Fused Filament Fabrication of Actuating Objects

Abstract

Thermoresponsive objects can be manufactured from shape memory polymers (SMPs) via fused filament fabrication (FFF). Here a new technological approach to obtain thermally actuating objects using an in-house synthesized, phase segregated poly(ester urethane) (PEU) is introduced. Under almost stress-free conditions of a dynamic mechanical analysis, cuboid objects obtained from FFF shrank when heated to 62 °C and expanded when cooled to 15 °C with a maximum thermoreversible strain of 7.2%. Actuation can be traced back to the phenomena of melting-induced contraction and crystallization-induced elongation of the PEU's soft segment, supported by internal stresses as implemented in course of FFF. To translate small changes in shape to a next larger scale, an artificial butterfly is developed in which the movements of two actuator elements are transferred to the wings with the aid of a lever concept. Following a different approach, additive manufacturing of cylindrical samples implied application potential as a self-sufficient gripper, enabling a programmable material behavior in the sense of temperature-controlled gripping, transport, and release of exemplarily selected smooth surfaced objects in the form of vials.