polymers

Cards (15)

  • Thermoforming- plastic becomes soft and flexible when heated
    • Join to form long polymer chains (no fixed structure or pattern)
  • thermoforming:
    Pros and cons: It can be repeatedly heated and moulded
    • Not suitable for hot areas or UV sensitivity
    • Each time plastic is reheated it it will try to return to its original shape (plastic memory)
    • Good surface finish can be achieved
    • Recycled easily (reused as it can reshaped)
  • Thermosetting- cannot be reformed once set to shape (melamine formaldehyde)
    • Chains of polymers resulting in a (cross linked) rigid molecular structure
  • thermosetting:
    Pros and cons: hard and durable with good structural rigidity
    • Can withstand high temperature
    • Good electrical insulator
    • Cannot be remoulded
    • Burns if reheated
    • Used to make composite materials
  • Vacuum forming- heat plastic until softened and draping into mould. Vacuum sucks plastic into mould then is ejected from the mould.
  • Blow moulding- blow into mould and set in shape.
  • Injection moulding- injecting softened plastic into mould (can make complicated shapes)
  • High Impact Polystyrene (HIPS)
    • flexible, lightweight, impact resistant, easily moldable, gloss finished 
    • Not very recyclable 
    • Example: expanded foam polystyrene (protect product packaging)
    • Suitable for food containers
    • (SELF FINISHING)
  • Acrylic (polymethyl-methacrylate)- Versatile and tough 
    • Scratches and easily and become brittle if thin
    • Acrylic fibres in clothing
    • Seen in sportswear, swimwear
    • Good insulator
    • Negative: not recyclable
  • Polyester resin- viscous, clear polyester solution
    • Hardened resin is tough and high abrasion resistance
    • Suitable for embedding objects (jewellery making)
    • Resin replicas (anatomical models)
  • Composite adhesive- polyester resin used in composite materials 
    • Lightweight and waterproof 
    • release agent is used for non stick purposes
    • Used to adhere layers fibreglass
    • Used in making boats, vehicle parts 
  • Urea formaldehyde (UF)- good electrical insulator
    • Paper industry: improve tear strength
    • Timber industry: UFresin to bind particles
    • Promote easy care and anti wrinkle properties in fabrics
  • Plastic properties- 
    • Self finishing 
    • Tough (impact resistant)
    • electrical, thermal insulator
  • Electrical insulator- prevent short circuit and ensure safety
    • Flexible PVC coating in UF
    • Thermoset plastics are used so they won't melt
  • Biodegradable polymers- made of plants
    • Plants are used for polymers instead of food (specially for LICs)
    • Thermoplastic
    • Suitable for takeaway box, non toxic, high melting point (able to injection mould)