials. Formation of a ceramified surface layer in fire results in fire protection of the polymer substrate by a self-supporting ceramic char layer which is resistant to fire-fighting water spraying, and also inhibits melt dripping. Ceramisation is optimised by a combination of silicate compounds, which form ceramic matrices (both as additives or from the polymer in silicone rubbers), ammonium polyphosphate and magnesium hydroxide which react to form crystalline phases in fire, fluxing agents and synergists to facilitate reactions.
“Polymer-based ceramifiable composites for flame retardant applications: A review”, Y-M. Li & S-L. Hu (Chongqing, China) and D-Y. Wang (IMDEA Materials Institute in Madrid), Composites Communications 21 (2020) 100405 https://doi.org/10.1016/j.coco.2020.100405