EFFECT OF THE DISSOCIATION OF BARIUM AND CADMIUM STEARATES ON THE HEAT STABILIZATION OF PVC

Barium stearate (BaSt2), due to its greater dissociating ability, is a less effective heat stabilizer than Cd stearate (CdSt2) and exhibits considerably shorter induction times than CdSt2. Curves obtained by plotting induction time against the content of one of the components in the mixtures were asymmetrical, with a maximum in the CdSt2 range 60-65%, instead of 50%, which would be expected with stearates which have the same dissociating strengths. Kinetic calculations based on the different dissociating abilities of these stearates resulted in induction time curves having the same shapes as those measured.