:Calcium – zinc stabilizers .Metal soaps are a type of heat stabilizers for PVC that are composed of a mixture of at least two metals, with one metal responsible for color preservation in the initial processing stages and the other metal responsible for long-term heat stability, such as calcium-zinc (Zn) stabilizers, which have been widely used in PVC applications for over 25 years. These materials are generally based on metal carboxylates and sometimes incorporate other