Plastics

Plastics

1. most are synthetic materials

   • man- made, using chemical processes

2. two types

   • thermo-plastics
     • get soft when heated, allowing their shape to change- will harden in new shape
     • flxible
     • most, plastics- available in sheets (which can be heated and formed) (bathtubs are made from vacuum forming)and powders
       • injection moulding
     • hundreds of diff types
       • acrylic
         • rigid and clear with good impact resistance
       • nylon
         • clothes
         • bearings
         • gears
       • polypropylene
         • medical syringes
         • rope
         • crates
         • storage boxes
   • thermo-sets
     • once formed, cannot be changed using heat
     • hard and rigid
     • products that are heat-resitant and keep shape
       • urea formaldehyde
         • elec sockets
       • melamine formaldehyde
         • hard, rigid and strong- plastic bowls, laminated surfaces
       • exoxy resin and polyester resin
         • reinforced with glass fibre- canoes
         • good chem resitance, but can be brittle
     • are normally available as different chemicals to mix together
       • cannot normally be recycled

3. most made form crude oil

   • drilling deep into ground/ sea
   • broken down into simple parts: monomers
     • attached together to form polymers: the pure form of any plastic
   • non-renewable
   • pollution and damage to environment
   • plastics often end up buried in landfill- and they take 100s of years to break down- so this is a problem
   • but some are made form bio-degradable sustainable sources