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 drawn into filaments and used as textile fibres.

Question 2

Thermoplastics

Answer 2

• Lines of long chains of molecules with very few cross linkages
• Soften when heated so can be bent into different shapes
• Becomes stiff and solid when cooled
• Process can be repeated many times
• Held together by mutual attraction (Van der Waals forces)

Question 3

Thermoplastic examples

Answer 3

• PVC (polyvinyl chloride)
• Polystyrene (HIPs, expanded)
• Acrylic
• Teflon
• Polycarbonate
• H.D.P.E (bottle lids)
• L.D.P.E (squeezy bottle)
• ABS (car dash boards, good impact strength)
• Polypropylene (strong, vacuum cleaners)
• PET (bottles, single use)

Question 4

Thermosetting plastics

Answer 4

Solidifies irreversibly when heated, and cannot be reshaped by heating. Usually 3D networked polymers in which the is a high degree of cross linking between polymer chains. Cross-linking restricts motion of the chains and leads to a rigid material. Held together by covalent bonds.

Plugs and socket covers are made from thermoset as they won’t melt if there is a spark

Question 5

Thermoset examples

Answer 5

• Bakelite (brown, made before urea)
• Epoxy Resin
• Melamine Formaldehyde (compression not injection, no bump at the bottom)
• Urea Formaldehyde
• Polyester Resin
• PVA