Structural Integrity (plastics)

Question 1

Thermosetting polymers

Answer 1

They are naturally hard and brittle but can be made stronger and tougher by using other materials to reinforce them, for example a fibreglass boat hull.

Question 2

Glass reinforced plastic

Answer 2

The reinforcement of polyester resin using strands of glass fibre available as a woven mat or loose strands

Question 3

What does the glass fibre reinforcement give

Answer 3

• a much higher tensile and compressive strength
• a lighter, hard-wearing surface
• excellent resistance to corrosion

Question 4

How are thermopolymers moulded

Answer 4

As thin hollow shapes

Question 5

How is a hollow shape designed to make it more stiff and rigid?

Answer 5

They are designed with:

• lips
• ridges
• ribs

Question 6

Materials such as low density polythene (LDLE) and polypropylene are attacked by ultraviolet light and over time may fade and become brittle. This is called UV degradation. To prevent this what do manufacturers do?

Answer 6

They add UV stabilisers which absorb the UV radiation.