Plastics

Plastics

most are synthetic materials
1. man- made, using chemical processes
two types
1. thermo-plastics
  1. get soft when heated, allowing their shape to change- will harden in new shape
  2. flxible
  3. most, plastics- available in sheets (which can be heated and formed) (bathtubs are made from vacuum forming)and powders
    1. injection moulding
  4. hundreds of diff types
    1. acrylic
      1. rigid and clear with good impact resistance
    2. nylon
      1. clothes
      2. bearings
      3. gears
    3. polypropylene
      1. medical syringes
      2. rope
      3. crates
      4. storage boxes
2. thermo-sets
  1. once formed, cannot be changed using heat
  2. hard and rigid
  3. products that are heat-resitant and keep shape
    1. urea formaldehyde
      1. elec sockets
    2. melamine formaldehyde
      1. hard, rigid and strong- plastic bowls, laminated surfaces
    3. exoxy resin and polyester resin
      1. reinforced with glass fibre- canoes
      2. good chem resitance, but can be brittle
  4. are normally available as different chemicals to mix together
    1. cannot normally be recycled
most made form crude oil
1. drilling deep into ground/ sea
2. broken down into simple parts: monomers
  1. attached together to form polymers: the pure form of any plastic
3. non-renewable
4. pollution and damage to environment
5. plastics often end up buried in landfill- and they take 100s of years to break down- so this is a problem
6. but some are made form bio-degradable sustainable sources

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	Criado por fampulli mais de 10 anos atrás