Which polymers are shape memory?
There are many different types of shape memory polymer and more are being developed all the time. Three commonly used engineering polymers that can demonstrate the shape memory effect (SME) include polytetrafluoroethylene (PFTE), polylactide (PLA), and ethylene-vinyl acetate (EVA).
How does the shape of the polymer affects the shape polymer?
Polymers exhibiting a shape-memory effect have both a visible, current (temporary) form and a stored (permanent) form. The polymer maintains this temporary shape until the shape change into the permanent form is activated by a predetermined external stimulus.
What is the difference between a shape memory alloys and polymers?
Differences Between Shape Memory Polymers and Alloys Elongation in alloys (up to 8%) is much less when compared to that of polymers. However, SMAs has some advantages such as their ability to reverse completely to their original pre- determined shape and also their better mechanical properties (Jackson et al., 1972).
What are the properties of shape memory alloys?
Shape memory alloys are a unique class of alloys that have ability to ‘remember’ their shape and are able to return to that shape even after being bent. At a low temperature, a SMA can be seemingly plastically deformed, but this ‘plastic’ strain can be recovered by increasing the temperature.
What are the properties of shape memory polymers?
Properties of shape-memory polymers. SMPs can retain two or sometimes three shapes, and the transition between those is induced by temperature. In addition to temperature change, the shape change of SMPs can also be triggered by an electric or magnetic field, light or solution.
What is the triple shape effect of polymers?
The triple-shape effect is a general concept that requires the application of a two-step programming process to suitable polymers and can be realized for various polymer networks whose molecular structure allows formation of at least two separated domains providing pronounced physical cross-links.
What kind of polymer can store three different shapes?
SMPs include thermoplastic and thermoset (covalently cross-linked) polymeric materials. SMPs are known to be able to store up to three different shapes in memory.
Can a polymer change from one shape to another shape?
Shape-memory polymers represent a promising class of materials that can move from one shape to another in response to a stimulus such as heat. Thus far, these systems are dual-shape materials. Here, we report a triple-shape polymer able to change from a first shape (A) to a second shape (B) and from there to a third shape (C).