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FURTHER QUESTIONS AND ANSWERS ON SMART MATERIALS

V. Ryan 2010

 

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1. Explain what is meant by the term ‘smart material’.

 
Smart materials can be regarded as materials that respond to a change of temperature, humidity, contact with water, electrical current or other inputs.
They usually change in terms of colour or shape when responding to an input.
 
2. Name a smart material and name / describe a product in which it is used.
 
SMART MATERIAL: Thermochromic inks are those that change colour in response to changes in temperature.
 
PRODUCT / DESCRIPTION: THERMOMETER. As the patient places the thermometer against his/her head, the thermochromic ink reacts to the change in temperature. A change in colour, against a temperature scale, indicates the patients temperature.
 
3. Explain why the smart material you named is used in the product.
 
The thermochromic ink is safe as it is non-toxic, unlike the traditional material of thermometers, mercury. It also reacts quickly to a change in temperature.
 
 
 
4. Describe / explain the following smart materials:
 
HYDROCHROMIC INKS:
These are inks that change when they make contact with water. A possible application of this type of ink is a gardeners moisture tester. If the tester is pushed into the soil near a plant, the colour of the ink will change indicating the moisture content. This allows the gardener to determine if the plant needs further watering.
 
POLYMORTH:
Polymorph is a thermoplastic material that can be shaped and reshaped any number of times. It can be heated in hot water and when it reaches 62 degrees centigrade, the granules form a mass of ‘clear’ material. When removed from the hot water it can be shaped into almost any form and on cooling it becomes as solid as a material such as nylon.
 
SHAPE MEMORY ALLOYS (SMA):
SMA wire is sometimes called ‘Nitinol’, as it is a composed of nickel and titanium. The material can also be ‘programmed’ to remember a shape by heating it to 150 degrees centigrade whilst clamping in the form of the required shape. If the wire becomes deformed later, if heated it returns to its original shape.
 
HYDROMORPHIC POLYMERS:
These are polymers that expand and contract on contact with water. This smart material is sometimes used in toys that can expand up to five times their original size, such as bath toys. An industrial application is that of seals for pipes. The seals expand if in contact with water, preventing leakage.
 
HYDROCARBON ENCAPSULATING POLYMERS:
These are polymers that absorb oil, forming a rubbery substance. This has a potential application for the prevention of oil slicks, at sea. They are environmentally ‘friendly’ products, developed to manage hydrocarbon-based liquid spills.
 
AROMA PIGMENTS:
These are inks that release an aroma when scratched or rubbed. The aroma is held within the pigment/ink as micro-capsules. The aroma pigments work many times before they loose their distinctive odour.
 
 
 
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