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  • Created by: mhamaia21
  • Created on: 24-01-15 17:11
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    • Crude Oil
      • Synthetic materials are made from materials extracted from Earth's crust, such as crude oil.
      • Natural materials such as cotton, silk and wool.
      • Thick black liquid made from hydrocarbons.
      • Separated by fractional distillation into fractions with similar boiling points.
      • 1. Crude oil is heated to evaporate all hydrocarbons.
        • 2. Vapour passes into fractionating column at bottom and cools as it rises.
          • 3. Each fraction condenses to liquid and runs off when cooled below its boiling point.
            • 4. Remaining gases leave tower and are used as gaseous fuels.
    • Boiling points
      • Molecules are held together by intermolecular forces.
        • Longer hydrocarbon molecules, stronger force is.
        • Stronger intermolecular forces need more energy to overcome thus higher boiling points for longer hydrocarbon fractions.
    • Polymerisation
      • Small hydrocarbon molecules (monomers) are joined to make long molecules (polymers).
    • Polyvinylchloride is rigid and resistant to UV, used in window frames
      • PTFE, slippery, high melting point, unreactive, used for frying pans.
    • Using polymerisation
      • Paper carrier bags are now made from polythene because it is stronger and waterproof.
      • Wooden window frames are now polychloroethene because it is unreactive and does not rot.
    • Molecular structure of materials
      • Natural rubber has strong covalent bonds between atoms but weak intermolecular forces.
        • Long polymer molecules can slide over one another so rubber is flexible and has a low melting point because little energy is needed to separate molecules.
      • Vulcanised rubber is tangles molecules with strong covalent bonds between atoms and cross links (covalent bonds) between molecules.
        • Vulcanised rubber is rigid and hard to stretch, molecules won't slide past, high melting point.
    • Modifications in Polymers
      • Chain length
        • Increasing length, increases bonds between atoms of molecules, so more energy is required.
          • Results in strong, high melting point material.
      • Cross linking
        • Sulfur atoms make cross links between molecule chains (vulcanisation) locking molecules into a regular arrangement.
          • Results in a less flexible, stronger harder and higher melting point material
            • Car tyres and conveyor belts
      • Plasticizers
        • Oily liquid, whose small molecules sit between chains, setting them apart, weakening intermolecular forces.
          • Results in softer, flexible, lower melting point material.
            • Children's toys or (uPVC) in window frames.
      • Crystallinity
        • Chains of molecules are neatly arranges with no branches, metal compound acts as catalyst in high pressure, regular surface of solid allows regular shape.
          • Results in stronger intermolecular forces, higher melting point, stronger and denser material
    • Nanotechnology
      • One millionth of a millimetre = a nanometre
      • Nanoscale particles can occur naturally, sea spray, accidental human activity, particulate carbon, deliberately...
      • Smaller particles have a larger surface area resulting in different properties.
      • The production, study and control of tiny particles on a nanoscale, (1-100 nanometres)
      • Uses
        • Silver nanoparticles have antibacterial properties, stopping socks from smelling.
        • Carbon nanotubes in sports equipment make them lighter and stronger.
        • Nano particles in sunscreen, to avoid it showing
      • Risks
        • Different effect on animals and the environment.
        • Some worried they could enter brain via bloodstream and be toxic when so small.
        • New technology which hasn't been thoroughly tested


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