Ceramics, polymers and composites

What are ceramics?

Non-metallic, inorganic solids made by heating substances to high temperatures.

What are the properties of ceramics?

✅ Hard and brittle
✅ High melting points
✅ Good insulators of heat and electricity
✅ Resistant to corrosion

Why is clay useful for making pottery and bricks?

✅ It is soft when wet, so it can be shaped.
✅ It hardens when fired at high temperatures.
✅ It is strong and durable when set.

What is glass?

A transparent ceramic made by melting sand (silicon dioxide) and cooling it rapidly.

What are the properties of glass?

✅ Transparent
✅ Hard but brittle
✅ Resistant to chemicals

What are the two main types of glass their composition, properties and uses?

Type of Glass	Composition	Properties	Uses
Soda-lime glass	Sand, limestone, sodium carbonate	Cheaper, easy to shape, brittle	Windows, bottles
Borosilicate glass	Sand, boron trioxide	Higher melting point, resistant to heat	Lab glassware, ovenware

What determines the properties of a polymer?

• Type of monomers used.

• conditions under which they were made

What are thermosoftening polymers?

Polymers with weak intermolecular forces between individual tangled chains, no crosslinks, allowing them to melt and reshape when heated.

What are their properties ( thermosoftening)?

✅ Softens when heated.
✅ Easily moulded into new shapes.

What are some uses of thermosoftening polymers?

✅ Plastic bags
✅ Water bottles

What are thermosetting polymers?

Polymers with strong cross-links between chains, making them rigid and heat-resistant with a high melting point as a lot of energy is needed to overcome these crosslinks

What are their properties ( thermosetting)?

✅ Does not melt when heated.
✅ Hard and durable.

What are some uses of thermosetting polymers?

✅ Electrical sockets
✅ Cooking pan handles

What is a composite?

A material made by combining two or more materials to improve properties.

How do composites work?

They have:

• Reinforcement (strong material like fibres or fragments).

• Matrix (binder) that holds the reinforcement together.

recall some examples of composites with their properties and uses

Composite	Properties	Uses

Fibreglass

Strong, lightweight, waterproof

Boats, helmets

Carbon fibre

Stronger and lighter than metal

Aerospace, sports cars

Concrete

Hard, strong under compression

Buildings, bridges

Wood (natural composite)

Strong, flexible, natural

Furniture, construction

How is LDPE made ( low density polyethene) and its uses and properties

• moderate temperatures

• high pressure

• catalyst

• properties - flexiible, weaker

• uses - carrier bags

How is HDPE made ( high density polyethene) and its uses and properties

• low temperature

• low pressure

• catalyst

• properties - rigid, stronger

• uses - drainpipes

explain why HDPE has a higher density than LDPE

because in HDPE polymer chains are closer together so more atoms per unit of volume