C2 - Material Choices

C2 - Material Choices

1. Everything is made from atoms

   • Natural
     • Animals
       • Wool from sheep
       • Leather from cows
       • Silk from silkworms
     • Plants
       • Wood and paper from trees
       • Cotton
   • Synthetic
     • Rubber
       • A lot from trees
       • Made in factories can control porperties
         • use for different purposes
     • Clothes
       • Nylon
       • Polyester
       • Can control properties
     • Paints
       • Tough pigment to stop fading
     • Many raw materials from Earth's crust
       • Aluminium
       • Chromium

2. Materials and Properties

   • Melting Point
     • When solid turns to liquid
     • Higher means large molecule/ stringer forces
   • Strength
     • How good it is at resisting a force
     • Tensile Strenght
       • How much it can resist a pulling force
         • Ropes
     • Compressive Strength
       • How much it can resist a pushing force
         • Bricks
   • Stiffness
     • How good it is at not bending
   • Hardness
     • How difficult it is to cut into
       • Diamond
   • Density
     • Mass per unit volume

3. Uses depend on properties

   • Effectiveness
     • Depends on material made from
       • Alter over time to improve
     • Gramophones of paper, slate and wax
       • Records of PVC
         • CDs of polycarbonate
   • Suitability
     • Cooking utensils have high melting point
     • Clothes made from flexible material and good tensile strength
     • Toy car must be low density, non toxic, strong asn stiff
     • What jobs it works best for
   • Rubber
     • Mouldable
     • Strong
     • Flexible
     • Good for car tyres
   • Plastics
     • Mouldable
     • Hard, strong and stiff
     • TV/ Kettle/ Computer
     • Low density
   • Nylon fibres
     • Soft
     • Flexible
     • Good tensile strength
     • Clothing

4. Crude Oil

   • Mixture of hydrocarbons
     • Molecules made of carbon and hydrogen chains
   • Hydrocarbons
     • Larger = higher boiling point
       • More forces between molecules
         • More energy needed to separate them
         • Covalent bonds stronger
           • Don't break
     • Two types of bond
       • Intermolecular forces
         • Between different hydrocarbon molecules
       • Covalent bonds
         • Between hydrogen and carbon
         • Within the molecules
   • Uses of Crude Oi
     • Needs to be refined before useful
       • Fractional distillation
         • Hotter at bottom/ cooler at top
           • Larger separated at the bottom as higher boiling points
             • Smaller molecules refined as goes up
     • Fuels
     • Lubricants
     • New compounds
       • Plastics
       • Medicines
       • Less useful to make other compounds
         • Ethene
         • Chemical synthesis

5. Nanoparticles

   • 1-100 nanometers
   • Natural Nanoparticles
     • Sea spray
     • Soot from combustion
   • Man-Made Nanoparticles
     • Added to sports equipment
       • Stronger, durable, lightweight
         • Tennis racket
         • Golf ball
     • Silver Nanoparticles
       • Have antibacterial properties
         • Surgical masks and wound dressings
   • Effects
     • Not fully understood
     • Don't know long-term effects
     • People believe products containing should be clearly labelled as effects aren't known
   • 1X10-9 METERS

6. Polymerisation

   • Monomers join to make polymers
     • High pressure
   • Different monomers make different polymers
     • Strong and rigid
       • E.g. high-density polyethene for milk bottles
     • Light and stretchable
       • E.g. low density polyethene for plastic bags
     • PVC
       • Strong used for window frames
       • Stretchy used for synthetic leather
     • Polystyrene for packaging
       • Or disposable cups as good insulator
     • Heat resistant polymers
       • E.g. melamine resin or polypropelene
       • Plastic kettles
   • Some polymers have replaced natural materials
     • Nylon/ polyester replacing wool/ cotton in clothing
       • Ligher
       • More durable
       • Water-resistant
       • Cheaper
       • However aren't breathable so can be less comfortable
     • Rigid PVC replacing wood in window frames
       • Weather-resistant
       • Strong
       • Durable
       • No paint needed as often
       • Don't look as good as wood

7. Polymer structure can alter its properties

   • Density
     • Packed closer = higher density
     • Spread out = low density
   • Forces
     • Weak
       • Low BP/ MP
         • Less energy needed to separate
       • Polymers can slide over each other
         • Stretchable
     • Strong
       • High BP/MP
         • More energy needed to sepearate
       • Can't slide as forces restrict
         • Stiffer
   • Plasticisers
     • Reduce forces
       • Softer
         • Lowe MP/BP
   • Cross links
     • Bond chains together
       • Stronger
         • Stiffer
           • More heat resistant
   • Crystalline
     • Take out branches
       • Closer together
         • Denser
           • Higher MP/ BP
   • increase chain length
     • More forces
       • Stiffer
         • Higher MP/BP

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