A study of the flame‐retardant properties of polypropylene/Al(OH) 3 /Mg(OH) 2 composites

Abstract Polymeric materials are used extensively, but their applications are limited because many of them are flammable. Therefore ways to make them flame retardant have received much attention. In this work, polypropylene (PP) was used as the matrix resin, aluminium hydroxide (Al(OH) 3 ) and magnesium hydroxide (Mg(OH) 2 ) as flame‐retardant additives and zinc borate (ZB) as a flame‐retardant synergist. PP/Al(OH) 3 /Mg(OH) 2 and PP/Al(OH) 3 /Mg(OH) 2 /ZB flame‐retardant composites were prepared with a twin‐screw extruder. The flame‐retardant properties, i.e. oxygen index (OI), burning velocity and smoke density, of the composites were measured. The results showed that OI increased with an increase of the filler content and decreased with an increase of the filler particle diameter. The burning velocity decreased with an increase of the filler content, while it first increased and then decreased with an increase of the filler particle diameter. The smoke density decreased with an increase of the filler content and increased with an increase of the filler particle diameter. There was a flame‐retardant synergy between Al(OH) 3 /Mg(OH) 2 and ZB in the composites, and the smoke suppression effect was marked when ZB was added. Copyright © 2009 Society of Chemical Industry