Polymers, composites and ceramics

Home learning focus

Learn about polymers, ceramics and composites.

This lesson includes:

  • one video about different plastics
  • one video about reinforced concrete
  • two activities

Learn

Polymers

Polymers are long-chain molecules.

Polymers are some of most commonly used materials on Earth. This is because they exhibit certain properties that make them ideal materials for everyday use.

These properties include:

  • chemically unreactive
  • solids at room temperature
  • can be moulded into shape
  • electrical insulators
  • strong and hard-wearing

Plastics

Plastics are the most common example of a polymer material. They are mostly man-made and are created by combining carbon and hydrogen atoms together in long chains.

Watch this video where Mark Miodownik looks at where plastics come from, as well as some common uses for them.

Where do plastics come from?

Examples of common polymers and their uses:

Polymer nameTypical useProperties
Poly(ethene) or polythenePlastic bagsStrong and hard-wearing
PVCWater pipesStrong, hard-wearing, chemically unreactive
PVCOuter layer of electric wiresElectrical insulator, hard-wearing
NylonClothingCan be made into fibres, strong and flexible
LycraSports clothingCan be made into fibres, very elastic and tough

The disadvantage of plastics

Plastics have excellent properties that allow us to make use of them in different ways. Unfortunately, one property they have - chemically unreactive - means that they are extremely difficult to get rid of after use.

This leads to many different issues, including waste plastic causing danger to wildlife and damage to the environment.

Composites

Composite materials are made from two or more different types of material. For example, MDF is made from wood fibres and glue, and fibreglass is made from a mesh of glass fibres set in a tough polymer.

Steel-reinforced concrete is another composite material. It is made by pouring concrete around a mesh of steel cables. When the concrete sets, the material is:

  • strong when stretched (because of the steel)
  • strong when squashed (because of the concrete)

In this video, Mark Miodownik looks at how reinforced concrete is made and explains how this makes the material very strong.

How is reinforced concrete made?

Composite fabrics

Nylon is very waterproof. However, on its own it's not a good material as it keeps sweat droplets in.

Waterproof clothing is therefore a composite of different layers of fabric:

  • outer - waterproof layer of Nylon
  • middle - breathable material, eg. Gore-tex
  • inner - soft and elastic material

Ceramics

Ceramic materials:

  • are solids made by baking a starting material in a very hot oven or kiln
  • are hard and tough

The most common examples include: pottery, tiles, sinks, toilets and baths, and bricks.

Ceramic materials are used to make wall tiles, baths, sinks and toilets

Bricks

Bricks are ceramic materials made by baking moulded clay.

Advantages of bricks:

  • they are hard, so not easy to scratch
  • they are strong under compression, so a house will not be crushed under its own weight

Disadvantages of bricks:

  • they are brittle, so the bricks can break if handled carelessly during construction

Practise

Activity 1

Materials worksheet

Test your knowledge of different types of material with this downloadable worksheet from Beyond.

Materials worksheet

Activity 2

Materials scavenger hunt

Look for different materials around your home with this downloadable worksheet from Beyond.

Materials scavenger hunt

There's more to learn

Have a look at these other resources around the BBC and the web.

More lessons for Year 9 and S3
KS3 Chemistry
11-14 Chemistry
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