Manufacturing of a shape memory polymer composite actuator with embedded heater

A new architecture of shape memory polymer composite (SMPC) sandwich actuator was developed. High-performance carbon fibre reinforced (CFR) prepreg was used for the external skins, whereas the shape memory functionalities were given by embedding square tablets of epoxy foams in the centre of the actuator. The epoxy foams were obtained by a solid-state process without using a foaming agent. Thermal activation of the smart actuator was induced through a flexible heater embedded during the lamination sequence. Finally, thin layers of the same shape memory (SM) resin used for the foams were deposited at the interface with the constituents. A SMPC actuator in the form of a 2-ply laminate with an embedded heater and with shape memory polymer (SMP) interlayer was also manufactured for comparison. The actuators were manufactured by a single-step hot press moulding process. Optical observations were carried out to evaluate the soundness of the adopted lab-scale manufacturing procedure, whereas shape memory, constrainedrecovery and free recovery tests were performed to investigate the shape memory capabilities and the recovery loads of the novel smart device. Comparable actuation loads (1.5N on average) were found for the two SMPC actuators while shape fixity and shape recovery ratios higher than 81% and 99% respectively were measured for the sandwich actuator.