13.5 - Polymerisation in Alkenes

Question 1

What is addition polymerisation?

Answer 1

Alkenes undergo addition polymerisation to produce long saturated alkanes which have high molecular masses.

Question 2

What conditions are used for industrial polymerisation?

Answer 2

High temperature and pressure using catalysts.

Question 3

What are the benefits of polymers?

Answer 3

• Cheap and readily available
• More convenient than glass, metal dustbins, paper bags
• Lack of reactivity - good for storing foods and chemicals safely

Question 4

Name one drawback with regards to polymer disposal?

Answer 4

Lack of reactivity also means that they are difficult to dispose of, they are mostly non-biodegradable

Question 5

What are the benefits of recycling polymers?

Answer 5

• Reduces environmental impact - no need to burn fossil fuels
• Decreases landfill amount
• Discarded polymers must categorised by type (if poylmers are mixed it renders the recycling process useless)
• Polymers are made into flakes, washed and dried to be melted and reconstructed for use again

Question 6

What are the drawbacks of recycling PVC?

Answer 6

Can’t be burnt as the high chlorine content in PVC and the range of additives make it toxic (releases hydrogen chloride a corrosive gas)

• Nowadays solvents are added to PVC to dissolve the polymer, high grade PVC is recovered in precipitation from solvent, solvent is used again

Question 7

What use can polymers take if they cannot be recycled?

Answer 7

Since some polymers are derived from natural gases or petroleum, they have high stored energy value
- They can be incinerated to produce heat > generate steam for turbines to produce electricity

Question 8

What is feedstock recycling?

Answer 8

• Reclaiming monomers, gases or oils from waste polymers.
• Products of FR resemble those from crude oil refineries
• FR can handle unsorted and unwashed polymers
• Products can be used as raw materials for new polymer production

Question 9

What are bioplastics?

Answer 9

Made from plant starch, cellulose, plant oils
- They are a sustainable alternative to oil-based products
Bioplastic use protects our environments and conserves oil stores.

Question 10

How do biodegradable polymers work?

Answer 10

• Decomposed by microorganisms to form water, CO2 and biological compounds
• Biodegradable polymers usually made from starch or cellulose to allow microorganisms to break them down.

Question 11

What are advantages of biodegradable polymers?

Answer 11

• They live no visible or toxic residues
• Supermarket bags or bin liners can be composted with the rubbish
• New products such as compostable plates, cutlery etc. mean there will be less waste plastic.

Question 12

What are photodegradable polymers?

Answer 12

Photodegradable oil-based polymers are used when biodegradable polymers can’t be used.

• They contain bonds that are weakened by the presences of light - they degrade.
• Or light absorbing additives are used to break them down