Plastics

Question 1

Plastic

Answer 1

Any of various complex or organic compounds produced by polymerisation.

capable of being moulded, extruded, cast into various shapes and films, or dawn into filaments and used as textile fibres.

Question 2

Thermoplastics

Answer 2

• Made up of lines of long chains of molecules with very few cross linkages.
• Allows them to soften when heated so that they can be bent into different shapes.
• Becomes stiff and solid again when cooled.
• Process can be repeated many times.
• held together by mutual attraction, Van der Waals forces

Question 3

Thermoplastic examples

Answer 3

PVC
Polystyrene
Acrylic
Teflon
Polycarbonate
HDPE (bottle lids)
LDPE (squeeze bottle)
ABS (good impact strength)
Polypropylene (strong)
PET (single use bottles)

Question 4

Thermosetting plastic (thermoset)

Answer 4

• Solidifies irreversibly when heated.
• Cannot be reshaped by heating.
• Usually 3D networked polymer in which there is a high degree of cross linking between polymer chains.
• Cross linking restricts motion of the chains and leads to a rigid material.
• Covalent bonds

Question 5

Thermoset examples

Answer 5

Urea Formaldehyde
Epoxy resin
Melamine Formaldehyde (compression not injection)
Bakelite
Polyester resin
PVA

Question 6

Thermoset description

Answer 6

Set with heat and after has little plasticity.
During polymerisation molecules link side to side and end to end.
Covalent bonding gives a very stiff and rigid micro structure.
Once formed cannot be reheated.
Can’t be recycled