The Effects of Triphenylphosphine Oxide on the Thermal Decomposition and Combustion of Poly(Ethylene Terephthalate)

Abstract

A study was made of the effects of triphenylphosphine oxide on the thermal decomposition and combustion of poly-(ethylene terephthalate). Studies using differential thermal analysis and thermogravimetric analysis indicated that the decomposition of the polyester occurred by first order processes with an activation energy of 47.2 kcal/mole. The polyester was modified by the inclusion of triphenylphosphineoxide and nylon 6. These additives produced only minor changes in the energetics of the pyrolysis reaction. In all cases, the reaction was found to be predominantly pyrolytic since the kinetics were essentially independent of the nature of the atmosphere in which the thermolysis was carried out. The flame -retardant effects of the phosphine oxide nylon 6 system were characterized. Comparison of oxygen and nitrous oxide indices indicated that the effects were exerted predominantly in the vapor phase. The thermochemistry of the modified polyesters was studied with both oxygen bomb and isoperibol calorimetry. Heat evolution was abated by all the flame retardants investigated. In the ternary mixtures containing both phosphine oxide and nylon 6, the rate of heat evolution was decreased and resulted in enhanced flame retardancy