Yong Chae Jung

Polyurethane‐Carbon Nanotube Nanocomposites Prepared by In‐Situ Polymerization with Electroactive Shape Memory

In‐situ polymerization was employed to achieve well‐dispersed carbon nanotube‐reinforced polyurethane composites. In‐situ polymerization showed predominant as primarily dispersal of carbon nanotubes in the matrix polymer according to scanning electron microscopy (SEM) observation and atomic force microscopy (AFM) images. Differential scanning calorimetry (DSC) results suggested that the addition of multi walled nanotubes (MWNTs) into polyurethane increased the rate of crystallization, this effect being more significant in polyurethane (PU)‐MWNT composite, which was prepared by an in‐situ polymerization process. The composites obtained by in‐situ polymerization showed enhanced mechanical properties as well as good electroactive shape memory. The original shape of the sample was almost recovered with bending mode when an electric field of 50 V was applied.

Development and application of conducting shape memory polyurethane actuators

This paper presents the development and application of conducting shape memory polyurethane (CSMPU) actuators. While conventional shape memory polyurethanes were activated by an external heat source, the conducting shape memory polyurethanes, introduced in 2004, are activated by electric power. CSMPU actuators were manufactured by adding carbon nano-tubes to conventional shape memory polyurethane. The main problem of the previous CSMPU was poor dispersion of carbon nano-tubes. In this paper, we tried to solve the dispersion problem, and after a lot of elaborate work CSMPU actuators with better electrical characteristics were fabricated with in situ polymerization. Then the actuation performance of the CSMPU actuators was also measured and assessed. Finally, the possibility of applications was examined through the installation of a CSMPU actuator in a micro air vehicle.

Electroactive Shape Memory Effect of Polyurethane Composites Filled with Carbon Nanotubes and Conducting Polymer

We report the electroactive shape memory composites obtained by shape memory polyurethane block copolymer (PU) and multi-walled carbon nanotubes (MWNTs), and polypyrrole (PPy). An addition of combined MWNTs and PPy contributed to an enhancement in conductivity of PU-MWNTs composites. PU containing 2.5% MWNTs showed better mechanical and thermal properties than other composites, but conductivity was not sufficient for showing the shape memory effect by applying electrical voltages. However, when the composite was lightly coated by PPy (2.5%), its conductivity was the highest than other composites. Such the conductivity of this composite was enough to show electroactive shape recovery by heating above transition temperature of 40–48°C due to melting of polycaprolactone soft segment domain. The good shape recovery of 90–96% could be obtained in the shape recovery test when an electric field of 25 V was applied.

Actuation of MAV control surface using conducting shape memory polymer actuator

The current MAVs used servomotors as actuators for the control surfaces, such as elevators and rudders. In this paper, the application possibility of conducting shape memory polymer to smart actuator has been assessed. Our final goal will be to replace the servomotor with a newly developed conducting shape memory polymer actuator. As the first step, a conducting shape memory polymer with high transition temperature and high conductivity was manufactured and its properties were measured. Second, conceptual designs of special actuating systems for control surface of micro aerial vehicle are presented. The conducting shape memory polymer was composed of shape memory polyurethane block copolymer and carbon nanotube or carbon black. Its basic thermo-mechanical and conducting properties are discussed for application as electro-active shape memory polymer actuator.

Actuation performance of conducting shape memory polyurethane actuators

This paper presents the actuation performance of a conducting shape memory polyurethane (CSMPU) actuator. We introduced a concept of shape memory polyurethane activated by electric power in 2004, while conventional shape memory polyurethanes are activated by external heat source. A conducting shape memory polyurethane actuator was manufactured by adding carbon nano-tube to conventional shape memory polyurethane. The main problem of the previous CSMPU was bad dispersion of carbon nano-tubes in polyurethane. In this paper, we have tried to find manufacturing method to solve the dispersion problem. With a lot of elaborative works, we have developed conducting shape memory polyurethane actuator with good electrical performance. The actuation performance of the developed conducting shape memory polyurethane actuator was measured and assessed.