Photodegradation mechanisms and physico-chemical properties of EPON-IPD epoxy-based polymers

Shape memory polymers are increasingly being utilized in aviation and biomedical industries. However, full realization of their potential is limited due to the lack of mechanistic understanding of their environmental degradation. To address this issue, the chemical structure, thermo-mechanical, morphological, and optical properties of an epoxy-based shape memory polymer during UV-induced aging were studied using FTIR, DSC, nanoindentation and SEM techniques after exposure to UV radiation up to 600 h. The proposed mechanism involves competition between chain scission and crosslinking. SEM and DSC analysis confirmed that an increased UV exposure not only increases the number and dimension of microcracks on the surface but also increases the glass transition temperature (Tg) of epoxy-amine based polymer. Similarly, elastic modulus (E) and hardness (H) were increased by ~22 and 33%, respectively, after 600 h of UV radiation.