What is a shape memory alloy BBC Bitesize?
Shape-memory alloys (SMA) are metal alloys that can remember their shape when heated. These alloys have been utilised on spectacle frames that spring back to shape if they are squashed. Nickel titanium (nitinol ) is a type of SMA, and it contracts when heated, whereas most metals expand.
What property does a shape memory polymer have?
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape when induced by an external stimulus (trigger), such as temperature change.
What is a smart polymer GCSE?
Smart materials are materials that have properties which change reversibly, ie can change easily but can then easily change back, depending on changes in their surroundings.
Is polymorph a shape memory alloy?
Polymorph is a thermoplastic material that can be shaped and reshaped any number of times. Supplied as granules. Heated in hot water – at 62 degrees centigrade, the granules form a mass of ‘clear’ material that can be shaped into almost any form. On cooling it becomes as solid.
What are shape memory alloys used for?
Nickel-titanium (NiTi) shape-memory alloys (SMAs) have been used in the manufacture of orthodontic wires due to their shape memory properties, super-elasticity, high ductility, and resistance to corrosion. SMAs have greater strength and lower modulus of elasticity when compared with stainless steel alloys.
How do shape memory alloys change back to their original state?
Shape-memory materials behave differently. They’re strong, lightweight alloys (generally, mixtures of two or metals) with a very special property. They can be “programmed” to remember their original shape, so if you bend or squeeze them you can get that original shape back again just by heating them.
What are the benefits of shape memory polymers and shape changing polymers?
Because shape memory polymers can respond to temperature, light, pH and moisture, there are many very interesting possibilities for these materials in fabrics. These include comfort, aesthetics, wound monitoring, protection against environmental conditions, smart controlled drug release, and more.
Where are shape memory polymers used?
These polymers have been used to produce, among other things, medical devices such as stents and catheters. Typical examples of polymers which can exhibit this shape memory effect include (meth)acrylates, polyurethanes, and blends of polyurethane and polyvinylchloride.
Why is shape memory alloy A smart material?
Shape memory alloys (SMA) are materials that “remember” their original shape and can go back to this original shape after deformation under a stimulus. They are also known as smart alloys or memory metals.
What products use shape memory alloys?
KSM-SM alloy fields of application
| Shape-memory alloys | Superelastic alloys | |
|---|---|---|
| Personal accessories | Brassiere underwires, eyeglass frames, shoulder pad wires, petticoats, accessories | |
| Medical equipment | Dental implants | Orthodontic braces wire, Guide wires |
| Hobbies | Toys | Spinner lures, fishing through-wire |
Can polymers change shape?
A shape memory polymer can change from a temporary shape that is achieved by deforming it, to a previous shape which is its permanent shape when it is not being deformed.
How are shape memory polymers manufactured?
By conventional processing, e.g. extruding or injection molding, the polymer is formed into its initial, permanent shape B. Afterwards, in a process called programming, the polymer sample is deformed and fixed into the temporary shape A.
What are shape-memory polymers?
These so-called shape-memory polymers by far surpass well-known metallic shape-memory alloys in their shape-memory properties. As a consequence of the relatively easy manufacture and programming of shape-memory polymers, these materials represent a cheap and efficient alternative to well-established shape-memory alloys.
What is the effect of heat on shape memory polymer?
In shape-memory polymers, the consequences of an intended or accidental deformation caused by an external force can be ironed out by heating the material above a defined transition temperature. This effect can be achieved because of the given flexibility of the polymer chains.
What is an example of shape memory material?
For example, nitinol is a shape memory alloy of nickel and titanium. Hydrogels can absorb up to 1,000 times their own volume in water. After this water has been absorbed, it can be released when its surroundings are dry.
What is the difference between sunglasses and shape memory polymer glasses?
This means that these glasses act as sunglasses on sunny days, but quickly change back to normal glasses when the lenses are no longer in sunlight. Shape memory polymer is a polymer that can be bent out of its original shape and then returned to its original shape when heated.