Effects of ultraviolet radiation on morphology and thermo-mechanical properties of shape memory polymer based syntactic foam

Recently, shape memory polymer (SMP) based close-celled syntactic foam has been developed as a lightweight self-healing composite or sealant in expansion joints. In this study, SMP based syntactic foam was prepared and programmed by 2-D stress condition (compression in one direction and tension in a transverse direction). To investigate the durability of the smart foam under environmental attacks, accelerated aging of up to 90 days exposure to ultraviolet (UV) radiation was conducted. Combined UV radiation and water immersion (rain water and saturated salt water) were also investigated. The effect of various environmental attacks on the morphological, mechanical, and functional properties of the foam was evaluated. It is found that, although the accelerated aging by UV or/and water leads to a decrease in strength, ductility and shape recovery functionality, the decrease is insignificant. The 2-D programmed foam after environmental attacks is still able to serve as an effective shape memory material.