XPS STUDY OF AN INTUMESCENT COATING APPLICATION TO THE AMMONIUM POLYPHOSPHATE PENTAERYTHRITOL FIRE-RETARDANT SYSTEM

Fire retardancy of polymers may be due to the formation of a protectiv e surface coating, i.e. a swollen charred layer (intumescence). An int umescent coating resulting from thermal treatments of the association of ammonium polyphosphate (APP) and pentaerythritol (PER) is studied b y X-ray photoelectron spectroscopy. The O 1s, P 2p, C 1s and N 1s spec tra are discussed. In the formation of the intumescent material the pr esence is shown of nitrogen in pyrrole and pyridine type structures of aromatic phosphate esters. A degradation mechanism is suggested which involves a reaction with O2 via the formation of carbonyl and carboxy lic groups.