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
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 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.
Examples of common polymers and their uses:
|Polymer name||Typical use||Properties|
|Poly(ethene) or polythene||Plastic bags||Strong and hard-wearing|
|PVC||Water pipes||Strong, hard-wearing, chemically unreactive|
|PVC||Outer layer of electric wires||Electrical insulator, hard-wearing|
|Nylon||Clothing||Can be made into fibres, strong and flexible|
|Lycra||Sports clothing||Can 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.
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.
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
- 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.
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
There's more to learn
Have a look at these other resources around the BBC and the web.