Thermal oxidation of hydroxyl-terminated polybutadiene rubber II. Oxidation depth profiles studied by imaging chemiluminescence

The chemiluminescence (CL) intensity during isothermal oxidation in the surface-layer and in the core from hydroxyl-terminated polybutadiene rubber was measured by an imaging CL instrument. Skin-core oxidation was observed and further indicated by infrared spectroscopy in terms of a carbonyl index and in the relative absorption of unsaturation. The oxidation depth in pre-aged samples, in terms of CL depth profiles, was evaluated from imaging chemiluminescence measurements in nitrogen atmosphere. The oxidation depth in pre-aged samples was in agreement with the depth of the CL emission during in situ oxidation. Samples subjected to a sinusoidal dynamic-mechanical compression during the oxidation indicated a prolonged oxidation in the surface layer. (C) 1999 Elsevier Science Ltd. All rights reserved.