The influence of α-zirconium phosphate on fire performance of EVA and PS composites

Composites of polystyrene (PS) and poly(ethylene-co-vinyl acetate) (EVA) with organically modified zirconium phosphate (OZrP) were prepared by melt blending. Their morphologies were assessed by X-ray diffraction and transmission electron microscopy, while the thermal stability and flammability properties were characterized by thermogravimetric analysis and cone calorimetry. Increasing the OZrP content was not conducive to the formation of a nanostructure in EVA and poor dispersion of zirconium phosphate layers in PS at the nanometer level was observed. Increased thermal stability at high temperature and a slight reduction in peak heat release rate were found when OZrP was added to PS, while in EVA, deteriorated thermal stability and flame retardancy were observed. Unlike montmorillonite, the partial replacement of intumescent flame retardants (IFR) by 2% OZrP imparted a negative effect on the flammability of the EVA/IFR (23%)/OZrP (2%) composite, increasing the peak heat release rate of EVA/IFR (25%). The PS/IFR (18%)/OZrP (2%) composite with poly(styrene-co-maleic anhydride) (SMA) as compatibilizer exhibited better flame retardancy than PS/SMA/IFR (20%), prolonging the combustion process and increasing the time to peak heat release rate significantly. Copyright (C) 2011 John Wiley & Sons, Ltd.