Abstract :
The thermal decomposition behavior of 1,4-diisobutyl-2,3,5,6-tetrahydroxy-1,4-diphosphorinane 1,4-dioxide (Cyagard), a fire retardant additive, was studied by thermogravimetry, differential scanning calorimetry, FT-IR and GC/MS. Cyagard decomposes vigorously exhibiting a strong sharp-exothermic effect. This effect is caused by a phosphine oxide → phosphinate → phosphonate rearrangement. The created POC ester bonds further degrade to form acidic POH and ketone PCOCH3 bonds. The scission of the PC bond yields acetaldehyde which evolves in the gas phase. In high boiling decomposition products, diphosphine dioxides, as well as species containing acidic POH and ester POC bonds are detected.
