Biomedical Engineering Reference
In-Depth Information
distinguish higher temperature (hard segment) domain that acts as
a net point and the second one with
T
trans
temperature that acts as
molecular switch linked with chain segments in domains (switching
segments), as shown in Fig. 8.7.
Figure 8.7
Shape memory effect induced thermally, with characteristic
polymer architecture; switching molecule segments are related
to the thermal transition temperature
T
trans
[19].
Switching or transition in shape memory polymer can be
stimulated by heat or magnetism like in SMAs or MSMAs, and also by
light, water immersion, or even pH value. This gives a broad range of
possible applications that can be found in smart fabrics (for example,
in Fig. 8.8.), self-deployable sun sails for the spacecraft, intelligence
medical devices, or implants for minimally invasive surgery.
Figure 8.8
Degradable shape memory suture for wound closure, animal
experiment shows the shrinkage of iber with temperature
increase from left to right [19].
For brief considerations, we will focus only on the mechanism
of the shape memory effect and on the example of the thermo-
mechanical cycle of thermo-responsive SMPs.
In typically three-dimensional stress-strain-temperature
diagrams, we can observe controlled programming procedure with
the recovery of the test specimen. It is also important to mention
