XPS study of an intumescent coating II. Application to the ammonium polyphosphaterpentaerythritolrethylenic terpolymer fire retardant system with and without synergistic agent

Fire retardancy of polymer may be due to the formation of protective surface coating, i.e. a swollen char layer intumescence.. The intumescent coatings resulting from thermal treatments of the association of ammonium polyphosphate APP.and pentaerythritol PER.with or without zeolite 4A used as synergistic agent.in a polyethylenic terpolymer LRAM3.5.are studied by X-ray photoelectron spectroscopy. The O1s, P2p, C1s and N1s spectra are discussed. The formation of pyridinic and pyrrolic nitrogen and quaternary nitrogen in polyaromatic groups in the intumescent structures is shown. The oxidised nitrogen nitro groups and pyridine N-oxide.are only observed up to 3508C and then are evolved as NOx species. It is then proposed that the pyridinic function, observed only in the case of the system with zeolite at all temperatures, participates in the improvement of the fire proofing properties of the materials. q1997 Elsevier Science B.V.