Unit Two: Polymers

Question 1

What determines the property of a plastic?

Answer 1

The bonds between the different molecule chains

Question 2

WEAK FORCES:

Answer 2

Individual tangled chains of polymers, held together by weak intermolecular forces are free to slide over each other

Question 3

THERMOSOFTENING POLYMERS:

Answer 3

Don’t have cross linking between chains
Forces between the chains are really easy to overcome, so it’s easy to melt the plastic
When it cools, the polymer hardens into a new shape
You can melt these plastics and remould them as many times as you like

Question 4

STRONG FORCES:

Answer 4

Some plastics have stronger intermolecular forces between the polymer chains called crosslinks, that hold the chains firmly together

Question 5

THERMOSETTING POLYMERS:

Answer 5

Have crosslinks which hold the chains together in a solid structure
The polymer doesn’t soften when it’s heated
Thermosetting polymers are strong, hard and rigid

Question 6

What affects the properties of a polymer?

Answer 6

The starting materials and the reaction conditions

Question 7

Name the two types of polythene that can be made and the conditions they are made in:

Answer 7

Low density polythene (flexible-used for bags and bottles):
Heat ethene to about 200 degrees under high pressure

High density polythene (rigid-used for water tanks and drainpipes):
Low temperature and pressure with a catalyst