13.5 - Polymerisation in Alkenes Flashcards Preview

OCR A Chemistry A Level - Chapter 13 > 13.5 - Polymerisation in Alkenes > Flashcards

Flashcards in 13.5 - Polymerisation in Alkenes Deck (12)
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1

What is addition polymerisation?

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

2

What conditions are used for industrial polymerisation?

High temperature and pressure using catalysts.

3

What are the benefits of polymers?

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

4

Name one drawback with regards to polymer disposal?

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

5

What are the benefits of recycling polymers?

- 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

6

What are the drawbacks of recycling PVC?

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

7

What use can polymers take if they cannot be recycled?

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

8

What is feedstock recycling?

- 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

9

What are bioplastics?

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.

10

How do biodegradable polymers work?

- 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.

11

What are advantages of biodegradable polymers?

- 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.

12

What are photodegradable polymers?

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