C2 MATERIAL CHOICES
- Created by: mhamaia21
- Created on: 24-01-15 17:11
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- C2 MATERIAL CHOICES
- 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.
- 3. Each fraction condenses to liquid and runs off when cooled below its boiling point.
- 2. Vapour passes into fractionating column at bottom and cools as it rises.
- 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.
- Molecules are held together by intermolecular forces.
- 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.
- Natural rubber has strong covalent bonds between atoms but weak intermolecular forces.
- 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.
- Increasing length, increases bonds between atoms of molecules, so more energy is required.
- 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
- Results in a less flexible, stronger harder and higher melting point material
- Sulfur atoms make cross links between molecule chains (vulcanisation) locking molecules into a regular arrangement.
- 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.
- Results in softer, flexible, lower melting point material.
- Oily liquid, whose small molecules sit between chains, setting them apart, weakening intermolecular forces.
- 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
- Chains of molecules are neatly arranges with no branches, metal compound acts as catalyst in high pressure, regular surface of solid allows regular shape.
- Chain length
- 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
- Crude Oil
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