C1e

Question 1

why are rigid plastics rigid

Answer 1

there are stronger intermolecular forces between the long chains of polymers which take more energy to overcome, meaning they have high melting points and cannot be stretched

Question 2

why can stretchy plastics be stretched easily

Answer 2

there are weak intermolecular forces between the shorter polymer chains which take less energy to overcome, meaning the molecules can slide over one another

Question 3

what are the properties of nylon. give 2

Answer 3

tough
lightweight
keeps water out
keeps UV out

BUT

does not let water vapour through so sweat condenses

Question 4

what is the difference between GORE-TEX and nylon

Answer 4

breathable - lets water vapour (sweat) through so it does not condense inside the coat

Question 5

why is GORE-TEX both waterproof and breathable

Answer 5

• nylon is laminated with a PTFE membrane
• the holes in the membrane are too small for water molecules to pass through but big enough for water vapour to pass through
• however the membrane by itself is too fragile, must be combined with nylon

Question 6

why would chemists develop polymers that biodegrade or dissolve

Answer 6

so that they do not have to be burned or put in landfills which makes them more greenly disposed of