polymerisation: this is the name of the process to describe how synthetic plastics are made.
- polymer chains are cross linking chains
- this is called covalent bonding.
- this stops them from being re-shaped.
- makes the polymer a very rigid structure.
- linked molecoles in long chains.
- held together by mutual attraction called 'van der waals' forces.
- this means when it is heated the bonds between the chains are weekened and become pliable.
- long chain coil like molecules
- when the material is distorted (compressed or stretched) the molecules distort & when released return to thier original state.
- the coils give elastomers their elastic properties.
Thermosetting plastics (can only be formed once)
- polyester resin
- epoxy resins
- urea formaldehyde (UF)
- melamine formaldehyde
Thermoplastics (can be reformed with heated several times)
- AMS (acrylonitrile butadiene styrene)
- cellulose acetate (CA)
- Acrylic (PMMA)
- polyproylene (pp)
- high impact polystyrene (HIPS)
- polystryrene (ps) rigid & expanded
- low density polyethylene (LDPE)
- high density polyethlene
- polyvinyl chloride (uPVC)
- polyvinyl chloride (PVC)
- polyethylene terephthalate (PET)