Use of non-traditional fillers to reduce flammability of polyester resin composites

This work reports the use of non-traditional fillers as flame retardants in polyester resin composites. Studies have been carried out to evaluate the fire-retardant properties of non-traditional fillers viz. hydroxyapatite, zinc borate and fly ash in combination with traditional fire retardant filler antimony trioxide, in prepolymer polyester resin composite system. Polyester resin was synthesized using phthalic anhydride (PA), maleic anhydride (MAN) and propylene glycol (PG). Flammability properties studied using limiting oxygen index suggests that incorporation of non-traditional fillers in creases fire retardancy with considerable improvement in mechanical properties. However, the effectiveness of fillers as flame retardants depends on several factors including the type of fillers and incorporation level of the fillers. The use of antimony trioxide and fly ash increases the fire resistance behavior but there is decrease in mechanical properties and thermal stability. The results reveal that good improvement in fire resistance with considerable increase in mechanical properties and thermal stability was obtained with 30% zinc borate as filler.