Rugby School Thailand Design & Technology Senior School

L.13 Modern Materials

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Modern materials

A modern material is a material that has been engineered to have improved properties.

Polymorph

Polymorph is sometimes considered a smart material but it is a modern material that has thermoplastic properties and can become malleable enough to shape in temperatures as low as 75 degrees C; essentially it becomes soft enough to form in hot water.

However, once cooled, it becomes rigid and is quite hard like a thermosetting plastic allowing it to be cut, drilled or even turned on a lathe.

Fibre optics

Optical Fibre is extruded glass or plastic, slightly thicker than a human hair. It can function as a light pipe to transmit light between the two ends of the fibre. Optical fibres are widely used in fibre-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables. Fibres are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. Fibres are also used for illumination, and are wrapped in bundles so that they may be used to carry images, thus allowing viewing in confined spaces.

Liquid crystal displays (LCD's)

Liquid Crystal Displays have been around for years in a variety of applications such as calculators, mobile phones and laptop computer etc.

Liquid crystals are carbon based compounds which in their natural form allow light to pass through. If a small voltage is applied they then block the path which is what makes them appear on the screen. LCDs can be reflective or backlit. Calculators are reflective while modern TV, tablets etc. are backlit which is why they are often difficult to see in bright sunlight. OLED (Organic Light Emitting Diodes) are a newer development of LCD’s where each pixel is its own light source.

Carbon Fibre

This material is made up of fibres of Carbon woven into a cloth like material to make them useful. These fibres are then impregnated with resin which bonds them together and forms a very strong material. The resin impregnated fibres are forced into a mould for shaping and heated until cured. The whole process, like glass fibre, can take days. Its light weight coupled with high strength make it suitable for a variety of applications including motorcycle helmets. Formula 1 car bodies, military applications and sports equipment

*Also a composite

Glulam

Glulam is glued laminated wood and is the use of several pieces of timber that are glued together to create strong, composite components for use in buildings, bridges and other structures. It is stronger and more stable than using solid timber and allows defects such as knots and shakes to be almost eliminated.

Kevlar

*Also a composite

Kevlar is a mixture of aromatic and aramid (Nylon-like) molecules melted together and spun into fibres. This material has a very high strength and, weight for weight, is five times stronger than Steel but half the density of Fibreglass. It has high chemical resistance and high cut resistance as well as being flame resistant.

It has various uses:

body protection, armour and helmets.
sports equipment
sails for windsurfing
run flat tyres that will not damage the rim
gloves for use with glass and sheet metal.

Coated Metals

Coatings for protection and decoration can be applied to sheet metals. These include polymer coated mild steel and aluminium. The polymer (PET or PP) can be applied as a transparent material or a range of colours. They are of food quality so they don’t taint the food and are commonly used for the inside of tin cans. Nickel coated steels are used where a non corrosive surface is required. Nickel coated steels are also used for moulds for injection moulding as well as vehicle parts and brake pipes.

Metal Foams

Developments in metal have resulted in foamed metals. Aluminium can be foamed in much the same way as polymers like Polystyrene. It results in a lightweight material that can be sandwiched between solid sheets for reduced weight. This allows for greater impact resistance; the solid sheet absorbs the impact which is dispersed through the foam. They can also be used for filtration of gas and liquid where higher temperatures would cause damage to a polymer based foam filter.

Titanium

It may seem unusual to include Titanium in this section but it is only fairly recently that it has been possible to extract it economically from its ore. Titanium has a very high strength to weight ratio which makes it suitable for the aerospace and medical industries. It is also used in jewellery, sports equipment and even colours for paints. It is corrosion resistant and does not react with bodily fluids.

Precious Metal Clays (PMC)

Precious metals such as Gold and Silver are suspended in clay which evaporates in a kiln allowing the metals to fuse together at around 650 degrees. It can be moulded and sculpted as easily as plasticine and, when fired, shrinkage of around 10% occurs. However, it is very expensive costing much more than the precious metal it contains.

Micro Fibres

These are very fine polymer based fibres, usually made from Polyamide (Nylon) or Polyester, that have been designed to mimic microstructures found in nature. They are waterproof and lightweight and are used in the sports and leisure industries.

Phase Change Materials (PCM)

A phase change material is a substance with a high heat of fusion which, melting and solidifying at a certain temperature, is capable of storing and releasing large amounts of energy. Heat is absorbed or released when the material changes from solid to liquid and vice versa; thus, PCMs are classified as latent heat storage (LHS) units. Hand and bottle warmers are an example of a PCM.

Dichroic Glass

Dichroic means two colours and Dichroic Glass is a material developed by NASA to reduce glare on the visors of space helmets as well as coating for space vehicles. Light is both transmitted and reflected by the glass which is coated in layers of metal oxides and quartz crystals. The glass reflects different colour light which give the appearance of changing colour as you look at it from different angles.

Graphene

A recently discovered material which is a single carbon thick but 100 times stronger then hypothetical steel (steel cannot exist in a single atom thickness). Despite its strength, it is almost invisible and incredibly light. If you had a 1 metre sheet of Graphene it would be able to support a 4kg cat yet it would weigh less than a single whisker. It is not yet commercially available yet the possibilities are fascinating. A proposed space elevator could be supported by a single ribbon of Graphene several kilometres above the earth yet only a few centimetres has been produced to date.

Summary

Smart materials are modern materials.
To be ‘smart’ they need to exhibit a physical change in response to an external stimuli.
Smart pigments can be used with other materials such as polymers and fabrics in order to give them ‘smart’ properties.
Smart materials are becoming increasingly common in consumer items such as colour change kettles and thermometers, dental braces, mobile phones and batteries.
Modern materials are relatively new materials and, while they can be very useful, they are not necessarily ‘smart’.

Summary of smart material properties:

Revision notes

Smart materials are often referenced in the examination, as are modern materials. You should ensure you know the difference between them.
Polymorph is not actually a smart material, but it is sometimes accepted as a correct response. However, find a better example if you can.
Smart materials are those that exhibit a physical reaction in response to an external stimuli.
For each smart material, you should be able to name a specific example of where it is used and explain what properties make it suitable for that purpose.
You should be able to do the same with any modern material.

Prep 13

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