Wood – plastic composites combine natural fibres (e.g. sawdust or other timber production by-products) with polymers. The authors indicate that applications include construction and automobile, with a tendency to prefer PIN flame retardants because of low smoke and reduced toxic gases in case of fire.
Here, recycled polyethylene – sawdust (wood flour) composite was prepared with different PIN FRs (APP ammonium polyphosphate, ATH aluminium trihydrate, melamine, zinc borate). Without flame retardants, the sawdust contributed to combustion, whereas with PIN FRs it acted as a char source, enhancing fire resistance. The PIN FRs used in combination with polyethylene graft polymers (GPE, GPW) enabled to achieve UL94-V0 (4 mm) whilst maintaining high mechanical performance.
“Flame Retarded Polyethylene/Wood Flour Composites With High Performances: Satisfying Both Sides With Intumescent Flame Retardants and Synergistic Compatibilizers, Respectively”, H. Hong, Polymer Composites, 2016 https://dx.doi.org/10.1002/pc.23970