C2 - Material Choices

Natural and Synthetic materials
1. All materials are made of chemicals
  1. Made from atoms or groups of atoms (molecules)
2. natural
  1. Materials from plants
    1. Wood and paper from trees
    2. Cotton from cotton plant
  2. From anilmals
    1. Wool from sheep
    2. Silk from silkworm larvae
    3. Leather from cows
3. Synthetic - made by humans
  1. can control porperties
    1. Rubber altered in a factory
    2. Nylon and Polyester for clothes
      1. Waterproofing, stretchy, sparkly
    3. Paints
  2. Raw materials used to make synthetic materials come from the Earth's crust
Materials and Properties
1. Melting and boiling points
  1. The temperature at which a: solid turns to liquid or a liquid turns to gas
2. Strength
  1. The ability to resist a force before breakage or deformation
    1. Tensile
      1. Pulling force
        Ropes and cables
    2. Compressive
      1. Pushing force
        Concrete for construction
3. Stiffness
  1. Inflexibility
4. Hardness
  1. Difficulty to cut into a material
    1. Hard = Diamond
      1. Hardest naturally occuring material
    2. Soft = Paper
5. Density
  1. Materials mass per unit volume
    1. eg. g/cm3
  2. Buoyancy
    1. Objects which are less dense than water will float
    2. Objects which are more dense than water will sink.
Material's Properties and Uses
1. Uses for materials depend on the material's properties
  1. Examples
    1. Plastics
      1. Hard, Strong and Stiff
      2. Low density (lightweight)
      3. Mouldable
      4. Cases for TVs, Computers and Kettles
    2. Rubber
      1. Strong
      2. Mouldable
      3. Car Tyres
    3. Nylon Fibres
      1. Soft and Flexible
      2. Good tensile strength
      3. Ropes and Clothing
2. Properties of a product depend on the materials
3. Suitablity of material for use
  1. Cooking utensils
    1. Non toxix, high melting point
  2. Toy car
    1. non toxic, strong, stiff and low density
Nanotechology
1. Nanomaterials are tiny
  1. 1nm = 0.000 000 001m
  2. 1-100 nanometres across are nanoparticles
  3. Natural
    1. Sea-spray
    2. Combustion produces nano particulates
  4. Different properties than larger particles of the same chemical
    1. Sliver cant kill bacteria due to its lower surface area to volume ratio
2. Branch of technology dealing with nanoparticles
  1. Design nanomaterials for specific uses
    1. Strengthening sports materials such as tennis rackets, golf clubs and golf balls.
    2. Silver particles in surgical masks and plasters giving antibacterial properties
3. Ethics
  1. Effects of nanoparticles are unknown
    1. Testing is important
    2. Long term risks cannot be tested
      1. Clearly labled so that consumers can choose to use or not use
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C2 - Material Choices

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