THERMAL DECOMPOSITION OF PERFLUOROCYCLOBUTANE IN A SINGLE-PULSE SHOCK TUBE

The thermal decomposition of perfluorocyclobutane was studied between 1100 and 1265°K behind reflected shock waves in a modified single-pulse shock tube using dilute c-C4F8-Ar mixtures. Reflected shock temperatures were evaluated from the Rankine-Hugoniot equations using measured incident and reflected shock velocities Analyses were carried out by mass spectrometry and gas chromatography. The observed reaction product was almost exclusively C2F4 except at the highest temperatures where small amounts of C3F6 were also observed The principal process involves the unimolecular decomposition, c-C4F8 → 2C2F4. The first-order high-pressure rate constant was found to be k∞ = 1016.0±0.6 exp[(-75,500 ± 3000)/RT]sec-1 in good agreement with previous low temperature data obtained in a static system.