Chemiluminescence apparatus and method for studying thermal oxidative stability of polymers

A chemiluminescence multi-sample apparatus and method are described for determining polymer stability by measuring the intensity of the light emitted during thermal oxidation. Depending on the nature of a material analyzed the experiments are performed either under O₂ atmosphere at a constant temperature or under N₂ atmosphere at a constant heating rate. In the former case applicable to polypropylene (PP) and acrylonitrile-butadiene-styrene copolymers (ABS), parameters such as induction time and oxidation rate can be evaluated. In the latter case applicable to nylon and polyethylene terephthalate (PET), the extent of oxidation in a certain temperature region can be evaluated by measuring the area under the intensity of light—temperature curve. Along with providing a great deal of knowledge on thermal oxidative stability, the chemiluminescence approach gives the additional information concerning polymer quality. The appearance of the low-temperature pulses on the chemiluminescence curve observed before the onset of autocatalytic oxidation is associated with the history and processing of the sample and with the natural aging of the polymer.