C2 - Material Choices

C2 - Material Choices

1. Lesson 1: Properties of Materials

   • High Density
     • The material has a big mass for its size
   • Strong Under Tension
     • The material needs a big load to break it when stretched
   • Low Melting Point
     • The material will turn to a liquid at low temperature
   • Soft
     • The material can be scratched or dented easily
   • High Melting Point
     • The material will turn into a liquid at a high temperature
   • Strong Under Compression
     • The material needs a big load to break it when squashed
   • Low Density
     • The material has a small mass for its size
   • Flexible
     • The material will blend easily without breaking
   • Strong
     • Hard to break a material
   • Malleable
     • Can be easily reshaped under pressure
   • Weak
     • Easy to break a material
   • Brittle
     • Will shatter or fracture if pressure is applied
   • Stiff
     • This means that a material is difficult to bend or stretch
   • Hard
     • The material is difficult to dent or scratch

2. Lesson 2: Natural and Synthetic Materials

   • Natural
     • Not man made
     • Not chemically changed
     • Taken from earth or living thing
     • Materials from plants
       • Trees
         • Wood
         • Paper
       • Cotton Plant
         • Cotton
       • Rubber Trees
         • Rubber from tree sap
           • Car tyres
     • Materials from animals
       • Sheep
         • Wool
       • Silkworm
         • Silk
       • Cows
         • Leather
   • Synthetic
     • Man mdae
     • Chemically changed
     • Rubber
       • Factory
         • Wetsuits
         • Can control the properties
     • Clothes
       • Nylon
       • Polyester
       • Controlled by the manufacturer
         • Water proof
         • Super stretchy
         • Sparkly
     • Paints
       • Pigments designed to be tough
     • Raw materials
       • From Earth's crust
     • Metal alloys
       • Aluminium
       • Chromium

3. Lesson 3: Materials, Properties and Uses

   • Every material has a set of properties that make it perfect for some jobs and useless for others
   • Plastics
     • Hard
     • Strong
     • Stiff
     • Some are low density
     • Some are mouldable
     • Cases for televisions
     • Computers
     • Kettles
   • Rubber
     • Strong
     • Flexible
     • Mouldable
     • Rubber car tyres
   • Nylon fibre
     • Soft
     • Flexible
     • Good tensile strength
     • Ropes
     • Clothing fabric
   • Suitability
     • Cooking utensils
       • High melting point
       • Non-toxic
     • Toy car
       • Non-toxic
       • Strong
       • Stiff
       • Low density
     • Clothing fabric
       • Good tensile strength
       • Flame resistant

4. Lesson 4: Crude Oil

   • Mixture of Hydrocarbons
   • Sticky, dark liquid
   • Formed over millions of years from the remains of plants and animals all compacted together
   • Pumped out of Earth's crust using underground wells
   • Uses
     • Can not be used straight out of the ground
     • Can only be used when seperated
       • Fractional distillation
         • Groups with different boiling points
           • Called Fractions
             • Hydrocarbons within have similar boiling properties
               • Similar lengths
                 • Similar chain lengths
                   • Uses depend on lengths
       • Refining
     • Petrochemical Industry
       • Fuels
       • Lubricants
       • Raw materials
         • Synthetic chemicals
     • Hydrocarbons
       • Most used to make fuels
       • Small amount used to make new compounds
         • Plastics
         • Medicines
         • Fertilisers
         • Food
         • Called chemical synthesis
       • Less useful ones are split apart
         • Ethene
           • Plastics

5. Lesson 5: Polymers

   • Types
     • Strong and rigid
       • Polyethene
       • Plastic milk bottles
     • Light and stretchable
       • Low-density polyethene
         • Low melting point
       • Plastic bags
       • Squeezy bottles
     • PVC
       • Polyvinyl Chloride
       • Strong
       • Durable
       • Can be made either rigid or stretchy
         • Rigid
           • Piping
           • Window frames
         • Stretchy
           • Synthetic leather
     • Polystyrene Foam
       • Packaging
       • Thermal insulator
         • Disposable coffee cups
     • Heat-resistant
       • Melamine resin
       • Polypropene
       • Plastic kettles
   • Some polymers have replaced natural materials for some uses
     • Synthetic fibres
       • Nylon
       • Polyester
       • Replace
         • Cotton
         • Wool
         • Silk
       • Disadvantages
         • They aren't breathable
         • Can be uncomfortable next to the skin
       • Advantages
         • Lighter
         • More durable
         • Water-resistant
         • Cheaper
     • Rigid PVC
       • Replace
         • Wood
           • Window frames
       • Advantages
         • Weather-resistant
         • Strong
         • Durable
         • Makes windows more secure
           • Frames don't need painting every few years like wooden frames do
       • Disadvantages
         • PVC frames don't look as good

6. Lesson 6: Polymerisation

   • Plastics are formed when lots of small molecules called monomers join together to make a very long molecule called a polymer
     • Carbon-based
     • Under high pressure many small molecules 'join hands' to form long chains called polymers
       • Polymerisation

7. Lesson 7: Structure and Properties of Polymers

   • A polymer's properties decide its use
     • Depends on how the molecules are arranged
       • If the polymer chains are packed close together, the material will have high density
       • If the polymer chains are spread out, the material will have a low density
     • Depends on how they're held together
       • Chains held together by weak forces are free to slide over each other
         • Stretched easily
         • Low melting points
       • Plastics with stronger bonds between the polymer chains have crosslinks that hold the chains firmly together
         • Crosslinks are chemical bonds between polymer chains
         • Higher melting points
         • Can't be easily stretched
     • The stronger the bonds or forces between the polymer chains, the more energy is needed to break them apart, and the higher the melting point
   • Polymers can be modified to give them different properties
     • Chemically modified
       • Increase their chain length
         • Polymers with short chains are easy to shape and have lower melting points
         • Longer chain polymers are stiffer and have higher melting points
       • Adding cross-linking agents
         • These agents chemically bond the chains together
           • Makes polymer stiffer, stronger and more heat resistant
       • Adding plasticisers
         • Makes it softer and easier to shape
         • Gets in between the polymer chains
           • Reduces force between them
       • Polymer made more crystalline
         • A crystalline polymer has straight chains with no branches so the chains can fit close together
         • They have a higher density, are stronger and have a higher melting point

8. Lesson 8: Nanotechnology

   • Really tiny particles, 1-100 nanometres across are called nanoparticles
     • Nanotechnology is the branch of technology dealing with the making and use of nanoparticles
       • Some of the structures that are dealt with in nanotechnology are only as big as some molecules
         • Need to understand how to deal with things on a very small scale
   • Most nanomaterials are made using nanotechnology, but some nanoscale materials occur naturally or are produced by accident
     • Seaspray
       • The sea produces nanoscale salt particles which are present in the atmosphere
     • Combustion
       • When fuels are burnt, nanoscale soot particles are produced
   • Nanoparticles can be added to materials to give them different properties
     • Nanoparticles are added to plastics in sports equipment
       • They make plastic much stronger and more durable and they don't add weight
       • Tennis rackets
       • Golf Clubs
       • Golf Balls
     • Silver nanoparticles are added to polymer fibres used to make surgical masks and wound dressings
       • This gives fibres antibacterial properties
         • Kill bacteria
       • Normal silver particles are much bigger, have smaller surface area to volume ration and can't kill bacteria
     • Nanoparticles are much smaller than larger particles of the same material
       • Larger surface area-to-volume ration
         • Gives them different properties
         • Useful
   • The effects of nanoparticles on health are not fully understood
     • New products are tested thoroughly to minimise the risks
       • Some people are worried that products containing nanoparticles have been made available before the effects on human health have been investigated properly
         • We don't know what the long-term impacts on health would be
           • As the long-term impacts aren't known, many people believe that the products containing nanoscale particles should be clearly labelled, so that consumers can choose whether or not to use them

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