Stabilizers are a class of chemical additives commonly added to polymeric materials, such as plastics, to inhibit or retard their degradation. Polymers can be subject to various degradation processes, including oxidation, UV-damage, thermal degradation, ozonolysis, combinations thereof such as photo-oxidation, as well as reactions with catalyst residues or other impurities. These processes all degrade the polymer on a chemical level, leading to chain scission that can adversely affect its mechanical properties such as strength and malleability, as well as its appearance and colour.
Most carbon-based materials deteriorate over time due to the effects of light, atmospheric oxygen and other environmental factors. In plastics this can cause discoloration and embrittlement, which can reduce the useful lifespan of the object. Stabilizers are used to prevent this by inhibiting the various degradation processes such as oxidation, chain scission and uncontrolled recombinations and cross-linking. Typically, a number of different stabilizers will be needed in combination, each inhibiting a particular degradation pathway. The effectiveness of the stabilizers depends on solubility, distribution within the plastic, ability to stabilize, and rate of loss during processing and use. The effect on the viscosity on the plastic is also an important concern for processing.
