An infra-red spectroscopic study of the stabilization of poly(vinyl chloride) by zinc and calcium stearates

An i.r. spectroscopic investigation into the thermal stabilization of PVC by calcium and zinc metal soap systems has yielded new information on the role of these stabilizers. Complexation of the metal stearates occurs prior to gelation. Esterification of the polymer can also occur prior to gelation if “free” zinc stearate is present. After gelation, the stabilizing mixture acts primarily as an HCl acceptor irresective of the $\text{Ca}\text{Zn}$ ratio. The chemical and physical properties imparted to the matrix by the additives determine the rate of thermal degradation during processing in the Haake rheocorder.