Teaching Modern & Smart Teaching Modern & Smart Materials in Design & Materials in Design &

TechnologyTechnology

A practical look at materials A practical look at materials presented by TEP at the DATA presented by TEP at the DATA

Millennium conferenceMillennium conference

Chris Rice

Director of Education

The National Curriculum The National Curriculum states …states …

2e: Pupils should be taught about the working characteristics and applications of a range of modern materials, including ‘smart’ materials.

Modern materials are those that are Modern materials are those that are continually being developed through the continually being developed through the invention of new or improved processesinvention of new or improved processes

TeflonTeflon Optical fibresOptical fibres NeopreneNeoprene Modified enzymesModified enzymes AntioxidantsAntioxidants Genetically modified foodsGenetically modified foods Synthetic flavoursSynthetic flavours Synthetic micro fibresSynthetic micro fibres Lycra blendsLycra blends PolartecPolartec Composite materialsComposite materials cellular materialscellular materials Carbon or Kevlar fibreCarbon or Kevlar fibre

Smart materials respond to Smart materials respond to differences in light or temperature. differences in light or temperature. They sense conditions in their They sense conditions in their environment and respond to them.environment and respond to them.

Shape memory alloysShape memory alloys Liquid crystals in coated fabricsLiquid crystals in coated fabrics Thermochromic dyes, (used to Thermochromic dyes, (used to

produce clothing that changes produce clothing that changes colour with light or temperature)colour with light or temperature)

Modified starchesModified starches

Modern MaterialsModern MaterialsPOLYMORPHPOLYMORPH (Polycapralactone) – This new polymer has a very low

melting point of 62`C. It can therefore be melted underwater. As a solid it has similar properties to an engineering nylon and can be used for a wide range of prototype work. It is an ideal vacuum mould material because of its ease of moulding and its ultimate mechanical strength. To reduce its mass you can build it up around other materials such as MDF, but it can be re-formed, making it cheaper in the long term than wasting large amounts of traditional materials

Modern MaterialsModern Materials

LENTICULAR SHEETLENTICULAR SHEET Improvements in production Technology have

made it possible to produce sophisticated optical effects in a wide range of plastic films and sheets. Plastic fresnel lenses, for example, are now common and inexpensive. Lenticular embossing has made it possible to print and animate many images on a single substrate.

Smart materialsSmart materials

SHAPE MEMORY ALLOY (SMA)SHAPE MEMORY ALLOY (SMA) A number of alloys exhibit useful memory characteristics.

A combination of Nickel and Titanium (NITAL) is one of the most common. It can be heat treated to remember that when its temperature is raised to 70`C it should contract by 5%. Cooling to room temperature it then relaxes to the original length. Applications range from coffee makers (replacing bi-metallic strip) to use in garments where body heat changes the characteristics of the fabric.

Smart ProductSmart Product

IQ CONTROLLERIQ CONTROLLER A self-contained unit capable of switching up

to three outputs on and off in a controlled sequence. The programmable chip is capable of both storing information and responding to environmental changes. IQ can be built into pupils projects to give ‘in-built’ intelligence or to simulate ‘smart’ performance in sophisticated prototypes

Smart materialsSmart materials

THERMOCHROMIC FILMTHERMOCHROMIC FILM This material has a self-adhesive plastic film,

which is then over printed with a thermochromic liquid crystal ink. As the temperature changes the crystals re-orientate and produce an overall colour change. This material is used to give temperature indications – e.g. baby thermometer patches or battery condition testers.

Applications of Modern & Smart Materials in the Applications of Modern & Smart Materials in the Design & Technology scheme of work at key Design & Technology scheme of work at key stage 3stage 3

•Units 9A (i) (ii) and (iii) Selecting materials

•Main aim is for pupils to apply their understanding of properties of materials.

• Food, Textiles and RM bias, with similar outcomes.

•Pupils have opportunity to learn about modern materials/ingredients, modified starches. Raise concerns re: biodiversity, GM crops, growth hormones and antibiotics. Blending polyester with cotton to reduce creasing (Marks & Spencer non-iron shirts). Micro fibres, thermochromic dyes, composites. Fabrics that change colour when exposed to extremes of heat or cold.

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Chris Rice Director of Education

Designing a Thermocolour

Display

This unit of work is intended to supplement or replace the Design & Make assignment contained within unit 9A(ii) (Selecting Material, Focus:Resistant Materials) of the National Scheme of Work at Key Stage 3 for Design & Technology

AIMThe main aim of this unit is for pupils to apply their understanding of a ‘Smart’ material (in this case, Thermochromicfilm) when designing. They should be able to identify a need for a product that could utilise this technology and go on to make their design.

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valuation

Liquid crystal is a very unusual material which responds to electrical signals. Many products such as calculators and laptop computers show information using liquid crystal displays (LCD). Thermochromic liquid crystal is a special form, which changes colour when heated. I t is put into minute capsules by a process called microencapsulation and then made into an ink for printing on to plastic or paper. Thermochromic ink has a number of uses including: Thermometers – which change colour along their length according to temperature change (Baby thermometers?) Warning patches – which show when something is overheating (Computer chip?) Battery test panels – The ink is printed on to a material that heats up when an electric current is passed through it. I f the battery is good the material will heat up the ink and cause it to change colour

“Organise a range of activities that give pupils the opportunity to learn about the diversity of a product.”

Explore the use of modern materials.

Carry out a Product Analysis.

PRODUCT EVALUATION

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Thermocolour fi lm consists of a thin fl exible plastic fi lm (called a substrate) which has an adhesive on one side and thermochromic ink on the other side. The fi lm is normally black but changes colour to bright blue at 27’C. Place your fi nger on the sheet and watch it change colour, unless your hands are below 27`C of course. I f the sheet is placed on to a metal base it will not work – why? Many electric fi res have an element of NI CHROME wire wound on a ceramic rod. Nichrome is an alloy of Chromium and Nickel. What is an alloy? I t has a high electrical resistance and gets hot when current passes, the smaller the diameter of wire and the longer its length, the higher its resistance.

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ask

Conducting some simple experiments Thermochromic fi lm only begins to change colour at a certain temperature. Pupils can experiment with diff erent heat sources to observe the eff ects. The fi lm changes colour at 27’C . I f the sheet is bonded to a good thermal conductor such as metal, it will not change colour. The fi lm should be bonded to plastic or f oam core board. When the source of heat is removed f rom the fi lm it stays warm f or a while then the blue colour changes slowly to pale yellow and back to black. Resistance wire Using a length resistance wire and a 3v power supply, pupils can arrange the wire on the sticky back of the fi lm. When the power supply heats up the wire, the fi lm will change colour along the pathway of the wire. The longer the wire is heated the more the blue area will spread out

Focussing on the knowledge, skills and understanding they will need during the DMA.

•Carry out test procedures on samples of materials

•Using the working characteristics of different materials

•Use their knowledge of the properties of materials

Focussed Practical Tasks

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A

Design and Make a Liquid Crystal Display based on thermocolour fi lm and resistance wire. The display is f or a purpose that you identif y – e.g. a badge, warning device, advertising display. The display should be controlled by a switch or a circuit. * PLEASE NOTE – When arranging your wire on the fi lm, wire should not be crossed or a short circuit will occur. I f the wire has to cross over in your design then use a small piece of paper as an insulator at the crossing. I deally the display should only be switched on f or a short time, so that the image does not spread out too much. Suitable control systems include: Momentary-action switches, which are on only as long as they are pressed Flashing control – Using a 555 timer Programmable display – Using a control device, bit by bit controller, kids chip, I Q controller.

Set the pupils a DMA in which they:

•Select materials according to their characteristics.

•Evaluate the materials chosen.

•Explore the uses of modern materials and use them sympathetically

Design and Make Assignment