Interactive Primary Bulletin 43      CfE - Materials Special

New draft Experiences and Outcomes within Materials - Properties & Uses 

Amazing materials       How can they be used in teaching?   
 Experiment               Memory metals

Draft Outcome

By investigation and research, I have explored properties of novel materials and can convey my understanding of the innovative commercial and industrial applications of these materials and their potential benefits to society.   SCN 325X

 Amazing materials

Ultraviolet Beads - These UV-sensitive beads contain a pigment that changes colour when exposed to ultraviolet radiation from the sun. These beads are not affected by light from light bulbs because they do not give out ultraviolet light. So the beads will remain white if you shield them from sunlight or keep them indoors. The moment they get any sunlight though they will change colour very quickly. The solar-active pigment keeps the beads from permanently changing colour and speeds up the time it takes for the beads to change back to their original white colour.

Before sunlight                       After sunlight

This gadget will measure the strength of the sun's UV rays, tell you how long you're safe for, and give you accurate temperature readings.How can they be used in teaching?

Ultraviolet light is needed by many animals including humans to help them make vitamin D and also so they use calcium properly in the body. Too much though can damage eyes and skin cells and may even cause skin cancer in some fair skinned people. Sunglasses and suntan creams can help protect the body form the harmful rays.

These beads can be used to show the presence and intensity of UV light.

Experiment

Test your sunglasses by placing them in the sunlight and covering a few of the UV beads with the lenses. If the beads remain white, then your sunglasses are blocking harmful ultraviolet rays.

Test the effectiveness of your sunscreen by coating a few of the beads with the cream and placing them in the sunlight. If they change colour what does this mean? The sunscreen manufacturers suggest that you should throw away year old cream. How could you test to see if they are right?

Memory Metals - Metals that remember to go back to their original shape.

Nowadays many spectacles are made from an amazing material that can be bent and squashed and still goes back to its original shape. It is called memoflex and contains the metal titanium.

There is another metal with similar bendy properties which can also return to its original shape however this time it depends on temperature. Shape memory metal is made from an alloy, such as nickel titanium, which can be easily bent out of shape when cold but when heat is applied it will ‘remember’ to return to its original shape. See Nitinol demonstration video on YouTube.

Experiment

Take a piece of straight memory metal and coil it up as in the picture shown. Wearing safety goggles put about 5cm3 of boiling water (it must be above 90°C) in a plastic container. Carefully drop in the coiled metal; it can sometimes spring out of the beaker, and it will immediately change back into the original straight piece.

 

               Coiled up at room temperature                   straightens out in boiling water

How is this helpful?

An Italian design company, Corpo Nove designs clothes incorporating this technology. They have woven shape memory metal fibres into shirts, which mean that just applying hot air with a hairdryer can smooth the creases out. Could this be the end of ironing? Let’s hope so!

Shape memory metal can be used in many different ways, from clothing to aircraft. What applications can your class think of?

Materials - CSI primary - Forensic Science 

 
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