X-ray photoelectron spectroscopy investigation of fire retarded polymeric materials: application to the study of an intumescent system

This work reports the chemical changes of an intumescent flame retardant ethylene vinyl acetate (EVA)-based material during combustion. Ammonium polyphosphate and polyamide-6 have been used as the acid source and the carbonisation agent respectively in the additive system. The main characteristic steps of the combustion were first determined using a cone calorimeter. The process of combustion was decomposed into several steps: heating before ignition, ignition, protection by a charred layer, destruction of the protective character of the carbonaceous shield, formation of a stable residue. At each step, the samples were removed from the cone calorimeter and analysed using X-ray photoelectron spectroscopy (XPS). It gives evidence of the presence of nitrogen atoms bonded to carbon in the protective shield. The effect of water rinsing of the obtained charred residue was also investigated. (C) 2002 Elsevier Science Ltd. All rights reserved.