Plastics

Question 1

Thermo plastics

Answer 1

Made up of lines of molecules with few cross linkages allowing them to soften when heated and be bent into a variety of shapes and forms. Become stiff and solid again when cold. This can be repeated many times. Suitable for injection moulding, blow moulding and vacuum forming

Question 2

Acrylic (Perspex)

Answer 2

Most common plastic in school workshop. Purchased usually in sheets and comes in range of colours. Can be transparent (clear) translucent (smoked) opaque (solid colour). Resistance to most acids and weather conditions. 10x more impact resistance than glass

Question 3

Acrylic uses

Answer 3

• light units
• illuminated signs
• watch and clock glasses
• simple lenses
• aircraft canopies and windows
• car rear light units
• skylights
• furniture
• baths

Question 4

Plastics memory

Answer 4

Each time a plastic is reheated it will attempt to turn back to its original flat shape unless it has been overheated or damaged.

Question 5

Polythene

Answer 5

Can be moulded into almost any for due to its excellent moulding qualities. Two types, high density which is rigid and hard and low density which is tough and flexible. Used for production of toys, bowls, bottles, tubes etc.

Question 6

PVC

Answer 6

Tough material can be purchased as hard or flexible. Can be welded or bonded with an adhesive. Used for water pipes, raincoats, long play records and coating on electrical wire

Question 7

Thermosetting plastics

Answer 7

Made up of lines of molecules and heavily cross linked. Creates a rigid molecular structure. They cannot be re shaped again.