PVC Heat stabilizers can be classified by chemical composition into lead salts, metal soaps, organotin compounds, rare earth compounds, and organic auxiliary stabilizers. Their mechanisms of action include:

1. HCl Absorption: Lead salts (e.g., trisodium sulfate) neutralize HCl to delay catalytic degradation;

2. Allyl chloride displacement: Zinc soaps and cadmium soaps stabilize PVC molecular chains through esterification reactions;

3. Free radical scavenging: Organotin compounds (e.g., dibenzyltin maleate) terminate chain reactions via coordination reactions;

4. Conjugated double bond addition: β-diketones react with polyene structures to inhibit color deepening.