Flame retardant and mechanical properties of natural fibre–PP composites containing magnesium hydroxide

Flammability of polypropylene, sawdust/rice husk filled polypropylene composites and flame retarding effect of magnesium hydroxide for these composites was studied by horizontal burning rate and oxygen index tests. Effect of flame-retardants such as boric acid or zinc borate in combination with magnesium hydroxide was also studied. It was found that magnesium hydroxide can effectively reduce the flammability (almost 50%) of natural fibre filled polypropylene composites. No synergetic effect was observed when magnesium hydroxide was used in combination with boric acid and zinc borate. Marginal reduction in the mechanical properties of the composites was found with addition of flame-retardants.