Ceramics, polymers and composites

Glass properties

• transparent

• Moulded when it is hot

• Brittle when thin

soda lime glass

• made by heating a mixture of sand, sodium carbonate and limestone

• This mixture melts and when the mixture cools it comes out as glass

borosilicate glass

Made from sand and boron trioxide

Higher melting point than soda lime glass

ceramic

non metallic solid with a high melting point that isn’t made from carbon based compounds

Clay

soft material when it is dug up out of the ground. Can be molded into different shapes. When fired at high temperatures by heating in a furnace, hardens to form a clay ceramic

Ideal for making pottery and bricks

low density polythene

made by heating ethene to 200 degrees under high pressure

Flexible, used for bags and bottles

high density polythene

Made at a lower temperature and pressure with a catalyst

More rigid, used for water tanks and drain pipes

Thermosoftening polymer

made up of individual tangled chains of polymers. Weak forces between the chains which means that these polymers are flexible and they can be melted and then remolded

Thermosetting polymer

have cross links which are covalent/ionic bonds between the polymer chains. This means that the polymer doesn’t melt when heated. When the polymer reaches a certain temperature, it just chars instead. Strong, hard and rigid

Metals

malleable and ductile

Good conductors of head and electricity

Shiny and strong

High melting and boiling points

composites

made up of 1 material embedded in another

Reinforcement

fibres/fragments of a material either in the middle of the composite of inside the other material

matrix/binder

what surrounds/binds together the reinforcement

Examples of composites

• wood

• Fibreglass

Wood

composite of cellulose fibres (reinforcement) held together by an organic polymer (matrix).

Gives trees strength, also a good building material as it is strong and has an attractive appearance

fibreglass

consists of fibres of glass embedded in a matrix made of a polymer/plastic

Low density, like plastic but is very strong like glass

Used for things like skis, boats and surfboards

Carbon fibre composites

carbon fibres for example are extremely strong and low weight so used they are used in aviation, aeronautics and for making professional racing bicycles

• Steel reinforced concrete has immense tensile and compressive strength allowing it to be used as columns and supporting structures in construction