4.10.3.3 - Ceramics, polymers and composites

What are ceramics?

Ceramics are non-metal solids with high melting points that aren’t made from carbon-based compounds  (e.g. glass and clay)

How are clay ceramics made?

Clay ceramics, including pottery and bricks, are made by shaping wet clay and then heating in a furnace.

Clay is ideal for pottery and bricks as it can be moulded when wet and then hardened

What type of glass is most of the glass we use?

Soda-lime glass

How and from what is soda-lime glass made from?

Made by heating a mixture of sand, sodium carbonate and limestone until it melts and when it cools it comes out as glass

Name another type of glass, other than soda-lime glass.

Borosilicate glass

How and from what is borosilicate glass made from?

Borosilicate glass is made from sand and boron trioxide (in the same way as soda-lime glass)

It melts at higher temperatures than soda-lime glass.

What do the properties of polymers depend on?

The properties of polymers depend on what monomers they are made from and the conditions under which they are made.

Name a polymer whose properties depend on it’s reaction conditions.

Poly(ethene)

Describe how the properties of poly(ethene) differ with different reaction conditions.

• Low density (LD) poly(ethene) is made from ethene at a moderate temperature and a high pressure - it’s flexible and used for bags and bottles

• High density (HD) poly(ethene) is made from ethene at a lower temperature and pressure with a catalyst - it’s more rigid and is used for water tanks and drainpipes

What does the monomers that a polymer is made from also determine?

The monomers that a polymer is made from also determine the type of bonds between the polymer chains - these weak bonds between the different molecule chains determine the properties of the polymer

What are thermo-softening polymers?

Thermosoftening polymers contain individual polymer chains entwined together with weak forces between the chains - you can melt these plastics and remould them

What are thermo-setting polymers?

Thermo-setting polymers contain monomers that can form cross links between the polymer chains - holding the chains together in a solid structure

Describe the main difference in properties between thermo-softening and thermo-setting polymers.

Thermo-setting polymers don’t soften when they’re heated as they are strong, hard and rigid - unlike thermo-softening polymers

Thermosoftening polymers melt when they’re heated, thermo-setting polymers don’t

What is a composite?

Composites are made of two materials - where one material is embedded in another

Fibres or fragments of a material (known as reinforcement) are surrounded by a matrix acting as a binder / a matrix or binder surrounding and binding together fibres or fragments of the other material, which is called the reinforcement.

What is the reinforcement in a comosite?

The fibres or fragments of material that is embedded in the other

What do the properties of the composites depend on?

The properties of a composite depend on the properties of the materials its made from

List some composites.

• Fibreglass

• Carbon fibre

• concrete

• wood

Describe the composition of fibreglass.

Fibreglass consists of fibres of glass embedded in a matrix made of polymer (plastic)

It has a low density (like plastic) but is very strong (like glass)

What is fibreglass used for?

Used for things like skis, boats and surfboards

Describe the composition of carbon fibre composites.

Carbon fibre composites also have a polymer matrix .

The reinforcement is either made from long chains of carbon atoms bonded together (carbon fibres) or from carbon nanotubes.

These composites are very strong and light

What are carbon fibre composites used for?

used in aerospace and sports car manufacturing

Describe the composition of concrete.

Concrete is made from aggregate (a mixture of sand and gravel) embedded in cement .

It’s very strong - making it ideal for use as a building material

Describe the composition of wood.

Wood is a natural composite of cellulose fibres held together by an organic polymer matrix.