Additives anti-ageing

Additives which change chemical properties during processing and in the final plastic product include anti-ageing additives in the form of antioxidants, heat stabilizers, light stabilizers and flame retardants. 

Antioxidants are usually in the form of antioxidant packages, combining two or more antioxidants (one of these, in general, is the primary antioxidant while the other is the secondary antioxidant, and both are expected to work together synergistically). The primary antioxidant helps to prevent or to terminate oxidative reactions. The secondary antioxidant helps to neutralise reactive materials that can create new cycles of oxidation. Antioxidants are also regarded as anti-ageing additives [15]. 

Photo/light stabilisers are anti-ageing additives. It is commonly known that PVC plastic windows can develop yellowish-brownish spots with time, mainly caused by sunlight... 

There is a broad range of additives for thermoplastics. Some of the more important additives include plasticizers, lubricants, anti-aging additives, colorants, flame retardants, blowing agents, cross-linking agents, and UV protectants. Fillers are also considered additives but are covered in Chap. 1. 

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