Epoxy-based shape memory composite for space applications

Shape memory polymers are smart materials with an ability to recover their permanent shape from a temporary shape upon exposure to various external stimuli. In space applications, shape memory polymers can find their use as deployable devices due to their high strength-to-weight ratio and large deformability. The effect of vacuum environment in space on the deployment of shape memory polymers is an extremely important issue which is yet to be studied. As the energy budget in spacecraft is limited, means to increase the energetic efficiency of deployable devices need to be developed. In this work, shape memory polymer actuators based on carbon resistive heating fibers and epoxy matrix were developed for space applications. Their mechanical, thermal, and electrical properties, as well as their deployment kinetics at both ambient and vacuum conditions, were studied. A method for improvement of the deployment energetic efficiency of shape memory polymer actuators, based on aluminum coating for internal radiative heating, was introduced. An innovative technique, which provides motion sensing at the first stage of the shape memory polymer actuators deployment, was demonstrated. This technique uses the resistive heating characteristics of carbon fibers and in situ electrical resistance drop during deployment. Finally, the durability of the shape memory polymers actuators in the space environment was discussed.