Enhancement of materials

• material enhancement is a way of improving a materials mechanical properties to better suit requirements of the final product

  • usually carried out on polymers, woods and metals
• polymer enhancement


  polymers are generally inert so will resist most chemicals and fungal attack

  • additives make polymers easier and less expensive to process - lubricants, thermal antioxidants and pigments are used
• polymer additives


  • improve product function
  • prolong life (prevent degradation)
  • encourage degradation
• additives to improve product function (polymer)


  • antistatic give the product great resistance to static - stops build up
  • flame retardants (bromine or metals) help reduce chance of the spread of fire
  • plasticisers allows the polymers to become less hard and brittle - used in food packing industry
  • fillers have a dial function - to bulk out product or improve polymer properties
• additives to prolong life - prevent degradation (polymers)


  • antioxidants help reduce environmental deterioration of the polymer of exposure to oxygen in the air
  • UV light stabilisers prevent the polymer chain being broken down by exposure to UV rays
• additives to encourage degradation (polymers)


  biodegradable plasticisers are similar to the ones used to enhance polymers

  • make the polymer more flexible, softer and easier to break down

  polymers break down in different conditions - bio-batch additives:

  • oxy-degradable polymers - degrade in the presence of oxygen
  • photodegradable polymers - degrade when exposed to UV light
  • hydro-degradable polymers - degrade in the presence of water
• wood enhancement


  natural wood can have defects such as knots or splits that can affect the overall stability of the wood - manufactures boards were developed to avoid this

  • strength decrease when wet
  • highly combustible
  • can rot and fungi and insects can attack
  • different properties in different directions
• wood additives


  • enhancement using preservatives
  • resins and laminations
• enhancement using preservatives (wood)


  • preservatives are used to prevent rot, fungal or insect attack and general weathering
  • wood can be treated to make it harder - the wood is impregnated with polysaccharide (similar to cellulose) which cures within the cell structure to increase toughness and stability
• resins and laminations (wood)


  • unusable parts of trees are enhanced - structural composite lumber (SCL) and laminated veneer lumber (LVL) are engineered to make strips of wood
  • this is used in natural woods to enhance beams, joists and rafters
• metal enhancement


  enhancement is not necessary for many metals as they have a wide range of properties already

  • work hardening - when a metal is 'cold worked' which causes the crystals in the metal to change causing improved tensile strength
  • can be removed by annealing
• metal additives 


  • annealing
  • case hardening
  • hardening and tempering
• annealing (metal)

  • makes work hardened metal easier to work by making it less brittle and more ductile
  • the metal is then slowly cooled - carried out in specific temperature controlled furnace
• case hardening


  process of hardening the surface of steels with less than 0.4% carbon - makes the surface more resistant to indention abrasion

  two stages:

  • carburising - changes chemical composition of the surface of low carbon steel so it can absorb more carbon
  • quenching - when the hot metal is quenched in water - fast cooling seals the hard surface without affecting inner core
• hardening and tempering (metal)


  hardening is the process of heating medium high carbon steel to alter the crystalline structure

  • holding for a long time at the temperature and then quenching causes extreme hardness but also brittleness

  tempering is a heat treatment for medium high carbon steels that is carried out after hardening to reduce excess hardness and increase toughness

  • reduction of hardness results in greater ductility and reduces the brittleness