Utilization of boron compounds as synergists with ammonium polyphosphate for flame retardant wood-polymer composites

The investigation consisted of utilizing boron compounds (BCs) as a synergist with ammonium polyphosphate (APP) in manufacturing flame retardant wood-polymer composites (WPCs). Flame retardants (FRs) at various ratios (APP, boric acid (BA), borax (BX), zinc borate and BA/BX mixtures) were used to determine the physical, mechanical, and burning rate properties of WPCs manufactured from wood flour, polypropylene, and maleic anhydride polypropylene. The results showed that the addition of FRs reduced all mechanical properties of WPCs except for impact strength. However, this reduction was lower for samples having BCs in FRs formulation. Similar burning rate results were achieved in WPCs having FRs. The combination of BA/BX with APP is thought to have overcome the negative effect of APP on strength properties through the formation of boron phosphate between APP and BA. BCs, used as the synergist, improved the mechanical and FRs performance of WPCs. This study showed that using BCs as synergists with APP has potential as a relatively inexpensive halogen-free FR alternative for the industry.