Multiscale Characterization of Water-, Oil- and UV-Conditioned Shape-Memory Polymer under Compression

摘要

Shape memory polymers (SMPs) are an emerging class of active polymers that may be used for reconfigurable structures on air vehicles. In this study, epoxy-based SMPs were conditioned separately in simulated service environments relevant to Air Force missions, namely, (1) exposure to UV radiation, (2) immersion in jet-oil, and (3) immersion in water. The mechanical properties and shape recovery abilities of the unconditioned and conditioned SMPs were examined using large-scale compressive tests and small-scale nano-indentation tests. Results show that all the conditioned SMPs exhibit a decrease in Tg as compared to the unconditioned one. Under compressive loading, the SMPs undergo significant plastic deformation prior to fracture, except the UV conditioned sample. Environmentally conditionings generally result in higher moduli and yield strength of the SMPs. Environmental conditionings, in particular the UV exposure and water immersion, also affect the shape recovery abilities of the SMPs if the recovery temperatures are set low.