Here, an experimental study is carried out to understand the degradation of crosslinked polymeric materials by exposure to coupled thermo- and photo-oxidation, and their eects on mechanical behavior of the material. Our investigation specifically focuses on two cured elastomeric adhesives: (i) a silicon-based and (ii) a polyurethane-based adhesive. Samples were prepared and subjected to UV radiation at three dierent temperatures namely 45, 60 and 80C, for dierent aging periods ranging from 1 to 150 days. Chemical damage is characterized by the FTIR, DSC and Swelling tests which help us to monitor the change in the chemical composition of the materials along the aging durations and conditions. Mechanical damage is characterized by uniaxial tensile failure test, cyclic tensile test and permanent set test. These tests revealed the change of behavior of our materials along the aging periods and conditions. The changes in mechanical behavior vary depending on the material, aging temperature and duration. We show that behavior of the materials aged in the photo-oxidative environment is in fact a result of a combination of two separable modes of damage, Mechanical and Environmental. Accordingly, We are able to further separate the environmental damage mode into one created by the eects of temperature and another created by the combination of temperature and radiation. This separability has been confirmed with a Neo-hookean model, which proved that for a combined state of aging such as photo-oxidation the material cannot be characterized by models which consider only single modes of damage. Such regimes would require approaches such as the micro-mechanical approach to fully consider the eects by all the damage modes found in complex aging phenomena.
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