Using materials

• Soda-lime glass

  Made of sand (silicon dioxide), sodium carbonate and limestone (calcium carbonate)
• Borosilicate glass


  Made of boron trioxide and sand
• Examples of clay ceramics

  brick

  china
• Clay ceramics are made by shaping wet clay at heated in a furnace
• Clay ceramics are often coated by glaze, which forms a hard, smooth, opaque and waterproof layer
• Low density poly(ethene)

  ->polymer chains are branched

  ->molecules are arranged randomly
• High density poly(ethene)

  polymer chains are less branched
• Thermosoftening plastics

  ->melt when heated

  ->can be recycled

  ->do not have covalent bonds between polymer molecules

  ->molecules can move over each other when heated
• Thermosetting plastics

  ->do not melt

  ->char and burn when heated

  ->electric plugs

  ->has cross links between polymer molecules (covalent bond)
• Composite material

  ->consists two or more materials with different properties

  ->reinforcement

  ->matrix

  ->combine to produce material with improved properties
• Reinforcement

  fibres that go through the matrix material
• Matrix

  substance that binds reinforcement together
• reinforced concrete

  reinforcement: steel

  matrix: concrete
• fibreglass

  reinforcement: glass fibres

  matrix: polymer resin
• carbon fibre reinforced polymer

  reinforcement: carbon fibres

  matrix: polymer resin
• chipboard

  reinforcement: wood chips

  matrix: resin glue

  ->contains randomly arranged wood chips so it is strong in all directions
• Fibres in composites have low density and are strong in tension —>not easily stretched but flexible
• wood

  reinforcement: cellulose

  matrix: lignin

  ->cellulose fibres are aligned alongside each other so wood is stronger on one side
• Concrete: compressive strength > tensile strength

  Steel: tensile strength > compressive strength

  Reinforced concrete: strong in tension and in compression, strong and slightly flexible
• Glass ceramics

  Appearance: transparent

  Melting point: high

  Brittle and stiff

  Ability to conduct heat and electricity? Poor

  Strength: relatively poor
• Clay ceramics

  Appearance: opaque

  Melting point: high

  Stiff and brittle

  Ability to conduct heat and electricity? poor

  Strength: stronger under compression
• Metals

  Appearance: shiny

  Melting point: high

  malleable

  Ability to conduct heat and electricity? good

  Strength: strong
• Plastics

  Appearance: various

  Melting point: usually lower

  Usually flexible

  Ability to conduct heat and electricity? poor

  Strength: relatively weak
• Composites

  Appearance: usually opaque

  Melting point: high

  Usually stiff and brittle

  Ability to conduct heat and electricity? poor

  Strength: usually very strong