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PVC Stabilizer Guide

PVC Stabilizer Guide

PVC (Polyvinyl Chloride) is a very popular plastic that is used in many industries, including the building and construction sector, automotive, healthcare and leisure. It has a very good resistance to chemicals, oils and greases, but it needs to be stabilized against the action of heat when it is processed.

PVC resin has good electrical insulating properties, resistance to chemical corrosion, excellent mechanical strength and hardness. However, PVC is thermally unstable and has a tendency to degrade at elevated temperatures during processing. Stabilizers are added to PVC to allow its processing and to improve its resistance especially in outdoor applications, weathering and heat ageing and have an important influence on the physical properties of PVC finished articles. Factors such as process technology involved, technical requirements of PVC end product, regulatory requirements and cost, influence the choice of the stabilizer used.

All stabilizer systems for PVC consist of two main components: a heat stabilizer (primary) and a lubricant (secondary). Other additives can also be added such as light stabilizers (UV absorbers), fillers or pigments.

The primary role of the heat stabilizer (lead or organotin) is to protect the PVC from thermal degradation during processing by reacting with free radicals generated during heating

The commercial importance of PVC and the wide range of end-uses of PVC products has led to the development of numerous stabilizers. Stabilizers are added to PVC to allow its processing and to improve its resistance especially in outdoor applications, weathering and heat ageing. The stabilizer has an important influence on the physical properties of PVC finished articles. Factors such as process technology involved, technical requirements of PVC end product, regulatory requirements and cost, influence the choice of the stabilizer used.

Calcium Zinc stabilizers (Ca/Zn)

The original PVC stabilizer. Inexpensive, good heat and light stability. However, it is not very effective for the stabilization of polymers containing a high percentage of plasticizers, especially at high temperatures. It also has limited compatibility with other additives.

Lead stabilizers (Pb)

Lead stabilizers are used in PVC applications that require a high degree of resistance to heat, weathering and heat aging (such as roofing membranes). They have good flexibility and lubrication properties. However, due to their toxicity, they are being phased out in many countries worldwide. Lead based stabilizers are usually used together with Tin stabilizers to provide a synergistic effect.

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