Synergistic effect of montmorillonite and intumescent flame retardant on flame retardance enhancement of ABS

The synergistic effects of organic montmorillonite (OMMT) and intumescent flame retardant (IFR) based on the ammonium polyphosphate (APP) and pentaerythritol ( PER) on flame retardant enhancement of acrylonitrile-butadiene-styrene copolymer (ABS) were investigated by using the limiting oxygen index (LOI), the UL-94 (vertical flame) test, thermogravimetric analysis (TGA), x-ray diffractometry (XRD) and scanning electron microscopy (SEM). The LOI data and vertical flame tests show that OMMT has a synergistic flame retardant effect with IFR and the LOI value of ABS/OMMT/IFR (96/4/20) reaches 28.7%. The TGA data demonstrate that the incorporation of OMMT and IFR is very effective in enhancing the thermal stability of ABS/OMMT/IFR system at high temperature (T > 500 degrees C). The results of XRD show that the composite of ABS/OMMT is a kind of intercalated nano-composite and the gallery height of ABS/OMMT nanocomposite is 3.5 nm. The microstructures observed by SEM demonstrate that a suitable amount of OMMT with IFR can promote formation of compact intumescent charred layers in ABS blends.