The kinetics and mechanism of the thermal decomposition of azodicarbonamide in polyethylene. II. The effect of zinc oxide

ZnO acts on the thermal decomposition of azodicarbonamide (ADA, H2NCO=CONH2 ) by the inductive effect of its free O2- ions, by promoting the complexati on of the non-polar ADA and ZnO to a complex. The electrostatic force of th e O2- ions decreases the energy of activation of the formation (the cohesiv e force acting between the ADA molecules) of the ZnO-ADA complex. Knowing t his activation energy. a distance of 3.6 x 10(-8) cm could be calculated fo r the ligand, which is just the range of the length of hydrogen bonding. Ev idence for the formation of this complex was given by the change in the wav e numbers and absorbances of the infrared bands of zinc oxide, observed dur ing the decomposition. The time dependence of this change in the infrared a bsorbances could be simulated satisfactorily by using rate equations derive d on the basis of the mechanism proposed for the formation and decompositio n of the azodicarbonamide-zinc oxide complex. The rapid decomposition of th is complex increases the rare of thermal decomposition.