Lead Stabilizers Lead compounds were among the first materials to be used as stabilizers to prevent decomposition of PVC. Only Compounds derived from bivalent lead are relevant in practice with basic primary lead stabilizers and lead soaps being the most commonly used PVC stabilizers. Applications: Typical application for lead stabilizers include recyclable PVC profiles, pipes and cables with a long service life. Principle of action: Basic lead compounds are excellent HCI scavengers and are able to bind substantial amounts of hydrogen chloride during the decomposition of PVC. The resulting lead chloride is very stable, insoluble in water and does not encourage the decomposition of PVC. Stabilizer systems: Primary lead stabilizers are generally used in conjunction with lead soaps, calcium soaps, lubricants and antioxidants. Benefits: - Excellent long term heat stability. - Pigmenting effect of basic primary lead stabilizers are beneficial in light colored applications. - Low solubility in water, no leaking into the environment. - No odour during processing and in the final product. - No detrimental effects on the Vicat softening temperature of rigid PVC. Disadvantage: - Lead compounds in biologically available form are chronically toxic(as explained in the notes on precautions in handling lead products). - Discolouration in contact with sulphur staining)
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