The Use of Accelerated Tests in the Evaluation of Antioxidants and Light Stabilizer

esting of plastics generally involves accelerated methods whose greatest merit is their ability to yield experimental data rapidly. The results may in some cases be of no help in determining the useful life-time of the plastics end-product. This chapter critically examines the accelerated testing procedures used to assess the stability of plastics to thermo- oxidation and photo-oxidation.

Thermal analysis techniques such as DSC are discussed in detail. It is shown that although DTA/DSC is excellent for quality control purposes, it is of no value in the prediction of oven aging in the solid state. In the case of light stability, the results obtained in various accelerated exposure devices for multifilaments, tapes, films and injection molded plaques are compared with the corresponding data from out-door weathering, and the best correlation is found with exposure devices equipped with lamps that do not emit light of wavelengths below 295nm, e.g. filtered xenon arcs. However, even with such devices, correlation may be restricted for reasons related to the physical behavior of the light stabilizer system. This is demonstrated clearly for PP tapes.