A review of shape memory alloy research, applications and opportunities

Shape-memory polymers (SMPs) have attracted significant attention from both industrial and academic researchers due to their useful and fascinating functionality. This review thoroughly examines progress in shape-memory polymers, including the very recent past, achieved by numerous groups around the world and our own research group. Considering all of the shape-memory polymers reviewed, we identify a classification scheme wherein nearly all SMPs may be associated with one of four classes in accordance with their shape fixing and recovering mechanisms and as dictated by macromolecular details. We discuss how the described shape-memory polymers show great potential for diverse applications, including in the medical arena, sensors, and actuators.

http://research.vuse.vanderbilt.edu/srdesign/2009/group8/Papers/shape%20memory%20polymers%20review%20article.pdf

Review of progress in shape-memory polymers

Shape-memory polymers

Shape-memory polymers and their composites: Stimulus methods and applications

Applied Numerical Analysis. By C.F. Gerald. Pp. xii, 340. £3·60. 1970. (Addison-Wesley.)

We demonstrate the new features of a polyurethane shape memory polymer: water-driven actuation and recovery in sequence (i.e., programmable). Hydrogen bonding is identified as the reason behind these features. In addition, the absorbed water is quantitatively separated into two parts, namely, the free water and bound water. Their individual contribution on the glass transition temperature is identified.

Water-driven programmable polyurethane shape memory polymer: Demonstration and mechanism

Effects of moisture on the thermomechanical properties of a polyurethane shape memory polymer

It was observed that the polyurethane shape memory polymer (SMP) loses its shape fixing capability after being exposed in the air at room temperature for several days. A significant indication for this change is the continuous decrease of the glass transition temperature (Tg) of polyurethane. Accompanying the decrease of Tg, the uniaxial tensile behaviour also changes. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests were carried out to find the cause behind this phenomenon. Moisture was concluded as the main reason. A mathematical expression was obtained for the relationship between Tg and the moisture. Moreover, the polyurethane shape memory polymer can fully regain its original properties after being heated at temperatures above 180 °C, which is the melting temperature of this SMP.

https://iopscience.iop.org/article/10.1088/0964-1726/13/1/022/pdf

Chuan Li

Papers

Water-driven programmable polyurethane shape memory polymer: Demonstration and mechanism

Effects of moisture on the thermomechanical properties of a polyurethane shape memory polymer

On the effects of moisture in a polyurethane shape memory polymer

Effects of moisture on the glass transition temperature of polyurethane shape memory polymer filled with nano-carbon powder

Electrical stimulation to promote osteogenesis using conductive polypyrrole films.