KINETICS OF POLYMER DEGRADATION INVOLVING THE SPLITTING OFF OF SMALL MOLECULES .7. THERMOOXIDATIVE DEHYDROCHLORINATION OF PVC

High-conversion kinetic runs of the thermooxidative dehydrochlorination of PVC have been treated employing a theory developed previously. Satisfactory agreement between theory and experiment has been achieved. The kinetic parameters obtained by the non-linear least-squares method show that the activation energy and the pre-exponential factor for random elimination of HCl from PVC are identical with those for an inert atmosphere. Oxygen catalyzes the initiation step of the zip reaction by interaction with degraded parts of the polymer chain; the process is very complex. The rate constant for the catalyzed initiation is proportional to the square root of the mole fraction of oxygen present in the dehydrochlorination atmosphere. Oxygen also affects the zip growth, the zip length decreasing with increasing oxygen pressure.