PIN flame retardant high-solid phenolic foams were tested with 0 to 5% zinc oxide. The PIN FR foam contained 10% APP (ammonium polyphosphate, phosphorus – nitrogen FR) and 5% PER (penta erythritol, carbon source for char formation) and showed significantly improved fire performance (LOI – Limiting Oxygen Index, HRR – Heat Release Rate, THR – Total Heat Release, EHC – Effective Heat of Combustion) and also reduced toxic gas (carbon monoxide) production and yield (COP, COY) compared to non flame retarded foam.
Optimum zinc oxide load was c. 1%, resulting in reduced mean toxic gas release whilst not significantly deteriorating the foam physical properties (bending and compression strength).
“Effect of zinc oxide on properties of phenolic foams/halogen-free flame retardant system”, Journal of Applied Polymer Science, 2015, Y. Ma et al., http://onlinelibrary.wiley.com/doi/10.1002/app.42730/abstract