Polymers

• Toughness is the ability to withstand a sudden impact
• Hardness is the ability of a material to withstand scratching, cutting and abrasion (wear)
• Polymers are produced industrially through a process known as polymerisation
• Synthetic polymers are made from hydrocarbons
• Composition of the polymers can be adjusted to create different properties for specific purposes
• Two types of polymers: thermosetting and thermoforming
• Thermosetting polymers cannot be recycled
• Thermosetting polymers form cross-links between chains
• (ER) Epoxy Resin

  • Good electrical insulator
  • hard
  • brittle unless reinforced
  • resists chemicals well

  USED FOR

  adhesives

  casting

  encapsulation (eg: laminating paper)
• (PF) Phenol-Formaldehyde

  • Hard
  • Strong
  • heat and chemical resistant
  • good electrical insulator
  • limited colours available

  USED FOR

  Bowling balls

  Saucepan Handles
• (MF) Melamine-Formaldehyde

  • Stiff
  • hard
  • strong
  • resists some chemicals and stains

  USED FOR

  Laminates for work surfaces

  Hawker Centre tableware

  Electrical insulation
• (PR) Polyester Resin

  • Brittle but becomes tough when laminated with glass fibre
  • good compressive and tensile strength
  • hard
  • UV resistant

  USED FOR

  GRP boats

  Car Body Panels
• (UF) Urea-Formaldehyde

  • Stiff
  • hard
  • strong
  • brittle
  • good electrical insulator

  USED FOR

  Adhesives (MDF)

  Electrical Fittings
• ER = Epoxy Resin
• PR = Polyester Resin
• MF = Melamine Formaldehyde
• PF = Phenol Formaldehyde
• UF = Urea Formaldehyde
• (7) = Acrylic
• (6) = High Impact Polystyrene HIPS
• (3) = Polyvinyl Chloride PVC
• (1) = Polyethylene Terephthalate PET
• (5) = Polypropylene PP
• (4) = Low Density Polyethylene LDPE
• Heating weakens the join and softens the polymer, which means it can be reshaped by heating. As the plastic cools, it hardens to a permanent shape
• Polypropylene - Fatigue and moisture resistance
• Polyethylene Terephthalate - High Tensile Strength, food safe
• High-Density Polythene - Excellent Chemical Resistance, Able to be Sterilised
• Polyvinyl Chloride - Can be rigid or flexible, Hard (resistant to scratching)
• Polyvinyl Chloride - think of vinyl record
• High Impact Polystyrene - Fusibility (easy to mould), Lightweight, resistance to moisture
• Low Density Polythene - used for toothpaste container, ketchup bottles
• PET used for food packaging, fibres for clothing and plastic waterbottles
• PP (most common plastic) used for chairs, toys and bottle caps
• HDPE used for buckets, tubing and washing up bowls
• PVC used for Water pipes, raincoats and window frames
• PPMA used for Signs, Aircraft canopies and baths
• HIPS used for yogurt pots, refrigerator and vacuum-formed packaging
• Combining polymers with other materials can reinforce them (make them stronger) by combining the properties of both materials
• usually, thermosetting polymers (typically epoxy) are used because they come in a liquid state and can impregnate and form around the second material