Abstract :
2-Methyl-1,2-oxaphospholan-5-one 2-oxide (OP) is useful in a wide range of flame-retarded compositions. It is a thermally stable substance which, in inert atmosphere, looses weight at 200 °C on dynamic heating, leaving a solid residue, the amount of which is sensitive to the presence of moisture. Due to the reactive PO bond, the thermal stability of OP can be increased by reaction with amines or alcohols and it can be introduced into a variety of plastics. Upon pyrolysis at 450 °C, OP volatilizes and decomposes, producing CO2, low-chain hydrogencarbons, aliphatic and aliphatic–aromatic phosphine oxides and a black deposit, where polymeric phosphine oxides and phosphorus acid anhydrides were detected. Mechanism to explain the occurrence of the different products is proposed. Based on these data the condensed- and vapor-phase fire retardant mode of action of OP appear to be feasible.
