Correlation of chemical and mechanical property changes during oxidative degradation of neoprene

The thermal degradation of a commercial, stabilized, unfilled neoprene (chl oroprene) rubber was investigated at temperatures up to 140 degrees C. The degradation of this material is dominated by oxidation rather than dehydroc hlorination. Important heterogeneous oxidation effects were observed at the various temperatures investigated using infrared micro-spectroscopy and mo dulus profiling. Intensive degradation-related spectral changes in the IR o ccurred in the conjugated carbonyl and hydroxyl regions. Quantitative analy sis revealed some differences in the development of the IR oxidation profil es, particularly towards the sample surface. These chemical degradation pro files were compared with modulus profiles (mechanical properties). It is co ncluded that the profile development is fundamentally described by a diffus ion-limited autoxidation mechanism. Oxygen consumption measurements showed that the oxidation rates display non-Arrhenius behavior (curvature) at low temperatures. The current results, when compared to those of a previously s tudied, clay-filled commercial neoprene formulation, indicate that the clay filler acts as an antioxidant, but only at low temperatures. (C) 2000 Else vier Science Ltd. All rights reserved.