MR - Polymers and their Properties

Question 1

State 2 ways of producing polymers

Answer 1

Addition polymerisation

Condensation polymerisation

Question 2

What molecule forms addition polymers and how?

Answer 2

Alkenes

The double bonds in the alkene can “open-up” and join together with other monomers

Question 3

What 3 types of polymers can be produced by condensation polymerisation

Answer 3

Polyesters
Polyamides
Polypeptides

Question 4

Describe 3 general rules for condensation reactions

Answer 4

1) Condensation polymerisation usually involves two different types of monomer
2) Each monomer has at least 2 functional groups. Each functional group reacts with a group on another monomer to form a link, creating polymer chains
3) Each time a link is formed, a water molecule is lost (hence condensation)

Question 5

Name a natural condensation polymer and name the links formed

Answer 5

Proteins

Peptide bonds are formed

Question 6

Name the reactants that form polyamides

Answer 6

Dicarboxylic acids and diamines

Question 7

Name the reactants for the production of Nylon 6,6

Answer 7

1,6-diaminohexane

hexanedioic acid

Question 8

Name the reactants that form polyesters

Answer 8

Dicarboxylic acids and Diols

Question 9

What does PET stand for?

Answer 9

Polyethylene terephthalate

Question 10

Give the systematic name and homologous series for:

OH(CH₂)₂OH

Answer 10

Ethane-1,2-diol

A diol

Question 11

Give the bonding between monomers for an amide link

Answer 11

• NH - CO -

Question 12

Give the bonding between monomers for an ester link

Answer 12

• CO - O -

Question 13

Define green chemistry for polymers

Answer 13

A ‘green’ polymer manufacturing process should be designed to minimise the impact on human health and the environment

Question 14

Give 5 principles that industrial chemists must follow when designing a ‘green’ polymer manufacturing process

Answer 14

1) Use reactant molecules that are as safe and environmentally friendly as possible
2) Use as few other materials (e.g. solvents) as possible. If you use other chemicals, choose ones which won’t harm the environment
3) Renewable raw materials should be used whenever possible
4) Energy use should be kept to a minimum
5) The process should generate no waste products that are hazardous to human health or the environment

Question 15

State 2 ways in which producing polymers uses energy

Answer 15

• Extracting raw materials

- Creating high temperatures or pressures

Question 16

Give 3 ways of getting rid of plastic waste

Answer 16

1) Burying it in a landfill
2) Recycling it
3) Burning it

Question 17

Give 2 negatives for burying plastic waste in a landfill

Answer 17

• It takes a very long time to decompose

- More energy and raw materials are needed to make new plastics

Question 18

Give a positive and negative for recycling plastics

Answer 18

+ve - Lots of plastics are from non-renewable sources (oil). Recycling them means less raw materials are used, and less waste goes to landfills
-ve - Sorting and processing plastic uses a lot of energy

Question 19

Give a positive and negative for burning plastics

Answer 19

+ve - it reduces the amount of waste going to landfills, and produces heat energy which can be used to generate electricity
-ve - it produces lots of carbon dioxide and also some toxic waste gases

Question 20

State what controls the properties of all materials

Answer 20

The structure, and thus the bonding between molecules

Question 21

Define thermoplastics

Answer 21

Polymers that don’t have any covalent bonds or cross-links between chains. Intermolecular forces are the only thing holding polymer chains together

Question 22

Describe the property of the structure of a thermoplastic for it to be:

i) soft and flexible
ii) rigid

Answer 22

i) The chains are able to slide over one another easily

ii) The chains can’t easily slide over one another

Question 23

Increasing what 2 factors of intermolecular bonding will make a thermoplastic more rigid?

Answer 23

Number of intermolecular forces

Strength of intermolecular forces

Question 24

What property of the structure of a polymer chain dictates the number of intermolecular forces between adjacent chains?

Answer 24

The length of the polymer chains (the number of points of contact)

Question 25

Define Tm

Answer 25

Melting point

Question 26

State and explain what happens to thermoplastics at temperatures higher than their Tm

Answer 26

It will soften and melt
The heat energy you are adding disrupts the intermolecular bonds that hold the polymer chains together, meaning the chains start being able to slide over one another - so the plastic can change shape more easily

Question 27

Define Tg

Answer 27

Glass transition temperature

Question 28

State and explain what happens to thermoplastics at temperatures lower than their Tg

Answer 28

If you try to bend it, it will snap or shatter
Cooling a polymer strengthens the intermolecular bonds that hold the chains together, so the plastic becomes rigid. If force is applied, the chains will not slide past eachother

Question 29

State the 2 ways in which polymer chains can be arranged

Answer 29

Crystalline

Amorphous

Question 30

Describe the arrangement of polymer chains in a crystalline arrangement

Answer 30

The arrangement of chains is ordered - they all run in the same direction or fold up neatly and stack together

Question 31

Describe the arrangement of polymer chains in an amorphous arrangement

Answer 31

The arrangement of the chains is random - they all run in different directions

Question 32

State and explain the difference in strength for crystalline and amorphous polymers

Answer 32

Crystalline polymers are stronger than amorphous polymers because the polymer chains in crystalline polymers can neatly pack and get closer together. The intermolecular forces between polymer chains are therefore much greater for crystalline polymers

Question 33

State 3 ways in which you can alter the properties of a polymer

Answer 33

1) Copolymerisation
2) Adding a plasticiser
3) Cold-drawing

Question 34

Describe copolymerisation and give an example

Answer 34

Making a polymer using a mixture of monomer molecules. You end up with a polymer chain that has different properties from a polymer made from any of the monomers alone

Example: Making a styrene-butadiene copolymer which is very tough and hard-wearing but also flexible

Question 35

Describe the use of adding a plasticiser and give an example

Answer 35

Adding a plasticiser makes a polymer more flexible. The plasticiser molecules get between polymer chains and push them apart, reducing the strength of intermolecular forces - so the chains slide around more

Example: making flexible PVC, which lowers the Tg

Question 36

Describe cold-drawing and give an example

Answer 36

Cold-drawing increases the crystallinity of a polymer
Chains of an amorphous polymer are randomly tangled, so don't lie close together and have weak intermolecular forces
By pulling (drawing) the polymer chains out in a straight line, they are forced to straighten out and lie closer together. The intermolecular forces between the chains increases, so the polymer is more crystalline and stronger

Example: making nylon fibres stronger