C2

C2

1. NATURAL/SYNTHETIC

   • Natural materials are materials made from plants(wood, paper, cotton) or from animals(wool, leather, silk)
   • Synthetic materials are man made materials, such as rubber, nylon and polyester.

2. MATERIALS AND THEIR PROPERTIES

   • Strength: how good a material is at resisting a force.
     • Stiffness: a stiff material is good at not bending when a force is applied.
       • Hardness: how difficult is it to cut into.
         • Density: is a material's mass per unit volume(g/cm3)
   • Different materials have different properties. E.g, plastic is hard, strong and stiff, but rubber is strong but soft and flexible.

3. CRUDE OIL AND ITS USES

   • Crude oil is a mixture of hydrocarbons.
   • As the length of the carbon chain changes, the properties of the hydrocarbon change.
     • Short chain molecules have lower boiling points - they're often gases.
     • Long chain molecules have high boiling points and can be thick and sticky.
   • When seperated(by fractional distillation), crude oil is used in things such as petrol, kerosene and diesel.

4. POLYMERISATION/POLYMERS

   • Plastics are formed when lots of small molecules called monomers form together to make polymers. They are usually carbon based.
   • Polymers are used as alternatives to traditional materials such as: synthetic fibres(cotton, wool) rigid PVC(wood)
   • If the polymer chains are close together, the material will have high density. If they are spread out, it will have low density.
   • You can modify polymers by increasing the chain length. Longer chain molecules are stiffer and have higher melting points.
     • They can be made stronger by adding cross linking agents. This makes the polymer stiffer, stronger and heat resistant.
     • Plasticisers are added to make a polymer softer and easier to shape.
     • The polymer can be made more crystalline. These have higher density, are stronger and have a higher melting point.

5. NANOTECHNOLOGY

   • Nanotechnology is the branch of technology dealing with the making and use of these nanoparticles.
   • Nanoparticles are added to plastics in sports equipment. They make the plastic much stronger and more durable.
     • Silver nanoparticles are added to polymer fibres used to make surgical masks. This gives the fibre antibacterial properties.
   • The effects on human health have not been tested fully yet, so some people are worried about the long term effects they could have.